JPWO2021194828A5 - - Google Patents

Description

Step 1: Hexadecyl(tert-butoxycarbonyl)-L-phenylalaninate To a stirred mixture of (tert-butoxycarbonyl)-L-phenylalanine (10 g, 37.7 mmol) in chloroform (70 mL) was added HATU (21. 50 g, 56.5 mmol), hexadecane-1-ol (9.14 g, 37.7 mmol), TEA (15.76 mL, 113 mmol) and imidazole (7.70 g, 113 mmol) were added at 0°C. The reaction mixture was stirred at room temperature for 16 hours. LCMS showed the reaction was complete. The reaction mixture was quenched with water (100 mL) and extracted with DCM (100 mL x 2). The combined organic phases were washed with brine (30 mL), dried over Na ₂ SO ₄ and concentrated under vacuum. The residue was purified by flash column chromatography (silica gel, 330 g, petroleum ether: EA = 10:1) to give hexadecyl(tert-butoxycarbonyl)-L-phenylalaninate (8.5 g, purity 100%, yield 46.0%) was obtained as a yellow oil . LCMS (ESI) m/z calcd for C ₃₀ H ₅₁ NO ₄ :489; found: 490 (M+H). ¹ H NMR (400 MHz, CDCl3) δ 7.38 - 7.12 (m, 5H), 5.00 (d, J = 11.2 Hz, 1H), 4.65 - 4.52 (m, 1H), 4.10(t, J = 8.8 Hz, 2H), 3.18 - 2.98(m, 2H), 1.71 - 1.52 (m, 4H), 1.50 - 1.19 (m, 33H), 0.97 - 0.83 (m, 3H).

Step 2: Docosyl-L-phenylalaninate A solution of dodecyl (tert-butoxycarbonyl)-L-phenylalaninate (6.3 g, 14.53 mmol) in DCM (60 mL) stirred at 25 °C in air. TFA (20 mL, 260 mmol) was added. The reaction mixture was stirred at 25°C for 30 minutes. LCMS showed the reaction was complete. The reaction was quenched with saturated aqueous _NaHCO3 , pH was adjusted to 8, and the organic layer was separated. The aqueous phase was extracted with DCM (30 mL x 3). The combined organic layers were washed with brine, dried over anhydrous sodium sulfate, and concentrated to dryness under vacuum to give the title compound (5 g, 79%, 82% yield) as a red oil. LCMS (ESI) m/z calcd for C ₂₁ H ₃₅ NO ₂ : 333; found: 334 (M+1). ¹ H NMR (400 MHz, Chloroform-d) δ 7.69 (s, 2H), 7.30 - 7.26 ( m, 3H), 7.23 - 7.14 (m, 2H), 4.17 (t, J = 6.8 Hz, 1H), 4.04 (t, J = 6.8 Hz, 2H), 3.29 - 3.15 (m, 2H), 1.54 - 1.46 (m, 2H), 1.33 - 1.25 (m, 18H), 0.88 (t, J = 6.8 Hz, 3H).

Step 4: Dodecyl (((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl) -3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate stirred at 25°C under nitrogen ((2R,3S,5R) -2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran To a solution of pyridine (10 mL)/THF (10 mL) of methanol (2.309 g, 2.76 mmol) was added dropwise a solution of 1M tert-butylmagnesium chloride/THF (3.86 mL, 3.86 mmol). Then, a solution of dodecyl( chloro (phenoxy)phosphoryl)-L-phenylalaninate (1.4 g, 2.76 mmol) in THF (5 mL) was added dropwise to the resulting reaction mixture. The reaction mixture was stirred at 25°C for 1.5 hours. LCMS showed the reaction was complete. The reaction was concentrated to dryness in vacuo. The crude product was subjected to reverse phase HPLC purification (C18, 25-100% MeCN/water with 0.1% _{HN HCO} ) to give the title compound (1.6 g, 99%, yield: 43.9% ) was obtained as a yellow oil. LCMS (ESI) m/z calcd for C ₇₉ H ₈₂ FN ₆ O ₉ P: 1309; found: 1310 (M+1). ¹ H NMR (400 MHz, Chloroform-d) δ 7.72 - 7.26 (m, 12H) , 7.26 - 6.90 (m, 21H), 6.83 - 6.70 (m, 4H), 6.15 - 6.11 (m, 1H), 4.51 (q, J = 6.4 Hz, 1H), 4.29 - 4.17 (m, 1H), 4.09 - 4.05 (m, 2H), 3.94 - 3.92 (m, 2H), 3.85 - 3.83 (m, 1H), 3.77 (s, 3H), 3.72 (s, 3H), 3.30 (t, J = 10.4 Hz, 1H ), 2.99 - 2.77 (m, 3H), 1.94 - 1.92 (m, 1H), 1.84 - 1.72 (m, 1H), 1.65 (d, J = 7.2 Hz, 2H), 1.46 (d, J = 7.6 Hz, 2H), 1.27 - 1.22 (m, 18H), 0.88 (t, J = 6.8 Hz, 3H).

Step 3: Decyl(((S)-1-(decyloxy)-1-oxopropan-2-yl)oxy)((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6 -(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenyl)methoxy)tetrahydrofuran-2-yl)methoxy)phosphoryl)-L- Phenylalaninate ((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H- stirred at room temperature under nitrogen) To a solution of purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methanol (1.0 g, 1.193 mmol) in THF (12 mL) was added tert-butylmagnesium chloride/THF. (1.790 mL, 1.790 mmol) solution was added and stirred at 25° C. for 1 hour. Then, decyl((((S)-1-(decyloxy)-1-oxopropan-2-yl)oxy)(4-nitrophenoxy)phosphoryl)-L-phenylalaninate (1.716 g, 2.387 mmol) was added to the reaction at 25°C. The resulting mixture was stirred at room temperature for 6 hours. LCMS showed the reaction was complete. The reaction mixture was concentrated and the residue was purified by silica gel column (120 g, petroleum ether:EtOAc=1:1) to give decyl (((S)-1-(decyloxy)-1-oxopropan-2-yl). )oxy)(((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3 -((4-methoxyphenyl)diphenyl)methoxy)tetrahydrofuran-2-yl)methoxy)phosphoryl)-L-phenylalaninate (650 mg, 0.458 mmol, yield 38.4%) was obtained as a yellow solid. LCMS (ESI) m/z calcd for C ₈₄ H ₉₈ FN ₆ O ₁₁ P: 1417; found: 1418 (M+1).

Step 4: Decyl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy) (((S)-1-(decyloxy)-1-oxopropan-2-yl)oxy)phosphoryl)-L-phenylalaninatedecyl (((S)-1-(decyloxy)-1-oxopropane- 2-yl)oxy)(((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl )-3-((4-methoxyphenyl) diphenylmethoxy )tetrahydrofuran-2-yl)methoxy)phosphoryl)-L-phenylalaninate (650 mg, 0.298 mmol) in DCM (6 mL) was added with TFA (0. 600 mL) was added at 0°C and stirred at room temperature for 2 hours. LCMS showed the reaction was complete. The pH was adjusted to 6-7 with saturated aqueous NaHCO ₃ and extracted with DCM (3×10 mL). The combined organic layers were washed with brine and dried _{over Na2SO4} . After filtration, the filtrate was concentrated, and the residue was purified with a silica gel column (80 g, MeOH:DCM=1:19) to obtain decyl (((2R,3S,5R)-5-(6-amino-2-fluoro -9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(((S)-1-(decyloxy)-1-oxopropan-2-yl)oxy)phosphoryl) -L-phenylalaninate (250 mg) was obtained as a yellow oil. The isomers were separated under the following conditions (Column: DAICEL Dcpak P4VP, 4.6 x 50 mm, 3 μm; Mobile phase A:, Mobile phase B: ACN:MeOH = 80:20 (20 mM NH ₃ ); Flow rate: 2 mL/min; Gradient : 5% B; 220 nm; RT1: 2.68; RT2: 2.87) and the fraction containing the desired compound was concentrated to obtain two isomers. The first eluting isomer (Example 10A, RT 1:2.68) was recrystallized from ACN/ _H2O in a 1:1 ratio. The solid was collected by filtration and dried in a sun lamp (45° C.) to give 60 mg (0.066 mmol, 22.07% yield) as a white crystalline solid. LCMS (ESI) m/z calcd for C ₄₄ H ₆₆ FN ₆ O ₉ P: 872; found: 873(m+1). ¹ H NMR (300 MHz CDCl ₃ ).δ 8.12 (s, 1H), 7.26 - 7.16 (m, 5H), 6.36 (s, 1H), 6.28 - 5.82 (m, 1H), 4.74 (t, J = 6 Hz, 2H), 4.35 - 4.06 (m, 7H), 3.85 (s, 1H) , 3.58 (s, 1H), 3.07 - 2.98 (m, 2H), 2.72 (s, 3H),1.64 - 1.56 (m, 4H), 1.38 (d, J = 3 Hz, 4H), 1.25 (s, 27H) ), 0.88 (t, J = 6 Hz, 6H). The second eluting isomer (Example 10B, RT2: 2.87) was recrystallized from ACN/ _H2O . The solid was collected by filtration and dried under a sun lamp (45° C.) to yield 48 mg (0.051 mmol, 17.28% yield) as a white amorphous solid. LCMS (ESI) m/z calcd for C ₄₄ H ₆₆ FN ₆ O ₉ P: 872; found: 873(m+1). ¹ H NMR (300 MHz CDCl ₃ ).δ 8.09 (s, 1H), 7.26 ( s, 3H), 7.23 - 7.14 (m, 2H), 6.35 (t, J = 6 Hz, 1H), 6.09 (s, 1H), 4.80 (s, 1H), 4.56 (t, J = 9 Hz, 1H ), 4.31 - 4.08 (m, 7H), 3.81 (s, 1H), 3.55 - 3.47 (m, 1H), 3.16 (t, J = 3 Hz, 1H), 3.00 - 2.93 (m, 1H), 1.74 ( t, J = 3 Hz, 3H), 2.03 (s, 1H),1.73-1.55 (m, 5H),1.49 (d, J = 3 Hz, 3H), 1.26 (br s, 27H), 0.88 (t, J = 6 Hz, 6H).

Step 5: Dodecyl ((2-(dodecyloxy)-2-oxoethoxy)(((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenyl) methyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)phosphoryl)-L-phenylalaninate ((2R,3S,5R) -2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran Tert-butylmagnesium chloride/THF (1.253 mL x 2, 1.253 mmol) was added to a mixture of methanol (700 mg x 2, 0.835 mmol) in tetrahydrofuran (7 mL) under a nitrogen atmosphere at 0°C. added. The reaction mixture was stirred at room temperature for 1 hour. Dodecyl((2-(dodecyloxy)-2-oxoethoxy)(4-nitrophenoxy)phosphoryl)-L-phenylalaninate (1271 mg×2, 1.671 mmol) was added to the reaction mixture at 0°C. The reaction mixture was stirred at room temperature for 12 hours. LCMS showed the reaction was complete. The reaction mixture was purified by a gel silica column (120 g, petroleum ether:EtOAc=5:1) and purified with dodecyl ((2-(dodecyloxy)-2-oxoethoxy)(((2R,3S,5R)-2-ethynyl -5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy )tetrahydrofuran- 2-yl)methoxy)phosphoryl)-L-phenylalaninate (2 g, 1.233 mmol, yield 73.8%) was obtained as a yellow solid. LCMS (ESI) m/z calcd for C ₈₇ H ₁₀₄ FN ₆ O ₁₁ P: 1459; found: 1460 (M+H).

Step 6: Dodecyl((((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(2-(dodecyloxy)-2-oxoethoxy)phosphoryl)-L-phenylalaninate To a solution of dodecyl((2-(dodecyloxy)-2-oxoethoxy)(((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl )diphenylmethoxy)tetrahydrofuran -2-yl)methoxy)phosphoryl)-L-phenylalaninate (2 g, 1370 mmol) in DCM (20 mL) stirred at room temperature was added TFA (2 mL, 26.0 mmol) dropwise. The reaction mixture was stirred at room temperature for 1 h. LCMS showed the reaction was complete. The reaction mixture was quenched with water and extracted with dichloromethane (20 mL). The organic phase was washed with saturated _NaHCO3 solution (20 mL) and saturated brine (20 mL), dried over sodium sulfate, and evaporated under vacuum to give the crude product as a yellow oil. The crude product was purified by silica gel column (120 g, DCM:MeOH=10:1) to give the title compound (1 g) as a yellow oil. The isomers were separated by SCF (column: CHIRALPAK AS-H, 2.0×25 cm L (5 μm); mobile phase A: CO ₂ , mobile phase B: IPA; flow rate: 80 mL/min; gradient: 50% B; 220 nm; RT1: 3.01; RT2: 4.45; injection volume: 2 mL; number of runs: 11) to give the first eluting isomer (Example 11A, 309.5 mg, RT: 3.01) as a white solid: LCMS (ESI) m/z calcd for C ₄₇ H ₇₂ FN ₆ O ₉ P: 914; found: 915 (M+H). ¹ H NMR (400 MHz, Chloroform-d) δ 8.17 (s, 1H), 7.32 - 7.14 (m, 5H), 6.38 - 6.31 (m, 1H), 6.13 (s, 2H), 4.86 (t, J = 8.0 Hz, 1H), 4.39 (dd, J = 16.4, 10.0 Hz, 1H), 4.31 - 3.98 (m, 9H), 3.55 - 3.44 (m, 1H), 3.19 - 3.10 (m, 1H), 2.93 (dd, J = 13.6, 8.0 Hz, 1H), 2.79 - 2.70 (m, 3H), 1.66 - 1.56 (m, 4H), 1.34 - 1.22 (m, 36H), 0.92 - 0.84 (m, 6H), and the second eluting isomer (Example 11B, 265.9 mg, RT: 4.45) was obtained as a white solid: LCMS (ESI) m/z calcd for C47H72FN6O9P: 914; found: 915 (M+H). ^1H NMR (400 MHz, Chloroform-d) δ 8.07 (s, 1H), 7.29 - 7.14 (m, 5H), 6.39 - 6.11 (m, 3H), 4.71 (t, J = 7.6 Hz, 1H), 4.41 (dd, J = 16.0, 10.4 Hz, 1H), 4.26 - 4.04 (m, 8H), 3.83 - 3.73 (m, 2H), 3.16 - 3.06 (m, 1H), 2.93 (dd, J = 14.0, 8.0 Hz, 1H), 2.75 - 2.62 (m, 3H), 1.68 - 1.53 (m, 4H), 1.34 - 1.22 (m, 36H), 0.92 - 0.84 (m, 6H).

Step 3: Decyl (((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl) -3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninatedecyl L-alaninate (3 g, 13.08 mmol), TEA (1.823 mL, 13. A solution of phenylphosphorodichloridate (2.76 g, 13.08 mmol) in DCM (30 mL) is stirred at room temperature under nitrogen for 1 h. Then , ( (2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-( (4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methanol (1.5 g, 1.790 mmol) and 1M tert-butylmagnesium chloride/THF (18.31 mL, 18.31 mmol) in THF (15 mL)/pyridine. (15.0 mL) The solution was stirred at room temperature for 30 minutes and added to the above mixture. The reaction mixture was stirred at room temperature overnight. LCMS showed the reaction was complete. The reaction mixture was quenched with water and partitioned between dichloromethane (100 mL) and water (100 mL). The organic phase was washed with water (100 mL) and saturated brine (100 mL), dried over sodium sulfate, and evaporated under vacuum to give the crude product as a white solid. The residue was purified by gel silica column (330 g, petroleum ether:EtOAc=1:1) to give decyl (((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(( (4-methoxyphenyl)diphenylmethyl )amino )-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L- Alaninate (1 g, purity 93.9%, yield 5.96%) was obtained as a white solid. LCMS (ESI) m/z calcd for C ₇₁ H ₇₄ FN ₆ O ₉ P: 1204; found: 1205. ¹ H NMR (300 MHz, Chloroform-d) δ 7.80 - 7.68 (m, 1H), 7.62 - 7.51 ( m, 4H), 7.47 - 7.02 (m, 25H), 6.92 - 6.73 (m, 4H), 6.25 - 6.06 (m, 1H), 4.65 - 4.53 (m, 1H), 4.38 - 4.28 (m, 2H), 4.20 - 4.02 (m, 4H), 3.82 - 3.72 (m, 6H), 3.57 - 3.46 (m, 1H), 2.89 - 2.83 (m, 1H), 2.04 - 1.94 (m, 1H), 1.92 - 1.84 (m , 1H), 1.78 - 1.69 (m, 2H), 1.51 - 1.41 (m, 2H), 1.32 - 1.24 (m, 15H), 0.90 (t, J = 6.0 Hz, 3H).

Step 4: Decyl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy) (phenoxy)phosphoryl)-L-alaninate Decyl(((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenyl) stirred under nitrogen methyl )amino )-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L- alaninate ( 1 g, 0. To a solution of 830 mmol) in DCM (10 mL) at room temperature was added TFA (1 mL, 12.98 mmol). The reaction mixture was stirred at room temperature for 1 hour. LCMS showed the reaction was complete. The reaction mixture was quenched with water and extracted with DCM (20 mL). The organic phase was washed with saturated sodium carbonate (25 mL), water (25 mL) and saturated brine (25 mL), dried over sodium sulfate and evaporated under vacuum to give the crude product as a white solid. The crude product was subjected to preparative SFC (column: CHIRALPAK IA, 2 x 25 cm, 5 μm; mobile phase A: Hex: DCM = 3:1 (0.1% FA)-HPLC, mobile phase B: EtOH-HPLC; flow rate: 15 mL/min; Gradient: 30B to 30B in 10 minutes; 220/254 nm; RT1: 5.582; RT2: 7.933; Injection volume: 1 mL; Number of runs: 6) and the first eluting isomer (Example 13A, RT1: 5.582, 100 mg) was obtained as a white solid (this solid was prepared using an achiral column (DAICEL DCpak P4VP, 20 x 250 cm, 5 μm; mobile phase A: CO ₂ , mobile phase B: MeOH (8 mmol)). /L NH ₃ /MeOH)-HPLC; flow rate: 50 mL/min; gradient: 20% B; 254 nm; injection volume: 1.5 mL; number of runs: 4) to repurify the first eluting isomer (run Example 13A, RT1: 6.63, 60.8 mg) was obtained as a white solid.): LCMS (ESI) m/z calcd for C ₃₁ H ₄₂ FN ₆ O ₇ P: 660; found: 661(M+H ). ¹ H NMR (400 MHz, DMSO-d6) δ 8.25 (s, 1H), 7.85 (s, 2H), 7.35 - 7.26 (m, 2H), 7.18 - 7.09 (m, 3H), 6.28 (dd, J = 7.6, 4.8 Hz, 1H), 6.02 - 6.00 (m, 1H), 5.83 (d, J = 5.2 Hz, 1H), 4.66 - 4.64 (m, 1H), 4.21 (dd, J = 10.8, 5.6 Hz , 1H), 4.10 (dd, J = 11.2, 4.4 Hz, 1H), 3.98 - 3.89 (m, 2H), 3.72 - 3.64 (m, 2H), 2.83 - 2.74 (m, 1H), 1.49 - 1.44 (m , 2H), 1.28 - 1.08 (m, 17H), 0.89 - 0.81 (m, 3H), the second eluting isomer (Example 13B, RT: 7.933, 104.9 mg) was obtained as a white solid. :LCMS (ESI) m/z calcd for C ₃₁ H ₄₂ FN ₆ O ₇ P: 660; found: 661(M+H). ¹ H NMR (300 MHz, DMSO-d6) δ 8.27 (s, 1H), 7.85 (s, 2H), 7.38 - 7.26 (m, 2H), 7.22 - 7.08 (m, 3H), 6.28-6.24 (m, 1H), 6.03 - 6.00 (m, 1H), 5.86 - 5.73 (m, 1H) ), 4.66 - 4.56 (m, 1H), 4.24 (dd, J = 10.5, 5.7 Hz, 1H), 4.06 (dd, J = 11.1, 4.8 Hz, 1H), 3.99 - 3.71 (m, 3H), 3.64 ( s, 1H), 2.83 - 2.67 (m, 1H), 1.53 - 1.37 (m, 2H), 1.31 - 1.11 (m, 17H), 0.89 - 0.80 (m, 3H).

Step 3: Decyl (((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl) -3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate Dodecyl L-alaninate (3 g, 11.65 mmol), TEA (4.87 mL, 35. A solution of phenylphosphorodichloridate (2.459 g, 11.65 mmol) in DCM (30 mL) was stirred at room temperature under nitrogen for 1 h. Then, ((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-( (4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methanol (1.5 g, 1.790 mmol) and tert-butylmagnesium chloride/THF (16.32 mL, 16.32 mmol) in THF (15 mL)/pyridine ( 15 mL) solution was stirred at room temperature for 30 minutes and added to the above mixture. The resulting reaction mixture was stirred at room temperature overnight. The reaction mixture was quenched with water and partitioned between dichloromethane (100 mL) and water (100 mL). The organic phase was washed with water (100 mL) and saturated brine (100 mL), dried over sodium sulfate, and evaporated under vacuum to give the crude product as a white solid. The residue was purified by gel silica column (330 g, petroleum ether:EtOAc=1:1) to give dodecyl (((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(( (4-methoxyphenyl)diphenylmethyl )amino )-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L- Alaninate (1.8 g, 98% purity, 12.27% yield) was obtained as a white solid. LCMS (ESI) m/z calcd for C ₇₃ H ₇₈ FN ₆ O ₉ P: 1233; found:1234 (M+1). ¹ H NMR (300 MHz, Chloroform-d) δ 7.79 - 7.71 (m, 1H) , 7.60 - 7.49 (m, 4H), 7.45 - 7.04 (m, 25H), 6.90 - 6.74 (m, 4H), 6.21 - 6.13 (m, 1H), 4.65 - 4.53 (m, 1H), 4.33 (t, J = 6.6 Hz, 2H), 4.26 - 4.17 (m, 1H), 4.15 - 4.00 (m, 3H), 3.84 - 3.71 (m, 6H), 3.59 - 3.42 (m, 1H), 2.05 - 1.97 (m, 1H), 1.75 (dd, J = 8.7, 6.3 Hz, 2H), 1.54 - 1.41 (m, 2H), 1.27 (br s, 19H), 0.93 - 0.86 (m, 3H).

Step 4: Dodecyl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy) (phenoxy)phosphoryl)-L-alaninate Dodecyl (((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)) is stirred at room temperature under nitrogen. ) diphenylmethyl )amino )-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate (1.8g , 1.459 mmol) in DCM (18 mL) was added TFA (1.8 mL, 23.36 mmol). The reaction mixture was stirred at room temperature for 1 hour. LCMS showed the reaction was complete. The reaction mixture was quenched with water and extracted with dichloromethane (20 mL). The organic phase was washed with saturated sodium bicarbonate solution (20 mL), water (25 mL) and saturated brine (25 mL), dried over sodium sulfate and evaporated under vacuum to give the crude product as a white solid. The crude product was subjected to preparative SFC (column: CHIRALPAK IH, 2 x 25 cm, 5 μm; mobile phase A: CO ₂ , mobile phase B: MEOH (2mM NH ₃ -MEOH); flow rate: 5 mL/min; gradient: 30% B ; 220 nm; RT1: 3.94; RT2: 5.13; Injection volume: 1.5 mL; Number of runs: 14) to obtain the first eluting isomer (Example 14A, RT: 3.94, 300 mg ) was obtained as a white solid, which was purified using a preparative achiral column (column: DAICEL DCpak P4VP, 20 x 250 cm, 5 μm; mobile phase A: CO ₂ , mobile phase B: MeOH (8 mmol/L NH ₃ .MeOH)-HPLC; Flow rate: 50 mL/min; gradient: 25% B; 254 nm; injection volume: 1 mL; number of runs: 10) to further purify the first eluting isomer (Example 14A, RT1: 3.85, 178.3 mg ) obtained: LCMS (ESI) m/z calcd for C ₃₃ H ₄₆ FN ₆ O ₇ P: 688; found: 689 (M+H). ¹ H NMR (400 MHz, DMSO-d6) δ 8.27 (s, 1H), 7.86 (br s, 2H), 7.32 (d, J = 7.6 Hz, 2H), 7.20 - 7.11 (m, 3H), 6.30 - 6.23 (m, 1H), 6.06 - 5.95 (m, 1H), 5.79 (d, J = 5.6 Hz, 1H), 4.66 - 4.57 (m, 1H), 4.28 - 4.20 (m, 1H), 4.10 - 4.02 (m, 1H), 3.99 - 3.90 (m, 1H), 3.89 - 3.74 (m, 2H), 3.65 (s, 1H), 3.34 (s, 2H), 2.79 - 2.71 (m, 1H), 1.49 - 1.39 (m, 2H), 1.28 - 1.15 (m, 19H), 0.89 - 0.81 (m, 3H), the second eluting isomer (Example 14B, RT: 5.13, 200 mg) was obtained as a white solid, which was applied to a preparative chiral column (column: CHIRALPAK IA, 2 x 25 cm, 5 μm; Mobile phase A: Hex:DCM=3:1 (0.1% FA)-HPLC, mobile phase B: IPA-HPLC; flow rate: 20 mL/min; gradient: 30B to 30B in 8 minutes; 220/254 nm; RT1: Further purification by 4.103; RT2: 6.726; injection volume: 1 mL; number of runs: 4) yielded 99.0 mg of product (RT: 4.103): LCMS (ESI) m/z calcd for C ₃₃ H ₄₆ FN ₆ O ₇ P: 688; found: 689 (M+H). ¹ H NMR (400 MHz, DMSO-d6) δ 8.25 (s, 1H), 7.88 (brs, 2H),7.35 - 7.26 (m, 2H), 7.18 - 7.09 (m, 3H), 6.32 - 6.24 (m, 1H), 6.05 - 5.94 (m, 1H), 5.82 (d, J = 5.6 Hz, 1H), 4.64 (t , J = 6.4 Hz, 1H), 4.26 - 4.17 (m, 1H), 4.14 - 4.06 (m, 1H), 3.94 (t, J = 5.6 Hz, 2H), 3.75 - 3.62 (m, 2H), 2.84 - 2.71 (m, 1H), 1.49 - 1.43 (m, 2H), 1.28 - 1.14 (m, 21H), 0.89 - 0.81 (m, 3H).

Step 3: Hexadecyl (((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl) -3-((4-Methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate Hexadecyl L-alaninate (2 g, 6.38 mmol) being stirred at 0° C. under nitrogen. ) and TEA (1.937 g, 19.14 mmol) in DCM (20 mL) was added phenylphosphorodichloridate (1.615 g, 7.65 mmol) in portions. The reaction mixture was stirred at room temperature for 1 hour.
((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purine-9 is stirred at room temperature under nitrogen. -yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methanol (2.67 g, 3.19 mmol) in pyridine (10.0 mL)/THF (10.0 mL), tert -Butylmagnesium chloride/THF (8.93 mL, 8.93 mmol) solution was added dropwise. The reaction mixture was stirred at 25°C for 0.5 hour. The above solution was then added to the reaction mixture at room temperature. The resulting mixture was stirred at 25°C for 16 hours. LCMS showed the reaction was complete. The reaction mixture was evaporated in vacuo to give the crude product as a red oil. This oil was purified by a silica column (120 g) using a 0% to 60% EtOAc/petroleum ether solvent gradient to give hexadecyl (((2R,3S,5R)-2-ethynyl-5-(2- Fluoro-6-(((4-methoxyphenyl)diphenylmethyl )amino )-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy ) Phosphoryl)-L-alaninate (800 mg, purity 80%, yield 7.78%) was obtained as a pale yellow semi-solid. LCMS (ESI) m/z calcd for C ₈₃ H ₉₈ FN ₆ O ₉ P: 1288; found: 1289 (M+1).

Step 3: Docosyl((((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate To a solution of docosyl L-alaninate (2 g, 5.03 mmol) and TEA (1.527 g, 17.09 mmol) in DCM (20 mL) stirred under nitrogen at 0° C. was added phenyl phosphorodichloridate (1.273 g, 6.03 mmol) in portions. The reaction mixture was stirred at room temperature for 1 h.
To a solution of ((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl)amino)-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methanol (2.107 g, 2.51 mmol) in pyridine (10.0 mL)/THF (10.0 mL) stirred at room temperature under nitrogen was added tert-butylmagnesium chloride/THF (7.04 mL, 7.04 mmol) in portions. The reaction mixture was stirred at 25° C. for 0.5 h. To this reaction mixture was then added the above solution at room temperature. The resulting mixture was stirred at 25° C. for 16 h. LCMS and TLC showed the reaction was complete. The reaction mixture was evaporated in vacuo to give the crude product as a red oil. The oil was purified by silica column (120 g) using a 0% to 60% EtOAc/petroleum ether solvent gradient to give docosyl((((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl )amino )-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate (1.8 g, 80% purity, 20.84% yield) as a pale yellow semi-solid. LCMS (ESI) m/z calcd _{for C83H98FN6O9P} : 1372; found: 1373 ( _M + ₁ ). ^1H NMR (400 MHz, Chloroform-d) δ 7.94 (s, 1H), 7.59 - 7.45 (m, 4H), 7.37 - 7.00 (m, 26H), 6.85 - 6.73 (m, 4H), 6.15 - 6.10 (m, 1H), 4.51 - 3.94 (m, 4H), 3.84 - 3.66 (m, 10H), 2.89 - 2.64 (m, 2H), 2.07 - 1.91 (m, 2H), 1.42 - 1.17 (m, 41H), 0.90 - 0.84 (m, 3H).

Step 4: Docosyl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy) (phenoxy)phosphoryl)-L-alaninate Docosyl(((2R,3S,5R)-2-ethynyl-5-(2-fluoro-6-(((4-methoxyphenyl)diphenylmethyl) stirred at room temperature )-amino )-9H-purin-9-yl)-3-((4-methoxyphenyl)diphenylmethoxy)tetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate (2.1 g, 1. To a solution of 529 mol) in DCM (15 mL) was added TFA (2 mL, 26.0 mmol) dropwise and stirred for 30 minutes. LCMS showed the reaction was complete. The reaction mixture was quenched with NaHCO ₃ (100 mL) and extracted with DCM (60 mL x 2). The organic phases were combined, washed with brine (15 mL), dried over Na ₂ SO ₄ and concentrated under vacuum. The residue was purified by silica gel column (120 g, petroleum ether:EtOAc=1:1) to give the desired product as a colorless semi-solid. The isomers were separated by preparative SFC under the following conditions (column: CHIRALPAK IG, 3 x 25 cm, 5 μm; mobile phase A: CO ₂ , mobile phase B: IPA; flow rate: 80 mL/min; gradient: 50% B; 220 nm; RT1: 6.41; RT2: 18.31; Injection volume: 4.5 mL; Number of runs: 5). The first eluting isomer, Example 16A (RT1: 6.41), was collected to yield 329.7 mg (97.6% purity, 25.5% yield) as a white solid. ¹ H NMR (400 MHz, Chloroform-d) δ 8.03 (s, 1H), 7.36 - 7.10 (m, 5H), 6.63 - 6.01 (m, 3H), 4.71 (t, J = 7.6 Hz, 1H), 4.44 - 4.34 (m, 2H), 4.13 - 3.97 (m, 3H), 3.81 (t, J = 10.4 Hz, 1H), 2.77 (s, 1H), 2.76 - 2.62 (m, 2H), 1.63 - 1.54 (m , 2H), 1.39 - 1.17 (m, 41H), 0.90 - 0.84 (m, 3H).The second isomer, Example 16B (RT2: 18.31), was recovered to yield 188.1 mg (purity 98 .06%, yield 14.5%) was obtained as a white solid. LCMS (ESI) m/z calcd for C ₄₃ H ₆₆ FN ₆ O ₇ P: 828; found: 829 (M+1). ¹ H NMR (400 MHz, Chloroform-d)δ 8.05 (s, 1H), 7.34 - 7.12 (m, 5H), 6.33 (dd, J = 4.0, 7.2 Hz, 1H), 6.15 - 5.76 (m, 2H), 4.85 (t, J = 6.4 Hz, 1H), 4.43 - 4.28 (m, 2H) ), 4.18 - 3.97 (m, 3H), 3.77 (t, J = 10.4 Hz, 1H), 3.52 (br, s, 1H), 2.84 - 2.67 (m, 3H), 1.63 - 1.54 (m, 2H), 1.39 (d, J = 6.8 Hz, 3H), 1.34 - 1.17 (m, 38H), 0.90 - 0.84 (m, 3H).

Step 1: Tetradecyl(tert-butoxycarbonyl)-L-phenylalaninate (tert-butoxycarbonyl)-L-phenylalanine (15 g, 56.5 mmol), 2-(3H-[1,2,3]triazolo[4, 5-b]pyridin-3-yl)-1,1,3,3-tetramethylisouronium hexafluorophosphate (V) (32.2 g, 85 mmol) and tetradecane-1-ol (14.55 g, 67. 8 mmol) in DCM (200 mL) were added 1H-imidazole (11.55 g, 170 mmol) and N-ethyl-N-isopropylpropan-2-amine (21.92 g, 170 mmol). The resulting mixture was stirred at 25°C overnight. TLC showed the reaction was complete. The reaction was diluted with water (200 mL) and DCM (100 mL). The organic layer was separated and the aqueous layer was extracted with DCM (2 x 200 mL). The combined organic layers were then washed with brine (200 mL), dried over Na ₂ SO ₄ , filtered, and concentrated to give the crude product. The residue was purified by combiflash (silica gel column 330 g, hexane:ethyl acetate=20:1). The appropriate fractions containing the desired product were combined and the solvent was removed in vacuo to yield tetradecyl(tert-butoxycarbonyl)-L-phenylalaninate (20 g, 41.2 mmol, 72.8% yield). Obtained as a yellow solid. LCMS (M+Na) = 485.0; retention time (0.1% TFA) = 3.56 minutes.

Step 1: Octadecyl(tert-butoxycarbonyl)phenylalaninate octadecane -1-ol (32.5g, 120mmol), (tert-butoxycarbonyl)-L-phenylalanine (29g, 109mmol) and HATU (62.3g, 164mmol) To a solution of DCM (100 mL) was added 1H-imidazole (22.32 g, 328 mmol) and DIPEA (57.3 mL, 328 mmol). The resulting mixture was stirred at 25°C overnight. TLC (petroleum ether:EtOAc=10:1, Rf=0.5) showed completion of the reaction. The reaction was quenched with water (200 mL) and DCM (100 mL). The organic layer was then separated and the aqueous layer was extracted with DCM (2 x 50 mL). The combined organic layers were washed with brine (200 mL), dried over Na ₂ SO ₄ , filtered, and concentrated to give the crude product. The residue was purified by combiflash (silica gel column 330 g, hexane:ethyl acetate=20:1). Appropriate fractions containing the desired product were combined and concentrated in vacuo to give octadecyl(tert-butoxycarbonyl)phenylalaninate (32 g, 61.8 mmol, 56.5% yield) as a yellow solid. .

Step 3: Heptadecan-9-yl(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2- yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate heptadecan- 9-yl L-phenylalaninate (2.75 g, 6.82 mmol), triethylamine (0.951 mL, 6.82 mmol) in DCM (60 mL) To the solution was added a solution of phenylphosphorodichloridate (1.019 mL, 6.82 mmol) in DCM (1 mL) under nitrogen atmosphere at about 5° C., and then the reaction mixture was stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (1 g, 3.41 mmol) To a THF (20 mL)/pyridine (10 mL) solution of tert-butylmagnesium chloride (8.52 mL, 8.52 mmol) was added dropwise at about 5° C. under a nitrogen atmosphere, and the mixture was then stirred at room temperature for 30 minutes. The first prepared mixture was slowly added to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. The mixture was filtered and concentrated to give a yellow solid. The solid was then dissolved in EtOAc (40 mL) and partitioned with HCl (0.05N, 20 mL). The layers were separated and the aqueous layer was extracted with EtOAc (30 x 2 mL). The combined organic layers were washed with brine, dried over Na ₂ SO ₄ , filtered, and concentrated to give the crude product. The residue was purified by reverse phase chromatography (SepaFlash® C18, 0-100% CH ₃ CN/10 mM NH ₄ HCO ₃ H ₂ O) to give heptadecan-9-yl ((((2R,3S, 5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate ( 600 mg, 0.660 mmol, yield 19.36%) was obtained as a pale yellow solid. LCMS (M+H) = 835.4; retention time (0.1% TFA) = 2.474 and 2.506 minutes. Diastereomers were separated by preparative SFC (equipment: SFC-150 (Waters), column: OX 20 x 250 mm, 10 μm (Daicel), column temperature: 35°C; mobile phase: CO ₂ /EtOH (0.5% ammonia / methanol). )=65/35; flow rate: 100 g/min, back pressure: 100 bar; detection wavelength: 214 nm, cycle time: 5 minutes, sample solution: 700 mg dissolved in 60 mL methanol, injection volume: 3 mL). , the first eluting isomer (Example 23A, RT1: 1.13 min, 109 mg, 0.125 mmol, yield 17.43%) was obtained; LCMS (M+H) = 835.4; retention time (0.1 % TFA) = 2.468 min; HPLC: Retention time (0.1% _NH4HCO3 ) = 9.409 min; ^1H NMR (400 MHz, _CDCl3 ) δ 7.92 ₍ s, 1H), 7.25-7.17 (m, 5H), 7.14 (d, J = 7.3 Hz, 1H), 7.12-7.08 (m, 4H), 6.31 (dd, J = 7.3, 4.3 Hz, 1H), 6.10 (s, 2H), 4.71 ( t, J = 7.6 Hz, 1H), 4.26 (dd, J = 11.2, 7.7 Hz, 2H), 4.20 (dd, J = 11.3, 8.8 Hz, 1H), 4.03 (t, J = 6.7 Hz, 2H), 3.88 (s, 1H), 2.99 (d, J = 6.2 Hz, 2H), 2.76-2.63 (m, 3H), 1.86 (s, 2H), 1.24 (d, J = 9.0 Hz, 30H), 0.88 (t , J = 6.8 Hz, 3H), the second eluting isomer (Example 23B, RT2: 2.12 min, 145 mg, 0.167 mmol, 23.29% yield) as a white solid; LCMS (M+H) = 835.3; Retention time (0.1% TFA) = 2.505 minutes; HPLC: Retention time (0.1% NH ₄ HCO ₃ ) = 9.584 minutes; ¹ H NMR (400 MHz, CDCl ₃ ) δ7.78 (s, 1H), 7.30-7.26 (m, 2H), 7.23 (dd, J = 8.4, 4.6 Hz, 3H), 7.15 (d, J = 7.8 Hz, 3H), 7.06 (dd, J = 7.5, 1.7 Hz, 2H), 6.32 (dd, J = 7.4, 4.2 Hz, 1H), 6.24 (s, 2H), 4.64 (t, J = 7.6 Hz, 1H), 4.23-4.15 (m, 2H), 4.02 (t, J = 6.7 Hz, 2H), 3.97 (dd, J = 11.5, 8.4 Hz, 1H), 3.73 (t, J = 10.8 Hz, 1H), 3.04-2.92 (m, 2H), 2.70 (s , 1H), 2.66 (dt, J = 13.7, 7.8 Hz, 1H), 2.57 (ddd, J = 13.6, 7.1, 4.2 Hz, 1H), 1.89 (s, 2H), 1.24 (d, J = 4.9 Hz, 30H), 0.87 (t, J = 6.8 Hz, 3H).

Step 4: Nonadecan-10-yl(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2- yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate nonadecan-10-yl L-phenylalaninate (1,840 mg, 4.26 mmol), triethylamine (0.594 mL, 4.26 mmol) in DCM (30 mL) To the cold (ice-water bath) solution was added a solution of phenylphosphorodichloridate (0.510 mL, 3.41 mmol) in DCM (1 mL) dropwise under nitrogen atmosphere, and then the reaction mixture was stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (500mg, 1.705mmol) To a cold (ice-water bath) solution of THF (20 mL)/pyridine (10 mL) was added tert-butylmagnesium chloride (4.26 mL, 4.26 mmol) dropwise under nitrogen atmosphere, and the mixture was then stirred at room temperature for 30 min. . The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. The solvent was removed under reduced pressure and the residue was diluted with EtOAc (200 mL) and water (50 mL). The organic phase was separated and the aqueous layer was extracted with EtOAc (20 mL x 2). The combined organic phases were washed with water (50 mL x 2), dried over Na ₂ SO ₄ and concentrated. The residue was purified by gel silica chromatography (80 g, MeOH:DCM=1:15) to give nonadecan-10-yl (((2R,3S,5R)-5-(6-amino-2-fluoro- 9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate (650 mg, 0.742 mmol, yield 43.5%) Obtained as a solid. LCMS (M+H) = 863.2; retention time (0.1% TF A) = 2.77, 2.83 min. Diastereomers were separated by preparative SFC (equipment: SFC-80 (Thar, Waters); column: OZ 20 x 250 mm, 10 μm (Daicel); column temperature: 40°C; mobile phase: CO ₂ /MeOH (0.2% ammonia /methanol) = 45/55; flow rate: 80 g/min; back pressure: 100 bar; detection wavelength: 260 nm; cycle time: 7.5 min; sample solution: 356 mg dissolved in 10 mL of methanol; injection volume: 1 .5 mL) and the first eluting isomer (Example 24A, RT 1: 1.71 min, 184.6 mg, 0.217 mmol, 99.36%, 26.8% yield) was separated by off-white Obtained as a solid; LCMS (M+H) = 863.2; retention time (0.1% TFA) = 3.39 min; ¹ H NMR (400 MHz, DMSO) δ 8.22 (s, 1H), 7.85 (brs, 2H) ), 7.27-7.19 (m, 4H), 7.18-7.08 (m, 4H), 7.04 (d, J = 8.4 Hz, 2H), 6.23 (dd, J = 7.6, 4.9 Hz, 1H), 6.09 (dd, J = 11.9, 10.9 Hz, 1H), 5.73 (d, J = 5.6 Hz, 1H), 4.68-4.60 (m, 1H), 4.51 (dd, J = 12.8, 7.0 Hz, 1H), 4.03-3.92 (m , 2H), 3.75 (dd, J = 10.9, 4.4 Hz, 1H), 3.61 (s, 1H), 2.98-2.89 (m, 1H), 2.78 (dd, J = 13.5, 8.3 Hz, 1H), 2.74- 2.66 (m, 1H), 2.46-2.39 (m, 1H), 1.31-1.00 (m, 32H), 0.83 (td, J = 6.9, 3.1 Hz, 6H), the second eluting isomer (Example 24B , RT2: 2.41 min, 133.7 mg, 0.155 mmol, 98.94%, yield: 19.1%) as an off-white solid. LCMS (M+H) = 863.5; retention time (0.1% TFA) = 3.34 min; ¹ H NMR (400 MHz, DMSO) δ 8.17 (s, 1H), 7.85 (s, 2H), 7.25- 7.16 (m, 5H), 7.15-7.07 (m, 3H), 6.99 (d, J = 8.4 Hz, 2H), 6.26 (dd, J = 7.3, 5.4 Hz, 1H), 6.13 (dd, J = 13.1, 10.6 Hz, 1H), 5.76 (d, J = 5.6 Hz, 1H), 4.66 (p, J = 6.0 Hz, 1H), 4.50 (dd, J = 12.5, 6.7 Hz, 1H), 3.99 (dd, J = 10.7, 5.2 Hz, 1H), 3.95-3.85 (m, 2H), 3.64 (s, 1H), 2.95-2.87 (m, 1H), 2.80 (dd, J = 13.5, 8.0 Hz, 1H), 2.70-2.62 (m, 1H), 2.46-2.37 (m, 1H), 1.30-0.98 (m, 32H), 0.83 (td, J = 6.9, 4.7 Hz, 6H).

Step 3: Henicosan-11-yl(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2- yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninatehenicosan -11-yl L-phenylalaninate (1.254 g, 2.73 mmol), triethylamine (0.380 mL, 2.73 mmol) in DCM (20 mL) To the solution was added a solution of phenylphosphorodichloridate (0.408 mL, 2.73 mmol) in DCM (1 mL) dropwise at about 5° C. under nitrogen atmosphere. The reaction mixture was then stirred at room temperature for 1 hour. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (0.4 g, 1. To a solution of 364 mmol) in THF (20 mL)/pyridine (10 mL), tert-butylmagnesium chloride (3.41 mL, 3.41 mmol) was added dropwise at 0° C. under a nitrogen atmosphere. The mixture was then stirred at room temperature for 30 minutes. The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. The mixture was filtered and concentrated to give a yellow solid. The solid was then dissolved in EtOAc (40 mL) and partitioned with HCl (0.05N, 20 mL). The layers were separated and the aqueous layer was extracted with EtOAc (30 mL x 2). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated to give the crude product. The residue was purified by reverse phase chromatography (SepaFlash® C18, 0-100% CH ₃ CN/10 mM NH ₄ HCO ₃ H ₂ O) to give heniicosan-11-yl (((2R,3S, 5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate ( 240 mg, 0.256 mmol, yield 18.77%) was obtained. LCMS: no mass; retention time (0.1% TFA) = 4.004, 4.097 min. Two consecutive preparative SFC purifications of diastereomers: 1st purification (equipment: SFC-150 (Waters), column: OX 20 x 250 mm, 10 μm (Daicel), column temperature: 35 °C; mobile phase: CO ₂ /MeOH (0.2% ammonia/methanol) = 55/45; flow rate: 100 g/min, back pressure: 100 bar; detection wavelength: 214 nm, cycle time: 4.5 min, sample solution: 280 mg in 40 mL methanol Injection volume: 2 mL) and second purification (equipment: SFC-150 (Waters), column: ID 20 x 250 mm, 10 μm (Daicel), column temperature: 35 °C; mobile phase: CO ₂ /MeOH ( 0.2% ammonia/methanol) = 55/45; flow rate: 120 g/min, back pressure: 100 bar; detection wavelength: 214 nm, cycle time: 5 min, sample solution: 220 mg dissolved in 40 mL methanol; injection volume : 2 mL) to obtain the first eluting isomer (Example 25A, RT 1: 1.08 min, 133 mg, 0.145 mmol, yield 32.3%); LCMS: retention time (0.1 % TFA) = 3.697 min; HPLC: Retention time (0.1% NH ₄ HCO ₃ ) = 12.652 min; ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.64 (s, 1H), 7.29 (dd , J = 11.0, 6.9 Hz, 3H), 7.25-7.20 (m, 2H), 7.18-7.13 (m, 5H), 6.29 (dd, J = 7.6, 4.1 Hz, 1H), 5.86 (s, 2H), 4.90-4.82 (m, 1H), 4.51 (t, J = 7.7 Hz, 1H), 4.19-4.11 (m, 1H), 4.70 (dd, J = 11.8, 10.0 Hz 1H), 3.72 (dd, J = 11.7 , 9.3 Hz, 1H), 3.63-3.38 (m, 2H), 3.07 (d, J = 10.8 Hz, 1H), 2.89 (dd, J = 13.6, 7.7 Hz, 1H), 2.69 (s, 1H), 2.67 -2.58 (m, 1H), 2.51-2.43 (m, 1H), 1.66 (s, 6H), 1.25-1.15 (m, 30H), 0.87 (dd, J = 6.9, 5.8 Hz, 6H), and second An isomer (Example 25B, RT2: 1.69 min, 100 mg, 0.107 mmol, yield 23.77%) was obtained; LCMS: Retention time (0.1% TFA) = 3.785 min. ; HPLC: Retention time (0.1% NH ₄ HCO ₃ ) = 13.150 minutes; ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.90 (s, 1H), 7.25-7.17 (m, 5H), 7.13 ( t, J = 6.8 Hz, 3H), 7.07 (d, J = 8.0 Hz, 2H), 6.30 (t, J = 5.7 Hz, 1H), 6.21 (s, 2H), 4.85-4.78 (m, 1H), 4.67 (dd, J = 12.8, 7.8 Hz, 1H), 4.32-4.25 (m, 1H), 4.25-4.13 (m, 2H), 3.90 (t, J = 10.7 Hz, 1H), 3.80 (d, J = 4.2 Hz, 1H), 3.06 (dd, J = 12.8, 5.6 Hz, 1H), 2.94 (dd, J = 13.9, 7.2 Hz, 1H), 2.71-2.65 (m, 3H), 1.92 (s, 4H), 1.25-1.15 (m, 32H), 0.87 (t, J = 7.2 Hz, 6H).

Step 3: Tetradecyl ((((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate To a cold (ice-water bath) solution of tetradecyl L-alaninate (1217 mg, 4.26 mmol), triethylamine (0.594 mL, 4.26 mmol) in DCM (30 mL) was added dropwise a solution of phenyl phosphorodichloridate (899 mg, 4.26 mmol) in DCM (1 mL) under nitrogen atmosphere, then the reaction mixture was stirred at room temperature for 1 h. To a cold (ice-water bath) solution of (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (500 mg, 1.705 mmol) in THF (20 mL)/pyridine (10 mL) was added tert-butylmagnesium chloride (4.26 mL, 4.26 mmol) dropwise under nitrogen atmosphere, and the mixture was then stirred at room temperature for 30 minutes. The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. The reaction mixture was quenched with water and partitioned between dichloromethane (100 mL) and water (100 mL). The organic phase was washed with water (100 mL), saturated brine (100 mL), dried over sodium sulfate, and evaporated in vacuo to give the crude product. The residue was purified by silica gel column (25 g, MeOH:DCM=10:1) to give tetradecyl((((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate (457 mg, 0.552 mmol, 32.4% yield) . LCMS (M+H)=717.1; retention time (0.1% TFA)=2.82 min. The diastereomers were separated by preparative SFC (instrument: SFC-80 (Thar, Waters); column: AD 20×250 mm, 10 μm (Daicel); column temperature: 40° C.; mobile phase: CO ₂ /ETOH (1.0% ammonia/methanol)=45/55; flow rate: 80 g/min; back pressure: 100 bar; detection wavelength: 214 nm; cycle time: 7.7 min; sample solution: 457 mg dissolved in 35 mL of methanol; injection volume: 3 mL) to give the first eluting isomer (Example 28A, RT1: 1.69 min, 148.5 mg, 0.224 mmol, 100%, 32.5% yield) as an off-white solid; LCMS (M+H)=717.1; retention time (0.1% TFA)=2.81 min; ¹ H NMR (400 MHz, DMSO) δ 8.24 (s, 1H), 7.84 (s, 2H), 7.32-7.27 (m, 2H), 7.13 (t, J = 7.4 Hz, 3H), 6.28 (dd, J = 7.6, 4.8 Hz, 1H), 5.98 (dd, J = 13.4, 10.1 Hz, 1H), 5.81 (d, J = 5.5 Hz, 1H), 4.65 (dd, J = 12.7, 7.1 Hz, 1H), 4.22 (dd, J = 10.8, 5.5 Hz, 1H), 4.10 (dd, J = 10.9, 4.5 Hz, 1H), 3.97-3.89 (m, 2H), 3.73-3.65 (m, 2H), 2.81-2.73 (m, 1H), 2.48-2.42 (m, 1H), 1.50-1.43 (m, 2H), 1.20 (d, J = 15.3 Hz, 22H), 1.13 (d, J = 7.0 Hz, 3H), 0.85 (t, J = 6.8 Hz, 3H), the second eluting isomer (Example 28B, RT2: 3.4 min, 154.8 mg, 0.231 mmol, 95.26%, 32.3% yield) was obtained as an off-white solid; LCMS (M+H) = 717.1; retention time (0.1% TFA) = 2.82 min; ^1H NMR (400 MHz, DMSO) δ 8.26 (s, 1H), 7.85. (s, 2H), 7.34-7.28 (m, 2H), 7.15 (dd, J = 14.3, 7.5 Hz, 3H), 6.26 (dd, J = 7.6, 4.9 Hz, 1H), 5.99 (dd, J = 13.1, 10.0 Hz, 1H), 5.78 (d, J = 5.4 Hz, 1H), 4.61 (dd, J = 12.5, 7.2 Hz, 1H), 4.24 (dd, J = 10.7, 5.9 Hz, 1H), 4.06 (dd, J = 10.8, 4.7 Hz, 1H), 3.97-3.90 (m, 1H), 3.87-3.76 (m, 2H), 3.63 (s, 1H), 2.79-2.70 (m, 1H), 2.47-2.42 (m, 1H), 1.48-1.41 (m, 2H), 1.24-1.19 (m, 23H), 1.17 (s, 2H), 0.85 (t, J = 6.8 Hz, 3H).

Step 2: Octadecyl L-Alaninate A mixture of octadecyl (tert-butoxycarbonyl)-L-alaninate (34.47 g, 78 mmol) in TFA (30 mL, 389 mmol) and DCM (150 mL) was stirred at 25° C. overnight. LCMS showed the presence of new product. The reaction was concentrated and the pH of the residue was adjusted to 8-9 with NaOH (1N). The mixture was extracted with DCM (100 mL x 3). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ and concentrated. The residue was purified by silica gel chromatography (DCM:MeOH=10:1) to give octadecyl L -alaninate (26 g, 76 mmol, 98% yield) as a white solid. LCMS (M+H) = 342.2; retention time (0.1% TFA) = 2.245 min; ¹ H NMR (400 MHz, CDCl ₃ ) δ: 4.12-4.08 (m, 2H), 3.55-3.54 (m , 1H), 1.68-1.61 (m, 4H), 1.34-1.33 (m, 5H), 1.33-1.22 (m, 28H), 0.89-0.86 (m, 3H).

Example 33: Tridecane-7-yl(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2 -yl)methoxy)(phenoxy)phosphoryl)alaninate

Step 2: Tridecan-7-yl L-alaninate A solution of tridecan-7-yl(tert-butoxycarbonyl)-L-alaninate (14.4 g, 38.8 mmol) and TFA (25 mL, 324 mmol) in DCM (125 mL) was stirred at 25° C. overnight. TLC showed that the starting material was consumed and a new compound was detected. The reaction mixture was concentrated, the pH of the residue was adjusted to 8 with 1N NaOH, and the resulting mixture was extracted with DCM (100 mL×3). The combined organic phase was washed with brine, dried over sodium sulfate, and concentrated to give a residue. The residue was purified by silica gel chromatography (petroleum ether: EtOAc = 20: 1-DCM: MeOH = 20: 1) to give tridecan-7-yl L-alaninate (10.3 g, 37.9 mmol, 98% yield) as a yellow oil . ^1H NMR: (400MHz, d6-DMSO): 4.93-4.87 (m, 1H), 3.84-3.79 (m, 1H), 1.55-1.53 (m, 4H), 1.50 (d, J = 7.2Hz, 3H), 1.22-1.26 (m, 16H), 0.88 (t, J = 6.8Hz, 6H).

Step 3: Tridecane-7-yl(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2- yl)methoxy)(phenoxy)phosphoryl)-L-alaninate tridecane -7-yl L-alaninate (2314 mg, 8.52 mmol), triethylamine (1.188 mL, 8.52 mmol) in DCM (40 mL) in a cold (ice water bath) solution. A solution of phenylphosphorodichloridate (1.274 mL, 8.52 mmol) in DCM (40 mL) was added dropwise under nitrogen atmosphere, and then the reaction mixture was stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (1000mg, 3.41mmol) To a cold (ice-water bath) solution of THF (30 mL)/pyridine (15 mL) was added tert-butylmagnesium chloride (8.52 mL, 8.52 mmol) dropwise under nitrogen atmosphere, and the mixture was then stirred at room temperature for 30 min. . The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. H ₂ O (20 mL) and EtOAc (30 mL) were added. The organic phase was separated and the aqueous layer was extracted with EtOAc (20 mL x 2). The organic phases were combined, washed with water (20 mL x 2), dried over Na ₂ SO ₄ and concentrated. The crude product was purified by silica gel chromatography (DCM:MeOH=10:1) to give tridecane-7-yl ( ((2R,3S,5R)-5-(6-amino-2-fluoro-9H- Purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate (320 mg, 0.450 mmol, yield 13.18%) was obtained . LCMS (M+H) = 703.3; retention time (0.1% TF A) = 2.04 min. Diastereomers were separated by preparative SFC (apparatus: SFC-150 (Waters); column: OX 20 x 250 mm, 10 μm (Daicel); column temperature: 35°C; mobile phase: CO ₂ /MeOH (0.2% ammonia/methanol). )=70/30; flow rate: 100 g/min; back pressure: 100 bar; detection wavelength: 214 nm; cycle time: 7 minutes; sample solution: 700 mg dissolved in 40 mL of methanol; injection volume: 2 mL). The first eluting isomer (Example 33A, RT1: 2.12 min, 100%) was obtained as an off-white solid; LCMS (M+H) = 703.3; Retention time (0.1% TFA) = 2.59 min; ¹ H NMR (400 MHz, DMSO) δ 8.23 (s, 1H), 7.82 (brs, 2H), 7.29 (t, J = 7.9 Hz, 2H), 7.13 (t, J = 8.8 Hz, 3H), 6.28 (dd, J = 7.6, 4.8 Hz, 1H), 5.94 (dd, J = 13.4, 10.3 Hz, 1H), 5.80 (d, J = 5.5 Hz, 1H), 4.75-4.60 (m, 2H) ), 4.21 (dd, J = 10.8, 5.6 Hz, 1H), 4.08 (dd, J = 10.9, 4.4 Hz, 1H), 3.73-3.63 (m, 2H), 2.80-2.72 (m, 1H), 2.48- 2.41 (m, 1H), 1.47-1.37 (m, 4H), 1.22-1.07 (m, 19H), 0.80 (dt, J = 17.3, 6.9 Hz, 6H), the second eluting isomer (Example 33B , RT2: 2.43 min, 98.25%) as an off-white solid; LCMS (M+H) = 703.3; retention time (0.1% TFA) = 2.60 min; ¹ H NMR (400 MHz, DMSO) δ 8.19 (s, 1H), 7.84 (brs, 2H), 7.33-7.27 (m, 2H), 7.20-7.12 (m, 3H), 6.26 (dd, J = 7.4, 5.1 Hz, 1H) , 5.98 (dd, J = 12.9, 10.3 Hz, 1H), 5.79 (d, J = 5.5 Hz, 1H), 4.75-4.68 (m, 1H), 4.59 (dd, J = 12.4, 6.8 Hz, 1H), 4.18 (dd, J = 10.7, 5.1 Hz, 1H), 4.10 (dd, J = 10.7, 5.1 Hz, 1H), 3.77-3.69 (m, 1H), 3.65 (s, 1H), 2.77-2.68 (m, 1H), 2.47-2.40 (m, 1H), 1.46-1.37 (m, 4H), 1.24-1.13 (m, 19H), 0.82 (td, J = 6.8, 1.7 Hz, 6H), the third eluting isomer LCMS (M+H) = 703.3; Retention time (0.1% TFA) = 2.61 min; ¹ H NMR (400 MHz, DMSO) δ 8.19 (s, 1H), 7.84 (brs, 2H), 7.33-7.27 (m, 2H), 7.20-7.12 (m, 3H), 6.26 (dd, J = 7.4, 5.1 Hz, 1H), 5.98 (dd, J = 12.9, 10.3 Hz, 1H), 5.79 (d, J = 5.5 Hz, 1H), 4.75-4.68 (m, 1H), 4.59 (dd, J = 12.4, 6.8 Hz, 1H), 4.18 (dd, J = 10.7, 5.1 Hz, 1H), 4.10 (dd, J = 10.7, 5.1 Hz, 1H), 3.77-3.69 (m, 1H), 3.65 (s, 1H), 2.77 -2.68 (m, 1H), 2.47-2.40 (m, 1H), 1.46-1.37 (m, 4H), 1.24-1.13 (m, 19H), 0.82 (td, J = 6.8, 1.7 Hz, 6H), 4 The first eluting isomer (Example 33D, RT4: 3.95 min, 99.54%) was obtained as an off-white solid; LCMS (M+H) = 703.3; retention time (0.1% TFA) = 2.62 min; ¹ H NMR (400 MHz, DMSO) δ 8.19 (s, 1H), 7.84 (brs, 2H), 7.33-7.27 (m, 2H), 7.20-7.12 (m, 3H), 6.26 ( dd, J = 7.4, 5.1 Hz, 1H), 5.98 (dd, J = 12.9, 10.3 Hz, 1H), 5.79 (d, J = 5.5 Hz, 1H), 4.75-4.68 (m, 1H), 4.59 (dd , J = 12.4, 6.8 Hz, 1H), 4.18 (dd, J = 10.7, 5.1 Hz, 1H), 4.10 (dd, J = 10.7, 5.1 Hz, 1H), 3.77-3.69 (m, 1H), 3.65 ( s, 1H), 2.77-2.68 (m, 1H), 2.47-2.40 (m, 1H), 1.46-1.37 (m, 4H), 1.24-1.13 (m, 19H), 0.82 (td, J = 6.8, 1.7 Hz, 6H).

Step 4: Pentadecane-8-yl(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2- yl)methoxy)(phenoxy)phosphoryl)-L-alaninatepentadecane -8-yl L-alaninate (4.09 g, 13.64 mmol), triethylamine (1.901 mL, 13.64 mmol) in DCM ( 6 mL) in cold (ice water) To the solution was added dropwise a solution of phenylphosphorodichloridate (2.88 g, 13.64 mmol) in DCM (1 mL) under nitrogen atmosphere, and then the reaction mixture was stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (2g, 6.82mmol) To a cold (ice-water bath) solution of THF (4 mL)/pyridine (2 mL) was added tert-butylmagnesium chloride (17.05 mL, 17.05 mmol) dropwise under a nitrogen atmosphere, and the mixture was stirred at room temperature for 30 minutes. The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred at -20°C for 60 hours. LCMS showed the presence of new product. The cold (ice-water bath) reaction mixture was quenched with saturated NH ₄ Cl (20 mL), filtered, and concentrated. The filtrate was extracted with EtOAc (30 mL x 2). The combined organic phases were washed with saturated NaCl (20 mL), dried over Na ₂ SO ₄ and concentrated. The residue was purified by reverse phase _column chromatography (120 g, _CH3CN / _{10mM NH4HCO3H2O} =1:3). The appropriate fractions were combined and the solvent removed in vacuo to give pentadecane-8-yl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl). )-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate (350 mg, 0.464 mmol, yield 6.80%) was obtained as a white solid. LCMS: no mass, retention time (0.1% TFA) = 2.77 minutes. Diastereomers were separated by preparative SFC (apparatus: SFC-150 (Waters); column: OX 20 x 250 mm, 10 μm (Daicel); column temperature: 35°C; mobile phase: CO ₂ /MeOH (0.2% ammonia/methanol). )=60/40; flow rate: 100 g/min; back pressure: 100 bar; detection wavelength: 214 nm; cycle time: 5 minutes; sample solution: 580 mg dissolved in 60 mL of methanol; injection volume: 2 mL). The first eluting isomer (Example 34A, RT1: 1.40 min, 180 mg, 0.242 mmol, 30.4% yield) was obtained as a white solid; retention time (0.1% TFA) = 2 .164 min, m/z = 731.2 (M+H); HPLC: retention time (0.1% NH ₄ HCO ₃ ) = 12.438 min; ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.83 (s, 1H), 7.28 (d, J = 8.3 Hz, 1H), 7.25-7.22 (m, 1H), 7.19 (d, J = 8.0 Hz, 2H), 7.12 (t, J = 7.2 Hz, 1H), 6.45 ( s, 2H), 6.34 (dd, J = 7.2, 4.2 Hz, 1H), 4.85 (p, J = 6.2 Hz, 1H), 4.73 (t, J = 7.6 Hz, 1H), 4.39 (d, J = 8.2 Hz, 2H), 4.22-3.89 (m, 3H), 2.74 (s, 1H), 2.73-2.59 (m, 2H), 1.49 (d, J = 4.5 Hz, 4H), 1.35 (d, J = 6.7 Hz) , 3H), 1.21 (d, J = 6.4 Hz, 20H), 0.88-0.82 (m, 6H), second eluting isomer (Example 34B, RT2: 2.42 min, 156 mg, 0.207 mmol, Yield 26.0%) was obtained as a white solid; Retention time (0.1% TFA) = 2.189 min, m/z = 731.3 (M+H); HPLC: Retention time (0.1% NH) ₄ HCO ₃ ) = 12.549 min; ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.98 (s, 1H), 7.24 (s, 1H), 7.17 (d, J = 8.3 Hz, 2H), 7.11 (t , J = 7.3 Hz, 1H), 6.82 (s, 2H), 6.33 (t, J = 5.7 Hz, 1H), 4.88-4.79 (m, 2H), 4.46-4.24 (m, 4H), 4.06-3.95 ( m, 1H), 2.76-2.66 (m, 3H), 1.46 (d, J = 6.1 Hz, 4H), 1.36 (d, J = 7.0 Hz, 3H), 1.20 (t, J = 15.3 Hz, 20H), 0.83 (td, J = 6.8, 3.3 Hz, 6H).

Step 3: Tricosan-12-yl(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2- yl)methoxy)(phenoxy)phosphoryl)-L-alaninatetricosan -12-yl L-alaninate (3.37 g, 8.18 mmol), triethylamine (1.141 mL, 8.18 mmol) in a cold solution of DCM (50 mL). A solution of phenylphosphorodichloridate (1.223 mL, 8.18 mmol) in DCM (1 mL) was added dropwise at approximately 5° C. under a nitrogen atmosphere, and the reaction mixture was then stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (1.2 g, 4. To a cold solution of 0.09 mmol) in THF (20 mL)/pyridine (10 mL) was added tert-butylmagnesium chloride (10.23 mL, 10.23 mmol) dropwise at 0° C. under nitrogen atmosphere. The mixture was then stirred at room temperature for 30 minutes. The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the presence of product. The mixture was filtered and concentrated to give a yellow solid. The solid was then dissolved in EtOAc, filtered, and concentrated to give the crude product. The residue was purified by reverse phase chromatography (SepaFlash® C18 column, 0-100% CH ₃ CN/10 mM NH ₄ HCO ₃ H ₂ O) to give tricosan-12-yl (((2R,3S ,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-alaninate (850 mg , 0.972 mmol, yield 23.76 %) as a yellow solid. LCMS: Retention time (0.1% TFA) = 4.004, 4.097 minutes. Diastereomers were separated by preparative SFC (apparatus: SFC-80 (Thar, Waters); column: OX 20 x 250 mm, 10 μm (Daicel); column temperature: 35°C; mobile phase: CO ₂ /MeOH (0.2% ammonia). /methanol) = 55/45; flow rate: 100 g/min; back pressure: 100 bar; detection wavelength: 214 nm; cycle time: 4 min; sample solution: 880 mg dissolved in 30 mL of methanol and DCM). , the first eluting isomer (Example 38A, RT1: 1.2 min, 296 mg, 0.338 mmol, 40.7% yield) was obtained as a white solid; LCMS: Retention time (0.1% TFA) = 3.907 minutes; HPLC: retention time (0.1% TFA) = 13.606 minutes; ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.79 (s, 1H), 7.31 (t, J = 7.9 Hz, 2H ), 7.21 (d, J = 7.7 Hz, 2H), 7.15 (t, J = 7.3 Hz, 1H), 6.35 (dd, J = 7.0, 4.7 Hz, 1H), 6.05 (s, 2H), 4.87 (d , J = 6.2 Hz, 1H), 4.72 (t, J = 7.5 Hz, 1H), 4.38 (d, J = 8.9 Hz, 2H), 4.00 (dd, J = 15.8, 8.1 Hz, 1H), 3.86-3.62 (m, 2H), 2.75 (s, 1H), 2.72-2.62 (m, 2H), 1.76 (s, 4H), 1.36 (d, J = 7.0 Hz, 3H), 1.26-1.20 (m, 36H), 0.87 (t, J = 6.8 Hz, 6H), the second eluting isomer (Example 38B, RT2: 2.56 min, 168 mg, 0.197 mmol, 23.73% yield) was obtained as a white solid. ; LCMS (M+H) = 843.4; Retention time (0.1% TFA) = 3.983 min; HPLC: Retention time (0.1% TFA) = 13.942 min; ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.95 (s, 1H), 7.31-7.27 (m, 2H), 7.18 (d, J = 8.6 Hz, 2H), 7.15 (t, J = 7.3 Hz, 1H), 6.33 (dd, J = 7.4 , 4.2 Hz, 1H), 6.00 (s, 2H), 4.86 (dd, J = 11.7, 5.8 Hz, 2H), 4.36 (ddd, J = 20.6, 11.3, 8.7 Hz, 2H), 4.03 (dd, J = 16.1, 9.0 Hz, 1H), 3.91-3.84 (m, 1H), 3.71 (s, 1H), 2.81-2.67 (m, 3H), 1.77 (s, 4H), 1.40 (d, J = 7.0 Hz, 3H ), 1.26-1.18 (d, J = 14.5 Hz, 36H), 0.87 (t, J = 6.9 Hz, 6H).

Step 1: Hexadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate hexadecane -1-ol (8.85 g, 36.5 mmol), (S)- A solution of 2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoic acid (10 g, 33.2 mmol) and HATU (18.93 g, 49.8 mmol) in DCM (100 mL) Imidazole (6.78 g, 100 mmol) and DIPEA (17.39 mL, 100 mmol) were added. The resulting mixture was stirred at 25°C overnight. TLC (petroleum ether:EtOAc=10:1, Rf=0.5) showed completion of the reaction. The reaction was quenched with water (100 mL) and DCM (50 mL) and the organic layer was separated. The aqueous layer was extracted with DCM (2 x 50 mL). The combined organic layers were washed with brine (200 mL), dried over Na ₂ SO ₄ and concentrated to give the crude product. The residue was purified by combiflash (silica gel column 330 g, hexane:ethyl acetate=20:1). Appropriate fractions containing the product are combined and the solvent is removed in vacuo to give hexadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate (8. 5 g, 16.17 mmol, yield 48.7%) was obtained as a yellow solid. ¹ H NMR (400 MHz, MeOD) δ 6.87 (d, J = 6.6 Hz, 2H), 6.82 (dd, J = 14.9, 5.6 Hz, 1H), 4.37 (dd, J = 9.2, 5.8 Hz, 1H), 4.13 (t, J = 6.5 Hz, 2H), 3.15 (dd, J = 13.8, 5.7 Hz, 1H), 2.94 (dd, J = 13.7, 9.4 Hz, 1H), 1.67-1.57 (m, 2H), 1.41 (s, 9H), 1.37 (d, J = 12.3 Hz, 2H), 1.31 (s, 24H), 0.92 (t, J = 6.8 Hz, 3H).

Step 2: Hexadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate To a solution of hexadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate (8.5 g, 16.17 mmol) in DCM (100 mL) was added TFA (7.47 mL, 97 mmol). The resulting mixture was stirred at 25° C. for 2 h. TLC (petroleum ether: EtOAc = 10:1, Rf = 0.05) showed the reaction was complete. The reaction was diluted with water (200 mL) and DCM (100 mL). The organic layer was separated and the aqueous layer was extracted with DCM (2×100 mL). The combined organic layers were washed with brine (50 mL), dried over Na ₂ SO ₄ and concentrated to give crude hexadecyl (S)-2-amino-3-(3,5- difluorophenyl )propanoate (6.3 g, 14.80 mmol, 92% yield), which was used in the next step without purification.

Step 3: Hexadecyl (2S)-2-((((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran -2-yl)methoxy)(phenoxy)phosphoryl)amino)-3-(3,5-difluorophenyl)propanoate hexadecyl (S)-2-amino-3-(3,5- difluorophenyl )propanoate (3. 99 g, 9.38 mmol) and triethylamine (1.307 mL, 9.38 mmol) in DCM (60 mL, ice water bath) under nitrogen atmosphere. A DCM (10 mL) solution was added dropwise and the reaction mixture was then stirred at room temperature for 1 hour. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (1.1 g, 3. To a cold (ice-water bath) solution of 75 mmol) in THF (30 mL)/pyridine (15 mL) was added dropwise tert-butylmagnesium chloride (9.38 mL, 9.38 mmol) under a nitrogen atmosphere, and the mixture was stirred at room temperature for 30 minutes. . The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. The mixture was filtered and concentrated to give a yellow solid. The solid was then dissolved in EtOAc (40 mL) and partitioned with HCl (0.05N, 20 mL). The layers were separated and the aqueous layer was extracted with EtOAc (40 mL). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated to give the crude product. The residue was purified by combiflash (silica gel column 20 g, DCM:MeOH=24:1). Appropriate fractions containing the product were combined and the solvent removed in vacuo to give hexadecyl(2S)-2-(((((2R,3S,5R)-5-(6-amino-2-fluoro- 9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)amino)-3-(3,5-difluorophenyl)propanoate (500 mg, 0.583 mmol, Yield: 15.56%) was obtained as a yellow solid. LCMS (M+H) = 857.1; retention time (0.1% TFA) = 2.52 minutes. Diastereomers were separated by SFC (equipment: SFC-80 (Thar, Waters), column: OZ 20 x 250 mm, 10 μm (Daicel), column temperature: 40°C, mobile phase: CO ₂ /ETOH (1.0% ammonia/methanol). ) = 60/40; flow rate: 80 g/min; back pressure: 100 bar; detection wavelength: 259 nm; cycle time: 9 min) to separate the first eluting isomer (Example 39A, RT1: 1.67 min, 200 mg, 0.233 mmol, yield 40.0%) as a white solid; LCMS (M+H) = 857.3; Retention time (0.1% TFA) = 2.512 min; HPLC: Retention time ( 0.1% TFA) = 13.439 min; ¹ H NMR (400 MHz, DMSO) δ 8.18 (s, 1H), 7.84 (s, 2H), 7.22 (t, J = 7.9 Hz, 2H), 7.09 ( t, J = 7.4 Hz, 1H), 6.97 (s, 1H), 6.95 (s, 1H), 6.88 (d, J = 6.3 Hz, 2H), 6.26 (dd, J = 7.4, 5.1 Hz, 1H), 6.15 (dd, J = 12.3, 10.5 Hz, 1H), 5.78 (d, J = 5.5 Hz, 1H), 4.55 (dd, J = 12.6, 6.9 Hz, 1H), 4.02 (dd, J = 9.8, 5.2 Hz , 2H), 3.93 (ddd, J = 13.8, 10.8, 4.2 Hz, 3H), 3.64 (s, 1H), 2.95 (d, J = 11.0 Hz, 1H), 2.80 (dd, J = 13.7, 9.0 Hz, 1H), 2.69 (dd, J = 12.0, 6.3 Hz, 1H), 2.43 (dd, J = 13.6, 7.2 Hz, 2H), 1.43 (s, 2H), 1.19 (d, J = 23.9 Hz, 26H), 0.85 (t, J = 6.8 Hz, 3H), the second eluting isomer (Example 39B, RT2: 2.82 min, 200 mg, 0.233 mmol, yield 40.0%) was obtained as a white solid. ; LCMS (M+H) = 857.3; Retention time (0.1% TFA ) = 2.512 min; _HPLC : Retention time (0.1% _NH4HCO3 ) = 13.736 min; LCMS (M+H ) = 857.3; Retention time (0.1% TFA) = 2.52 minutes; HPLC: Retention time (0.1% TFA ) = 13.39 minutes; ¹ H NMR (400 MHz, DMSO) δ 8.22 (s, 1H), 7.83 (s, 2H), 7.25 (t, J = 7.9 Hz, 2H), 7.11 (t, J = 7.2 Hz, 1H), 7.01 (d, J = 8.5 Hz, 2H), 6.91 (d, J = 8.6 Hz, 2H), 6.23 (dd, J = 7.6, 4.8 Hz, 1H), 6.14 (dd, J = 12.7, 10.6 Hz, 1H), 5.74 (d, J = 5.6 Hz, 1H ), 4.52 (dd, J = 12.9, 7.2 Hz, 1H), 4.06 (dd, J = 10.8, 6.4 Hz, 1H), 3.98 (dd, J = 9.4, 6.0 Hz, 1H), 3.89-3.83 (m, 1H), 3.82-3.75 (m, 1H), 3.60 (s, 1H), 3.36 (dd, J = 11.7, 6.5 Hz, 1H), 2.96 (dd, J = 12.1, 4.6 Hz, 1H), 2.80 (dd , J = 13.5, 9.1 Hz, 1H), 2.73-2.65 (m, 1H), 2.43 (dd, J = 13.5, 7.5 Hz, 2H), 1.40-1.35 (m, 2H), 1.23 (d, J = 4.9 Hz, 26H), 0.86-0.83 (m, 3H).

Step 1: Octadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate octadecane -1-ol (8.98 g, 33.2 mmol), (S)- 2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoic acid (10 g, 33.2 mmol), imidazole (6.78 g, 100 mmol), DIPEA (17.39 mL, 100 mmol) and A mixture of HATU (18.93 g, 49.8 mmol) in DCM (500 mL) was stirred at 25° C. for 16 hours. TLC showed the presence of new product. Water (500 mL) was added and the resulting mixture was extracted with DCM (250 mL x 3). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (petroleum ether:EtOAc=30:1) to give octadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl )propanoate. (16 g, 28.9 mmol, 87% yield) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO) δ 7.34-6.98 (m, 3H), 4.21-4.01 (m, 3H), 3.03-2.84 (m, 3H), 2.83 (qd, J = 13.5, 7.0 Hz, 2H) , 1.49 (s, 3H), 1.39 (s, 9H), 1.23 (s, 30H), 0.84 (t, J = 6.8 Hz, 3H).

Step 2: Octadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Octadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl ) To a solution of propanoate (16 g, 28.9 mmol) in DCM (100 mL) was added TFA (95 mL, 1228 mmol) at 25°C. The reaction mixture was stirred at 25°C for 4 hours. TLC showed complete consumption of starting material. The reaction was concentrated to dryness, the pH of the residue was adjusted to 5-6 with Na ₂ CO ₃ solution, and then extracted with DCM (200 mL×3). The combined organic layers were washed with brine, dried _{over Na2SO4} , filtered, and concentrated. The residue was purified by silica gel chromatography to give octadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (8.0 g, 17.63 mmol, yield 61.0%). ¹ H NMR (400 MHz, DMSO) δ 7.14- 6.83 (m, 3H), 4.08-3.85 (m, 2H), 3.60 (t, J = 6.9 Hz, 1H), 2.83 (qd, J = 13.5, 7.0 Hz , 2H), 1.48 (d, J = 6.6 Hz, 2H), 1.23 (s, 30H), 0.85 (t, J = 6.8 Hz, 3H).

Step 1: Icosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate icosan- 1-ol (9.91 g, 33.2 mmol), (S)- 2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoic acid (10 g, 33.2 mmol), imidazole (6.78 g, 100 mmol), DIPEA (17.39 mL, 100 mmol) and A solution of HATU (18.93 g, 49.8 mmol) in DCM (500 mL) was stirred at 25° C. for 16 hours. TLC showed the presence of new product. Water (500 mL) was added and the reaction mixture was extracted with DCM (250 mL x 3). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (petroleum ether:EtOAc=30:1) to give icosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl )propanoate. (14 g, 24.0 6 mmol, yield 72.5%) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO) δ 7.36-7.34 (m, 1H), 7.06-6.98 (m, 3H), 4.02-3.99 (m, 3H), 2.88 (m, 3H), 1.51-1.48 (m, 2H), 1.32 (s, 9H), 1.27 (S, 34H), 0.86-0.83 (m, 3H).

Step 2: Icosyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate To a solution of Icosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl) propanoate (14 g, 24.06 mmol) in DCM (50 mL) was added TFA (50 mL, 649 mmol) at 25 °C. The reaction mixture was stirred at 25 °C for 4 h. TLC showed the reaction was complete. The reaction was concentrated to dryness. The pH of the residue was adjusted to 5-6 with Na ₂ CO ₃ solution and extracted with DCM (100 mL × 3). The combined organic layers were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography to give icosyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (8 g, 16.61 mmol, 69.0% yield). ^1H NMR (400 MHz, DMSO) δ 7.11- 6.84 (m, 3H), 3.98 (dd, J = 11.6, 5.9 Hz, 2H), 3.60 (t, J = 6.9 Hz, 1H), 2.94- 2.72 (m, 2H), 2.07 (s, 2H), 1.47 (s, 2H), 1.23 (s, 34H), 0.84 (d, J = 6.8 Hz, 3H).

Step 1: docosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate docosan- 1-ol (10.84 g, 33.2 mmol), (S)- 2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoic acid (10 g, 33.2 mmol), imidazole (6.78 g, 100 mmol), DIPEA (17.39 mL, 100 mmol) and A mixture of HATU (18.93 g, 49.8 mmol) in DCM (500 mL) was stirred at 25° C. for 16 hours. TLC showed the presence of new product. Water (500 mL) was added and the reaction mixture was extracted with DCM (250 mL x 3). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (petroleum ether:EtOAc=30:1) to give docosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl )propanoate. (16 g, 26.2 mmol, 79% yield) was obtained as a white solid. ¹ H NMR (400 MHz, DMSO) δ 7.36-7.34 (m, 1H), 7.06-6.98 (m, 3H), 4.03-4.00 (m, 3H), 3.00-2.68 (m, 3H), 1.51-1.48 ( m, 2H), 1.32 (s, 9H), 1.27 (S, 38H), 0.86-0.83 (m, 3H).

Step 2: Docosyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate docosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl ) To a solution of propanoate (10 g, 16.40 mmol) in DCM (50 mL) was added TFA (1.263 mL, 16.40 mmol) at 0<0>C. The mixture was then warmed to room temperature and stirred for 2 hours. TLC showed completion of the reaction. The pH of the reaction mixture was adjusted to 7-8 with saturated Na ₂ CO ₃ solution and extracted with DCM (100 mL×3). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated to give a residue. The residue was purified by silica gel chromatography (DCM:MeOH=20:1) to give docosyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (8 g, 14.91 mmol, yield 91 %) was obtained. ¹ H NMR (400 MHz, DMSO) δ 7.00 (d, J = 34.2 Hz, 3H), 5.76 (s, 1H), 3.99 (s, 2H), 3.62 (s, 1H), 2.83 (s, 2H), 1.47 (s, 2H), 1.23 (s, 38H), 0.85 (s, 3H).

Step 3: Icosyl ((((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate To a cold (ice-water bath) solution of Icosyl L-phenylalaninate (7.60 g, 17.05 mmol) and triethylamine (2.376 mL, 17.05 mmol) in DCM (48 mL), a solution of phenyl phosphorodichloridate (3.60 g, 17.05 mmol) in DCM (1 mL) was added dropwise in ice water under a nitrogen atmosphere, and the reaction mixture was then stirred at room temperature for 1 hour. To a solution of (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (2 g, 6.82 mmol) in THF (24 mL)/pyridine (12 mL) was added tert-butylmagnesium chloride (17.05 mL, 17.05 mmol) dropwise under nitrogen at 0° C., then the mixture was warmed to room temperature and stirred for 30 minutes. The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. The reaction mixture was filtered and concentrated, then the residue was diluted with DCM. Water was added to the mixture and extracted. The organic layer was then washed with 0.5 N HCl (3 times) and brine. The organic phase was dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by flash chromatography (0-5% MeOH/DCM) to give icosyl ((((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate (800 mg, 0.867 mmol, 12.71% yield). LCMS (M+H) = 877.7 ; retention time (0.1% TFA) = 3.82 min. The diastereomers were separated by preparative SFC (instrument: SFC-80 (Thar, Waters), column: OZ 20×250 mm, 10 μm (Daicel), column temperature: 60° C., mobile phase: CO ₂ /ETOH (1.0% ammonia/methanol)=60/40; flow rate: 80 g/min; back pressure: 100 bar; detection wavelength: 260 nm; cycle time: 9 min) to give the first eluting isomer (Example 43A, RT1: 1.35 min, 125.8 mg, 0.1434 mmol, 100.0%, 16.79% yield) as an off-white solid; LCMS (M+H)=877.7, retention time (0.1% TFA)=3.82 min; HPLC: retention time (0.1% NH ₄ HCO ₃ )=13.350 min; ¹ H NMR (400 MHz, MeOD) δ 8.14 (d, J = 18.6 Hz, 1H), 7.33-7.18 (m, 5H), 7.16- 6.99 (m, 5H), 6.42-6.28 (m, 1H), 4.76-4.65 (m, 1H), 4.17 (dt, J = 37.1, 18.6 Hz, 1H), 4.02 (ddd, J = 23.5, 12.5, 5.9 Hz, 4H), 2.98 (dt, J = 15.3, 7.5 Hz, 1H), 2.86 (dd, J = 11.8, 6.5 Hz, 1H), 2.80-2.59 (m, 2H), 1.47 (dd, J = 18.5, 12.9 Hz, 2H), 1.39 -1.08 (m, 36H), 0.91 (t, J = 6.4 Hz, 3H), the second eluting isomer (Example 43B, RT2: 2.04 min, 207.5 mg, 0.2366 mmol, 99.56%, 17.10% yield) was obtained as an off-white solid; LCMS (M+H) = 877.7, retention time (0.1% TFA) = 3.84 min; HPLC: retention time (0.1% _{NH4HCO3 )} = 12.581 min; ^1H NMR (400 MHz, MeOD) δ 8.06-7.96 (m, 1H), 7.18- 6.89 (m, 10H), 6.24-6.12 (m, 1H), 4.58 (t, J = 7.5 Hz, 1H), 4.04-3.94 (m, 2H), 3.91-3.73 (m, 3H), 3.08- 3.03 (m, 1H), 2.91 (ddd, J = 13.5, 6.3, 2.2 Hz, 1H), 2.84-2.40 (m, 3H), 1.4-1.27 (m, 2H), 1.23-1.08 (m, 36H), 0.79 (t, J = 6.9 Hz, 3H).

Step 2: AcOH (1.386 mL, 24.21 mmol) was added. A solution of 12,12,13,13,14,14,15,15,15-nonafluoro-10-iodopentadecane-1-ol (50 g, 97 mmol) in ethanol (10.0 mL) was stirred for 1 hour. was added dropwise and the reaction mixture was heated at 50° C. for 4 hours. TLC showed the presence of new compound. The reaction mixture was concentrated to dryness. The pH of the residue was adjusted to 5-6 with aqueous Na ₂ CO ₃ and extracted with E tOAc (50 mL×3). The combined organic layers were washed with brine, dried _{over Na2SO4} , _filtered , and concentrated. The crude product was purified by silica gel chromatography to give 12,12,13,13,14,14,15,15,15-nonafluoropentadecane-1-ol (21 g, 53.8 mmol, 55.5% yield) ) was obtained. ¹ H NMR (400 MHz, CDCl ₃ ): δ 3.54 (t, J = 17.0, 6.8 Hz, 2H), 2.16-2.12 (m, 2H), 1.62-1.51 (m, 4H), 1.33 (s, 14H) .

Step 5: 12,12,13,13,14,14,15,15,15-nonafluoropentadecyl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purine) -9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate 12,12,13,13,14,14,15,15,15- Phenylphosphorodichloride was added to a cold (ice-water bath) solution of nonafluoropentadecyl L-phenylalaninate (7.33 g, 13.64 mmol) and triethylamine (1.901 mL, 13.64 mmol) in DCM (48 mL) under a nitrogen atmosphere. Date (2.88 g, 13.64 mmol) in DCM (1 mL) was added dropwise and the reaction mixture was then stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (2.0 g, 6. To a solution of 82 mmol) in THF (24 mL)/pyridine (12 mL) was added tert-butylmagnesium chloride (13.64 mL, 13.64 mmol) dropwise under nitrogen atmosphere, and the mixture was then stirred at room temperature for 30 minutes. The first prepared mixture was added dropwise to the second prepared mixture at room temperature, and the mixture was stirred at room temperature for 2 hours. LCMS showed the reaction was complete. The reaction mixture was filtered and the filtrate was concentrated. The residue was then diluted with DCM and washed with water, 0.5N HCl (3x), brine, dried over _Na2SO4 , filtered, and concentrated _. The residue was purified by silica gel chromatography (0-5% MeOH/DCM) to give 12,12,13,13,14,14,15,15,15-nonafluoropentadecyl (((2R,3S, 5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate ( 1 g, 1.032 mmol, yield 15.13%). LCMS (M+H) = 969.7; retention time (0.1% TFA) = 2.15 minutes. Diastereomers were separated by preparative SFC (equipment: SFC-80 (Thar, Waters), column: AS 20 x 250 mm, 10 μm (Daicel), column temperature: 40°C, mobile phase: CO ₂ /MeOH (0.2% ammonia). /methanol) = 70/30; flow rate: 70 g/min; back pressure: 100 bar; detection wavelength: 260 nm; cycle time: 6.5 min; sample solution: 510 mg dissolved in 12 mL of methanol; injection volume: 2 mL ) to give the first eluting isomer (Example 44A, RT 1: 1.66 min, 100.5 mg, 0.127 mmol, 98.59%, 16.79% yield) as an off-white solid. Obtained; LCMS (M+H) = 969.7; Retention time (0.1% TFA) = 2.76 minutes; HPLC: Retention time (10mM NH ₄ HCO ₃ ) = 7.911 minutes; ¹ H NMR (400 MHz, DMSO) δ 8.24 (d, J = 8.9 Hz, 1H), 7.85 (s, 2H), 7.35-7.07 (m, 8H), 7.02 (d, J = 8.4 Hz, 2H), 6.23 (dd, J = 7.5 , 4.9 Hz, 1H), 6.14-6.00 (m, 1H), 5.74 (d, J = 5.6 Hz, 1H), 4.52 (dd, J = 12.6, 7.2 Hz, 1H), 3.89 (dddd, J = 42.6, 35.9, 14.2, 9.5 Hz, 5H), 3.63 (d, J = 8.9 Hz, 1H), 2.99-2.85 (m, 1H), 2.84-2.63 (m, 2H), 2.18 (dd, J = 18.2, 10.0 Hz , 2H), 1.50 (dd, J = 15.5, 7.8 Hz, 2H), 1.38-1.28 (m, 4H), 1.18 (d, J = 15.8 Hz, 13H), the second eluting isomer (Example 44B , RT2: 2.77 min, 85.5 mg, 0.107 mmol, 97.28%, yield: 14.10%) was obtained as an off-white solid; LCMS (M+H) = 969.7; retention time ( 0.1% TFA) = 2.75 minutes; HPLC: retention time (10mM NH ₄ HCO ₃ ) = 7.876 minutes; ¹ H NMR (400 MHz, DMSO) δ 8.20 (s, 1H), 7.85 (s, 2H), 7.29-7.16 (m, 5H), 7.11 (dd, J = 7.2, 3.2 Hz, 3H), 6.98 (d, J = 8.5 Hz, 2H), 6.28 (dd, J = 7.2, 5.2 Hz, 1H ), 6.20-6.06 (m, 1H), 5.78 (d, J = 5.5 Hz, 1H), 4.54 (dd, J = 12.5, 6.8 Hz, 1H), 4.11-3.92 (m, 2H), 3.95-3.79 ( m, 3H), 3.66 (s, 1H), 2.88 (d, J = 7.1 Hz, 1H), 2.80 (dd, J = 13.5, 7.9 Hz, 1H), 2.75-2.64 (m, 1H), 2.19 (s , 2H), 1.56-1.42 (m, 2H), 1.35 (d, J = 6.8 Hz, 4H), 1.27-1.07 (m, 13H).

Step 5: 7,7,8,8,9,9,10,10,11,11,12,12,12-tridecafluorododecyl (((2R,3S,5R)-5-(6-amino -2-Fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate 7,7,8,8,9, 9,10,10,11,11,12,12,12-tridecafluorododecyl L-phenylalaninate (5804 mg, 10.23 mmol) and triethylamine (3.56 mL, 25.6 mmol) in cold DCM (60 mL) To the ice-water bath solution was added phenylphosphorodichloridate (5396 mg, 25.6 mmol) in DCM (60 mL) dropwise under nitrogen atmosphere, and then the reaction mixture was stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (3000mg, 10.23mmol) To a cold (ice-water bath) solution of THF (60 mL)/pyridine (30 mL) was added tert-butylmagnesium chloride (25.6 mL, 25.6 mmol) dropwise under a nitrogen atmosphere, and the mixture was then stirred at room temperature for 30 min. . The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. NH ₄ Cl solution was added to the residue to adjust the pH to 7, the organic layer was separated and the aqueous layer was extracted with DCM (300 mL). The combined organic layers were washed with 0.5N HCl (100 mL, 3 times) and brine, dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (0-5% MeOH/DCM) to give 7,7,8,8,9,9,10,10,11,11,12,12,12-tridecafluorododecyl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl )-L-phenylalaninate (462 mg, 0.463 mmol, yield 4.52%) was obtained. LCMS (M+H) = 999.0; retention time (0.1% TFA) = 2.03 minutes. Diastereomers were separated by preparative SFC (equipment: SFC-80 (Thar, Waters), column: IG 20 x 250 mm, 10 μm (Daicel), column temperature: 40°C, mobile phase: CO ₂ /IPA (0.2% ammonia). /methanol) = 55/45; flow rate: 80 g/min; back pressure: 100 bar; detection wavelength: 260 nm; cycle time: 6 min) to separate the first eluting isomer (Example 45A, 1.46 min, 134.2 mg, 0.134 mmol, 100%, yield 16.79%) obtained as an off-white solid; LCMS (M+H) = 999.7; retention time (0.1% TFA) = 2.60 min ; HPLC: Retention time (0.05% TFA) = 12.070 minutes; ¹ HNMR (400 MHz, DMSO) δ 8.20 (s, 1H), 8.00- 7.71 (m, 2H), 7.32- 6.84 (m, 10H) ), 6.35- 6.22 (m, 1H), 6.21- 6.05 (m, 1H), 5.87- 5.74 (m, 1H), 4.62- 4.43 (m, 1H), 4.08- 3.95 (m, 2H), 3.95- 3.78 (m, 3H), 3.66 (s, 1H), 2.95- 2.61 (m, 3H), 2.30- 2.00 (m, 2H), 1.50- 1.02 (m, 9H), the second eluting isomer (Example 45B, RT2: 2.15 min, 155.1 mg, 0.155 mmol, 100%, yield 14.10%) was obtained as an off-white solid; LCMS (M+H) = 999.7; retention time (0. 1% TFA) = 2.60 min; HPLC: Retention time (0.05% TFA) = 12.048 min; ¹ H NMR (400 MHz, DMSO) δ 8.20 (s, 1H), 8.00-7.74 (m, 2H), 7.32- 6.71 (m, 10H), 6.28 (dd, J = 7.4,5.1 Hz, 1H), 6.14 (dd, J = 13.0, 10.4 Hz, 1H), 5.79 (d,J = 5.5 Hz, 1H ), 4.55 (d, J = 5.7 Hz, 1H), 4.09-3.96 (m, 2H), 3.92- 3.81 (m, 3H), 3.66 (s, 1H), 2.78 (ddd,J = 50.3, 17.6, 6.9 Hz, 3H), 2.15 (d, J = 8.1Hz,2H), 1.58- 1.02 (m, 9H).

Step 5: 5,5,6,6,7,7,8,8,8-nonafluorooctyl (((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purine- 9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate 5,5,6,6,7,7,8,8,8-nona Phenylphosphorodichloridate ( 2.88 g, 13.63 mmol) was added dropwise to DCM (60 mL) and the reaction mixture was then stirred at room temperature for 1 h. (2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3-ol (1.997 g, 6. To a cold (ice-water bath) solution of 81 mmol) in THF (40 mL)/pyridine (20 mL) was added dropwise tert-butylmagnesium chloride (13.63 mL, 13.63 mmol) under a nitrogen atmosphere, and the mixture was then stirred at room temperature for 30 min. Stirred. The first prepared mixture was added dropwise to the second prepared mixture at room temperature and stirred for 2 hours. LCMS showed the reaction was complete. The reaction mixture was filtered and the filtrate was concentrated. The residue was diluted with DCM, washed with water, 0.5N HCl (3x), brine, dried over _Na2SO4 , filtered, and _concentrated . The residue was purified on a silica gel column (0-5% MeOH/DCM) to give 5,5,6,6,7,7,8,8,8-nonafluorooctyl (((2R,3S,5R) -5-(6-amino-2-fluoro-9H-purin-9-yl)-2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)-L-phenylalaninate (1. 2 g, 1.378 mmol, yield 20.24%). LCMS (M+H) = 871.7; retention time (0.1% TFA) = 1.85 min. Diastereomers were separated by preparative SFC (equipment: SFC-80 (Thar, Waters), column: OZ 20 x 250 mm, 10 μm (Daicel), column temperature: 40°C, mobile phase: CO ₂ /MEOH (0.2% ammonia). /methanol) = 70/30; flow rate: 80 g/min; back pressure: 100 bar; detection wavelength: 260 nm; cycle time: 6 min) to separate the first eluting isomer (Example 46A, RT 1:2 .07 min, 100.0 mg, 0.114 mmol, 98.71%, 16.79% yield) was obtained as an off-white solid; LCMS (M+H) = 871.7; retention time (0.1% TFA) = 1.85 min; HPLC: retention time (0.05% TFA) = 10.761 min; ¹ H NMR (400 MHz, DMSO) δ 8.20 (s, 1H), 8.00-7.74 (m, 2H), 7.32 - 6.71 (m, 10H), 6.28 (dd, J = 7.4, 5.1 Hz, 1H), 6.14 (dd, J = 13.0, 10.4 Hz, 1H), 5.79 (d, J = 5.5 Hz, 1H), 4.55 ( d, J = 5.7 Hz, 1H), 4.09 - 3.96 (m, 2H), 3.92- 3.81 (m, 3H), 3.66 (s, 1H), 2.78 (ddd, J = 50.3, 17.6, 6.9 Hz, 3H) , 2.15 (d, J = 8.1 Hz, 2H), 1.58 -1.02 (m, 9H), second eluting isomer (Example 46B, RT2: 2.96 min, 148.0 mg, 0.169 mmol, 98 .1%, yield 14.10%) as an off-white solid; LCMS (M+H) = 871.7; retention time (0.1% TFA) = 2.35 min; HPLC: retention time (0.1%, yield 14.10%) as an off-white solid; .05% TFA) = 10.7 6 9 minutes; ¹ H NMR (400 MHz, DMSO). HPLC: Retention time (0.05% TFA) = 10.769 min. δ 8.20 (s, 1H), 8.00- 7.74 (m, 2H), 7.32- 6.71 (m, 10H), 6.28 (dd, J = 7.4, 5.1 Hz, 1H), 6.14 (dd, J = 13.0, 10.4 Hz, 1H), 5.79 (d, J = 5.5 Hz, 1H ), 4.55 (d, J = 5.7 Hz, 1H), 4.09- 3.96 (m, 2H), 3.92- 3.81 (m, 3H), 3.66 (s, 1H), 2.78 (ddd, J = 50.3, 17.6, 6.9 Hz, 3H), 2.15 (d, J = 8.1 Hz, 2H), 1.58- 1.02 (m, 9H).

Step 1: Nonadecyl(tert-butoxycarbonyl)-L-phenylalaninate Stirring (tert-butoxycarbonyl)-L-phenylalanine (26.6 g, 100 mmol) and EDC (24.96 g, 130 mmol) in DCM (150 mL) ) DMAP (1.224 g, 10.02 mmol) was added to the mixture at 0°C. After 30 minutes, nonadecan-1-ol (28.5 g, 100 mmol) was added and the resulting reaction mixture was stirred at 25° C. for 16 hours. TLC showed the reaction was complete. The reaction mixture was diluted with water (80 mL) and extracted with DCM (100 mL x 2). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ and concentrated. The residue was purified by silica gel chromatography (petroleum ether:EtOAc=10:1) to give nonadecyl(tert-butoxycarbonyl)-L-phenylalaninate (42 g, 79 mmol, 79% yield) as a yellow oil. Obtained. ¹ H NMR (400 MHz, CDCl3) δ 7.30-7.23 (m, 3H), 7.14-7.12 (m, 2H), 4.99-4.97 (m, 1H), 4.57-4.55 (m, 1H), 4.09-4.05 ( m, 2H), 3.09-3.06 (t, J = 6.8 Hz, 3H), 1.61-1.55 (t, J = 6.8 Hz, 3H), 1.41 (s, 9H), 1.29 (bs, 30H), 0.86 (t , J = 6.8 Hz, 3H).

Step 3: Nonadecyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate To a stirred solution of nonadecyl L-phenylalaninate (31 g, 71.8 mmol) in anhydrous DCM (50 mL), Triethylamine ( 10.98 mL, 79 mmol) was added dropwise over 15 minutes at -70°C. To this mixture was added a solution of phenylphosphorodichloridate (15.00 g, 71.1 mmol) in anhydrous DCM (30 mL) over 1 hour. The reaction mixture was stirred at this temperature for 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added a solution of 2,3,4,5,6-pentafluorophenol (13.09 g, 71.1 mmol) and triethylamine (10.98 mL, 79 mmol) in DCM (20 mL) over 20 minutes. The crude mixture was stirred at 0°C for 4 hours. TLC showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (50 mL). The filtrate was concentrated under reduced pressure, the resulting residue was triturated with THF (250 mL), and the solid (triethylamine hydrochloride) was filtered off. The cake was washed with THF (2 x 50 mL) and the combined filtrates were concentrated under reduced pressure. The crude product was triturated with EtOAc (200 mL) and filtered to give nonadecyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate (20 g, 21.22 mmol, 29.6% yield) ) was recovered as a white solid (>98% de as determined by ³¹ PNMR). ¹ H NMR (400 MHz, CDCl3) δ 7.41 - 7.27 (m, 2H), 7.25 - 7.15 (m, 5H), 7.15 - 6.98 (m, 3H), 4.43 (d, J = 5.8 Hz, 1H), 4.13 - 3.96 (m, 2H), 3.84 - 3.74 (m, 1H), 3.10 (ddd, J = 20.0, 13.7, 5.8 Hz, 2H), 1.54 (s, 2H), 1.36 - 1.08 (m, 32H), 0.88 (t, J = 6.8 Hz, 3H). ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.54.

Step 1: Henicosyl(tert-butoxycarbonyl)-L-phenylalaninate Stirred (tert-butoxycarbonyl)-L-phenylalanine (5 g, 18.85 mmol), HOBt (3.82 g, 28.3 mmol) and EDC To a mixture of (4.34 g, 22.62 mmol) in DCM (150 mL) was added TEA (2.63 mL, 18.85 mmol) at 0<0>C. After stirring for 30 minutes, henicosan-1-ol (5.89 g, 18.85 mmol) was added and the resulting reaction mixture was stirred at 25° C. for 16 hours. TLC showed the reaction was complete. The reaction mixture was diluted with water (80 mL) and extracted with DCM (100 mL x 2). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (petroleum ether: EtOAc = 10:1) to obtain henicosyl(tert-butoxycarbonyl)-L-phenylalaninate (6.1 g, 10.90 mmol, yield 57.8%). Obtained as a yellow oil. ¹ H NMR (400 MHz, CDCl3) δ 7.30-7.22 (m, 3H), 7.14-7.12 (m, 2H), 4.99-4.97 (m, 1H), 4.57-4.55 (m, 1H), 4.09-4.05 ( m, 2H), 3.09-3.06 (t, J = 6.8 Hz, 3H), 1.61-1.55 (t, J = 6.8 Hz, 3H), 1.41 (s, 9H), 1.25 (bs, 32H), 0.85 (t , J = 6.8 Hz, 3H).

Step 2: Henicosyl L-phenylalaninate To a stirred solution of henicosyl (tert-butoxycarbonyl)-L-phenylalaninate (6.1 g, 10.90 mmol) in DCM (50 mL) was added TFA (25 mL, 324 mmol) at 0° C. After 5 min, the mixture was warmed to 25° C. and stirred for 2 h. TLC showed the presence of a new product. The reaction mixture was concentrated, the residue was diluted with water (50 mL), the pH was adjusted to 8-9 with saturated Na ₂ CO ₃ , and extracted with DCM (50 mL×3). The combined organic phase was washed with brine (80 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (DCM:MeOH=100:0-20:1) to give henicosyl L-phenylalaninate (4.56 g, 9.92 mmol, 91% yield). ^1H NMR (400 MHz, CDCl3 ₎ δ 7.34 - 7.27 (m, 2H), 7.26 - 7.16 (m, 3H), 4.09 (dd, J = 8.6, 4.8 Hz, 2H), 3.72 (dd, J = 7.8, 5.4 Hz, 1H), 3.08 (dd, J = 13.5, 5.4 Hz, 1H), 2.87 (dd, J = 13.5, 7.8 Hz, 1H), 1.58 (s, 2H), 1.25 (bs, 36H), 0.88 (t, J = 6.8 Hz, 3H).

Step 3: Henicosyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate Stirred solution of henicosyl L-phenylalaninate (4.5 g, 9.79 mmol) in anhydrous DCM (50 mL) To the solution, triethylamine (1.497 mL, 10.77 mmol) was added dropwise at −70° C. over 15 minutes. To the reaction mixture was added a solution of phenylphosphorodichloridate (2.044 g, 9.69 mmol) in anhydrous DCM (30 mL) over 1 hour. The reaction mixture was stirred at -70°C for 30 minutes, then warmed to 0°C over 2 hours and stirred for 1 hour. To this mixture was added a solution of 2,3,4,5,6-pentafluorophenol (1.784 g, 9.69 mmol) and triethylamine (1.497 mL, 10.77 mmol) in DCM (20 mL) over 20 minutes. . The crude mixture was stirred at 0°C for 4 hours. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (50 mL). The filtrate was concentrated under reduced pressure and the residue was triturated with tert-butyl methyl ether (250 mL). Solid triethylamine hydrochloride was filtered off. The cake was washed with tert-butyl methyl ether (2 x 50 mL) and the combined filtrates were concentrated under reduced pressure. The crude product was triturated with 20% EtOAc in hexanes (200 mL) and the solid was collected by filtration to give henicosyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate (2 .2 g, 2.64 mmol, 27.0% yield) was obtained as a white solid (>94% de as determined by ³¹ PNMR). ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.35 (t, J = 7.9 Hz, 2H), 7.26 - 7.14 (m, 6H), 7.05 (dd, J = 7.0, 2.4 Hz, 2H), 4.50 - 4.36 ( m, 1H), 4.04 (ddd, J = 10.7, 8.7, 4.0 Hz, 2H), 3.87 - 3.76 (m, 1H), 3.10 (ddd, J = 20.0, 13.7, 5.8 Hz, 2H), 1.54 (s, 2H), 1.25 (s, 36H), 0.88 (t, J = 6.8 Hz, 3H). ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.54.

Step 1: Pentadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl)amino) To a solution of -3-(3,5-difluorophenyl)propanoic acid (4 g, 13.28 mmol) in DCM (50 mL) was added DMAP (0.162 g, 1.328 mmol) and EDC (3.31 g, 17.26 mmol). Added at 0°C. After 30 minutes, pentadecane-1-ol (3.94 g, 17.26 mmol) was added and the resulting reaction mixture was stirred at 25° C. for 2 hours. LCMS showed the reaction was complete. The reaction mixture was diluted with water (40 mL) and extracted with DCM (2x100 mL). The combined organic layers were washed with brine (40 mL), dried _over Na _SO , filtered, and concentrated to give pentadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3, 5- difluorophenyl )propanoate (5.8 g, 11.33 mmol, 85% yield) was obtained as a yellow oil, which was used in the next step without further purification. LCMS: (M+Na) = 534.2; retention time (0.1% TFA) = 3.19 minutes.

Step 2: Pentadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirred pentadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (5.8 g, 11.33 mmol) in DCM (50 mL) was added TFA (15 mL, 195 mmol) at 0°C. The resulting reaction mixture was stirred at 25°C for 4 hours. LCMS showed the reaction was complete. The reaction was concentrated and the residue was diluted with NaHCO ₃ (30 mL) and extracted with DCM (3×80 mL). The combined organic layers were washed with brine (50 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate = 2/1) to obtain pentadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (4.5 g, 10.93 mmol). , yield 96%) as a pale yellow oil. LCMS (M+H) = 412.4; retention time (0.05% TFA) = 2.01 min.

Step 1: Undecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl)amino) To a solution of -3-(3,5-difluorophenyl)propanoic acid (5 g, 16.60 mmol) in DCM (80 mL) was added DMAP (0.203 g, 1.660 mmol) and EDC (4.14 g, 21.57 mmol). Added at 0°C. After 30 minutes, undecane-1-ol (3.72 g, 21.57 mmol) was added at 0° C. and the resulting reaction mixture was stirred at 25° C. for 4 hours. LCMS showed the reaction was complete. The reaction mixture was diluted with water (50 mL) and extracted with DCM (2x100 mL). The combined organic layers were washed with brine (40 mL), dried over Na ₂ SO ₄ , filtered, and concentrated to give undecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3, 5- Difluorophenyl )propanoate (6.9 g, 15.15 mmol, 91% yield) was obtained as a yellow solid, which was used in the next step without further purification. LCMS: (M+Na) = 478.1; retention time (0.1% TFA) = 2.80 minutes.

Step 2: Undecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate To a stirred solution of undecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl )propanoate (6.9 g, 15.15 mmol) in DCM (60 mL) was added TFA (15 mL, 195 mmol) at 0° C. The resulting reaction mixture was stirred at 25° C. for 4 h. LCMS showed the reaction was complete. The reaction mixture was concentrated under reduced pressure and the residue was diluted with NaHCO ₃ (20 mL)/water (50 mL) and extracted with DCM (3×100 mL). The combined organic layers were washed with brine (60 mL), dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate=2/1) to give undecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (3.8 g, 10.52 mmol, 69.4% yield) as a yellow solid: LCMS (M+H)=356.3; retention time (0.05% TFA)=1.78 min.

Step 1: Tridecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl)amino) To a solution of -3-(3,5-difluorophenyl)propanoic acid (4 g, 13.28 mmol) in DCM (60 mL) was added DMAP (0.162 g, 1.328 mmol) and EDC (3.31 g, 17.26 mmol). Added at 0°C. After 30 minutes, tridecane-1-ol (3.46 g, 17.26 mmol) was added and the resulting reaction mixture was stirred at 25° C. for 4 hours. LCMS showed the reaction was complete. The reaction mixture was diluted with water (50 mL) and extracted with DCM (2x100 mL). The combined organic phases were washed with brine (40 mL), dried _over Na _SO , filtered, concentrated to give tridecyl(S)-2-((tert-butoxycarbonyl)amino)-3-(3, 5- difluorophenyl )propanoate (5.7 g, 11.79 mmol, 89% yield) was obtained as a yellow solid, which was used in the next step without further purification. LCMS: (M+Na) = 506.2; retention time (0.1% TFA) = 3.15 minutes.

Step 2: Tridecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirring tridecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (5.7 g, 11.79 mmol) in DCM (50 mL) was added TFA (12 mL, 156 mmol) dropwise at 0°C. The resulting reaction mixture was stirred at 25°C for 4 hours. LCMS showed the reaction was complete. The reaction mixture was concentrated under reduced pressure. The residue was diluted with NaHCO ₃ (20 mL)/water (50 mL) and extracted with DCM (3×100 mL). The combined organic layers were washed with brine (60 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate = 2/1) to obtain tridecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (2.6 g, 6.56 mmol). , yield 55.7%) as a pale yellow solid. LCMS (M+H) = 384.4; retention time (0.05% TFA) = 1.88 min.

Step 3: Tridecyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate Stirring tridecyl(S)-2- To a solution of amino-3-(3,5-difluorophenyl)propanoate (2.6 g, 6.78 mmol) in DCM (60 mL) was added triethylamine (1.037 mL, 7.46 mmol) dropwise at -70°C. To this mixture was added dropwise a solution of phenylphosphorodichloridate (1.416 g, 6.71 mmol) in anhydrous DCM (10 mL). The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added dropwise a solution of 2,3,4,5,6-pentafluorophenol (1.248 g, 6.78 mmol) and triethylamine (1.037 mL, 7.46 mmol) in DCM (15 mL). The resulting mixture was stirred at 0°C for 4 hours. LCMS showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (1 x 10 mL). The filtrate was concentrated under reduced pressure, the residue was triturated with tert-butyl methyl ether (120 mL) , and triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (2 x 30 mL) and the filtrate was concentrated under reduced pressure. The residue was triturated with 15% EtOAc in hexane (50 mL) and the solid was collected by filtration to give tridecyl(S)-3-(3,5-difluorophenyl)-2-(((S)- (Perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (1.1 g, 1.559 mmol, 22.99% yield) was obtained as a white solid (>98% de as determined by ³¹ PNMR). LCMS (M+H) = 706.3; retention time (0.05% TFA) = 3.40 minutes. ^31P NMR (CDCl ₃ , 162 MHz) δ -1.58.

Step 1: Heptadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl)amino) To a solution of -3-(3,5-difluorophenyl)propanoic acid (4 g, 13.28 mmol) in DCM (80 mL) was added DMAP (0.162 g, 1.328 mmol) and EDC (3.31 g, 17.26 mmol). Added at 0°C. After 30 minutes, heptadecan-1-ol (4.43 g, 17.26 mmol) was added and the resulting reaction mixture was stirred at 25° C. for 16 hours. LCMS showed the reaction was complete. The reaction mixture was diluted with water (50 mL) and extracted with DCM (2 x 100 mL). The combined organic layers were washed with brine (50 mL), dried over Na _SO , _filtered , and concentrated to give heptadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3, 5- difluorophenyl )propanoate (6.3 g, 11.67 mmol, 88% yield) was obtained as a yellow solid, which was used in the next step without further purification. LCMS: (M+Na) ⁺ =563.2; retention time (0.1% TFA) = 4.62 minutes.

Step 2: Heptadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirred heptadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (5.8 g, 10.75 mmol) in DCM (100 mL) was added TFA (20 mL, 260 mmol) dropwise at 0°C. The resulting reaction mixture was stirred at 25°C for 4 hours. LCMS showed the reaction was complete. The reaction was concentrated and the residue was neutralized with NaHCO ₃ (40 mL) and extracted with DCM (3×100 mL). The combined organic layers were washed with brine (50 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate = 1/1) to obtain heptadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (4.4 g, 10.01 mmol). , yield 93%) as a pale yellow solid. LCMS (M+H) = 440.2; retention time (0.1% TFA) = 2.31 min.

Step 3: Heptadecyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate Stirred heptadecyl (S)-2- To a solution of amino-3-(3,5-difluorophenyl)propanoate (4.4 g, 10.01 mmol) in DCM (100 mL) was added triethylamine (1.530 mL, 11.01 mmol) dropwise at -70°C. To this mixture was added dropwise a solution of phenylphosphorodichloridate (2.090 g, 9.91 mmol) in anhydrous DCM (10 mL). The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added dropwise a solution of 2,3,4,5,6-pentafluorophenol (1.842 g, 10.01 mmol) and triethylamine (1.530 mL, 11.01 mmol) in DCM (20 mL). The crude mixture was stirred at 0°C for 16 hours. LCMS showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (1 x 30 mL). The filtrate was concentrated under reduced pressure, the residue was triturated with tert-butyl methyl ether (200 mL) , and triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (2 x 20 mL) and the filtrate was concentrated under reduced pressure. The residue was triturated with 15% EtOAc in hexane (80 mL) and the solid was collected by filtration to give heptadecyl (S)-3-(3,5-difluorophenyl)-2-(((S)- (Perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (1.6 g, 2.100 mmol, 20.99% yield) was obtained as a white solid (>98% de as determined by ³¹ P NMR). LCMS (M+H) = 762.1; retention time (0.1% TFA) = 4.70 minutes. ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.60.

Step 1: Dodecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate stirred (S)-2-((tert-butoxycarbonyl)amino) -3-(3,5-difluorophenyl)propanoic acid (5 g, 16.60 mmol), dodecan-1-ol (3.09 g, 16.60 mmol) and EDC (4.14 g, 21.57 mmol) in DCM (50 mL) ) To the solution was added N,N-dimethylpyridin-4-amine (2.027 g, 16.60 mmol) at 0°C. The resulting reaction mixture was stirred at 25°C for 16 hours. LCMS showed the reaction was complete. The mixture was diluted with water (80 mL) and extracted twice with DCM (100 mL). The combined organic phases were washed twice with brine (100 mL), dried _{over Na} SO and concentrated to give dodecyl(S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (5.6 g, 11.92 mmol, 71.9% yield) was obtained as a white solid, which was used in the next step without further purification. LCMS (M+Na) = 492.1; retention time (0.1% TFA) = 2.954.

Step 2: Dodecyl (S)-2-amino-3-(3,5-difluorophenyl) propanoate Dodecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (5.6 g, 11.92 mmol) in DCM (50 mL) was added TFA (10 mL) at 0°C. The mixture was stirred at room temperature for 16 hours. LCMS showed the reaction was complete. The mixture was concentrated under vacuum to remove most of the DCM and TFA. Ice water (20 mL) was added, pH was adjusted to 7 with aqueous _NaHCO3 , and extracted with EtOAc (50 mL x 2). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ and concentrated. The crude product was purified by flash chromatography (silica gel, 80 g, petroleum ether:EtOAc=3:1) to give dodecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (4 g, 7 .01 mmol, yield 58.8%) was obtained as a white solid. LCMS (M+H) = 370.1; Retention time (0.1% TFA) = 1.965.

Step 3: Dodecyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate Stirred dodecyl(S)-2- To a solution of amino-3-(3,5-difluorophenyl)propanoate (4 g, 10.83 mmol) in DCM (50 mL) was added triethylamine (1.580 mL, 11.37 mmol) dropwise at −70° C. over 15 minutes. To this mixture was added a solution of phenylphosphorodichloridate (2.261 g, 10.72 mmol) in anhydrous DCM (35 mL) dropwise over 30 minutes. The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added a solution of 2,3,4,5,6-pentafluorophenol (1.973 g, 10.72 mmol) and triethylamine (1.655 mL, 11.91 mmol) in DCM (30 mL) over 20 minutes. . LCMS showed the reaction was complete. The crude mixture was stirred at 0° C. for 4 hours and the white solid (triethylamine hydrochloride) was filtered off and washed with DCM (250 mL). The filtrate was concentrated under reduced pressure, the residue was triturated with tert-butyl methyl ether (150 mL) , and triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (100 mL) and the filtrate was concentrated. The solid was triturated with petroleum ether:EtOAc=5:1 (20:4 mL), filtered, and washed with petroleum ether:EtOAc=5:1 (40:8 mL) to give dodecyl(S)-3- (3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (700 mg, 1.012 mmol, yield 9.35%) was obtained as a white solid ( >98% de) as determined by ³¹ PNMR. LCMS (M+H) = 691.0; retention time ( _{10mM NH4HCO3} ) = 3.010 minutes. ¹ H NMR (400 MHz, DMSO) δ 7.31 (t, J = 7.9 Hz, 2H), 7.18 (t, J = 7.3 Hz, 1H), 7.03-6.99 (m, 3H), 6.94 (t, J = 6.4 Hz, 2H), 4.15 (qd, J = 10.3, 5.5 Hz, 1H), 4.00 (t, J = 6.4 Hz, 2H), 3.09-3.00 (m, 1H), 2.85 (dd, J = 13.7, 9.7 Hz , 1H), 1.47 (d, J = 7.0 Hz, 2H), 1.21 (t, J = 12.7 Hz, 18H), 0.83 (t, J = 6.8 Hz, 3H). ³¹ PNMR (DMSO-d6, 162 MHz) δ 0.21.

Step 1: Nonadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl)amino) To a solution of -3-(3,5-difluorophenyl)propanoic acid (5 g, 16.60 mmol) and nonadecan-1-ol (4.72 g, 16.60 mmol) in DCM (50 mL) was added EDC (4.14 g, 21 .57 mmol) and N,N-dimethylpyridin-4-amine (2.027 g, 16.60 mmol) were added at 0°C. The resulting reaction mixture was stirred at 25°C for 16 hours. TLC showed the reaction was complete. The mixture was concentrated under vacuum and the residue was taken up in EtOAc (50 mL) and washed with water (30 mL). The aqueous layer was back-extracted with EtOAc (30 mL x 2) and the combined organic phases were washed twice with brine (80 mL), dried over Na ₂ SO ₄ and concentrated to obtain nonadecyl (S)-2-(( tert-Butoxycarbonyl)amino)-3-(3,5- difluorophenyl )propanoate (5 g, 8.81 mmol, 53.1% yield) was obtained as a white solid, which was carried on to the next step without further purification. It was used in LCMS (M+Na) = none; retention time (0.1% TFA) = none.

Step 2: Nonadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirred nonadecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (5 g, 8.81 mmol) in DCM (50 mL) was added TFA (10 mL) at 0°C. The mixture was stirred at 25°C for 16 hours. LCMS showed the reaction was complete. The mixture was concentrated under vacuum to remove most of the DCM and TFA. The residue was diluted with ice water (20 mL), the pH was adjusted to 7 with aqueous _NaHCO3 , and extracted with EtOAc (50 mL x 2). The combined organic phases were washed with brine (50 mL), dried over Na ₂ SO ₄ and concentrated. The crude product was purified by flash chromatography (silica gel, 80 g, petroleum ether:EtOAc=3:1) to give nonadecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (3.6 g , 7.70 mmol, yield 87%) was obtained as a white solid. LCMS (M+H) = 468.1; Retention time (0.1% TFA) = 2.387.

Step 3: Nonadecyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate Stirred nonadecyl (S)-2- To a solution of amino-3-(3,5-difluorophenyl)propanoate (3 g, 6.41 mmol) in DCM (50 mL) was added triethylamine (0.936 mL, 6.74 mmol) dropwise at −70° C. over 15 minutes. To this mixture was added a solution of phenylphosphorodichloridate (1.340 g, 6.35 mmol) in anhydrous DCM (35 mL) dropwise over 30 minutes. The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added a solution of 2,3,4,5,6-pentafluorophenol (1.169 g, 6.35 mmol) and triethylamine (0.981 mL, 7.06 mmol) in DCM (30 mL) over 20 min. Stirred at 0°C for 4 hours. LCMS showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (250 mL). The filtrate was concentrated under reduced pressure, the residue was triturated with tert-butyl methyl ether (150 mL) , and triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (100 mL). The solid was triturated with petroleum ether:EtOAc=5:1 (25:5 mL), filtered and washed with petroleum ether:EtOAc=5:1 (40:8 mL) to obtain nonadecyl(S)-3- (3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (1.1 g, 1.393 mmol, yield 21.71%) was obtained as a white solid. (>98% de as determined by ³¹ PNMR). ¹ H NMR (400 MHz, DMSO) δ 7.24 (d, J = 53.4 Hz, 3H), 6.97 (d, J = 27.4 Hz, 5H), 3.99 (s, 2H), 3.07 (s, 2H), 2.86 ( ³¹ PNMR (DMSO-d6, 162 MHz) δ 0.16.

Step 1: Tetradecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate stirred (S)-2-((tert-butoxycarbonyl)amino) In a mixture of -3-(3,5-difluorophenyl)propanoic acid (5 g, 16.60 mmol) in DCM (10 mL), DMAP (0.203 g, 1.660 mmol), tetradecane-1-ol (4.63 g, 21.60 mmol) and EDC (4.14 g, 21.61 mmol) in DCM (40 mL) were added at 0<0>C. The mixture was stirred at room temperature for 2 hours. LCMS showed the presence of new product. The reaction mixture was diluted with water (30 mL) and extracted with DCM (15 mL x 3). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ and concentrated. The crude product was purified by silica gel chromatography (120 g, petroleum ether:EtOAc=30:1) to give tetradecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl). ) Propanoate (7.2 g, 14.02 mmol, 85% yield) was obtained as a white solid. LCMS (M+Na) = 386.1; retention time ( _{10mM NH4HCO3} ) = 2.319 minutes.

Step 2: Tetradecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirred tetradecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (7.2 g, 14.47 mmol) in DCM (50 mL) was added TFA (11.15 mL, 145 mmol). The resulting mixture was stirred at 5°C for 3 hours. LCMS showed the reaction was complete. The pH was adjusted to about 8 with 1M NaOH (1 mol/L) and the organic phase was separated. The aqueous layer was extracted with DCM (20 mL x 2). The combined organic phases were washed with water (30 mL x 2), brine (30 mL x 2), dried over Na ₂ SO ₄ and concentrated. The crude product was purified by silica gel chromatography (120 g, Santai, DCM:MeOH=10:1) to give tetradecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (3.7 g, 7.86 mmol, yield 54.3%) was obtained as a white solid. LCMS (M+H) = 398.4; retention time (0.1% TFA) = 2.59 minutes.

Step 3: Tetradecyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate Stirring Tetradecyl(S)-2- To a solution of amino-3-(3,5-difluorophenyl)propanoate (3.7 g, 9.31 mmol) in anhydrous DCM (35 mL) was added Et ₃ N (1.362 mL, 9.77 mmol) at -70 °C for 15 min. It dripped. To this mixture was added a solution of phenylphosphorodichloridate (1.944 g, 9.21 mmol) in anhydrous DCM (35 mL) dropwise over 1 hour. The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added a solution of Et ₃ N (1.427 mL, 10.24 mmol) and 2,3,4,5,6-pentafluorophenol (1.696 g, 9.21 mmol) in DCM (30 mL) over 20 min. added. The reaction mixture was stirred at this temperature for 45 minutes. LCMS showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (1 x 25 mL). The filtrate was concentrated under reduced pressure. The residue was triturated with tert-butyl methyl ether (25 mL) and triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (25 mL) and the combined filtrates were concentrated under reduced pressure. The crude solid was triturated with petroleum ether:EtOAc=5:1 (30:6 mL), filtered, and washed with petroleum ether:EtOAc=5:1 (40:8 mL) to obtain tetradecyl(S)-3. -(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (1.2 g, 1.667 mmol, yield 17.92%) as a white solid. (>98% de as determined by ³¹ PNMR). LCMS (M+H) = 719.1; retention time (0.1% TFA) = 3.57 minutes. ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.60.

Step 1: Henicosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl)amino) To a mixture of -3-(3,5-difluorophenyl)propanoic acid (3.7 g, 12.28 mmol) in DCM (20 mL) was added DMAP (0.150 g, 1.228 mmol) at 0 °C, and the mixture was Stirred at ℃ for 0.5 hour. A solution of henicosan -1-ol (5.00 g, 15.98 mmol) and EDC (3.07 g, 15.9 mmol) in DCM (40 mL) was added at 0°C. The mixture was stirred at room temperature for 2 hours. LCMS showed the reaction was complete. The reaction mixture was diluted with water (50 mL) and extracted with DCM (30 mL x 3). The combined organic phases were washed with brine, dried _over Na SO and concentrated to give henicosyl ( _S )-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl ) . Propanoate (7 g, 11.75 mmol) was obtained which was used in the next step without further purification.

Step 2: Heneicosyl (S)-2-amino-3-(3,5-difluorophenyl) propanoate Stirred heneicosyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5 -difluorophenyl )propanoate (7 g, 11.75 mmol) in DCM (50 mL) was added TFA (9.05 mL, 117 mmol). The resulting mixture was stirred at 5°C for 2.5 hours. LCMS showed the reaction was complete. The pH of the reaction mixture was adjusted to ~8 with 1M NaOH, and the organic phase was washed with saturated NaCl (50 mL), dried (Na ₂ SO ₄ ), and concentrated. The crude product was purified by silica gel chromatography (120 g, Santai, DCM:MeOH=50:1) to give heneicosyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (4.4 g, 8.63 mmol, yield 73.5%) was obtained as an oil. LCMS (M+H) = 496.5; retention time (0.1% TFA) = 3.41 min.

Step 3: Henicosyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate Stirred Henicosyl(S)-2- To a solution of amino-3-(3,5-difluorophenyl)propanoate (4.4 g, 8.88 mmol) in anhydrous DCM (50 mL) was added triethylamine (1.299 mL, 9.32 mmol) at -75 °C over 15 min. dripped. To this mixture was added a solution of phenylphosphorodichloridate (1.854 g, 8.79 mmol) in anhydrous DCM (50 mL) dropwise over 1 hour. The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added a solution of triethylamine (1.361 mL, 9.76 mmol) and 2,3,4,5,6-pentafluorophenol (1.617 g, 8.79 mmol) in DCM (30 mL) over 20 minutes. . The mixture was stirred at 0° C. for 16 hours and at room temperature for 1 hour. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (1 x 25 mL). The filtrate was concentrated under reduced pressure. The residue was triturated with tert-butyl methyl ether (50 mL) and triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (30 mL) and the combined filtrates were concentrated. The crude solid was triturated with petroleum ether: EtOAc = 3:1 (30:10 mL), filtered, and washed with petroleum ether: EtOAc = 2:1 (20:10 mL) to give henicosyl (S)-3. -(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (1.01 g, 1.235 mmol, yield 13.91%) as a white solid. (>98% de as determined by ³¹ PNMR). ¹ H NMR (400 MHz, CDCl3) δ 7.37 (t, J = 7.7 Hz, 2H), 7.22 (d, J = 8.1 Hz, 3H), 6.67 (t, J = 8.9 Hz, 1H), 6.58 (d, J = 6.1 Hz, 2H), 4.47-4.39 (m, 1H), 4.15-4.04 (m, 2H), 3.85 (t, J = 10.4 Hz, 1H), 3.12-3.02 (m, 2H), 1.25 (s , 38H), 0.88 (t, J = 6.6 Hz, 3H). ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.60.

Step 5: 2-Butylhexyl L-phenylalaninate To a stirred solution of 2-butylhexyl (tert-butoxycarbonyl)-L-phenylalaninate (8.2 g, 20.22 mmol) in DCM (75 mL) was added TFA. (20 mL, 260 mmol) was added at 0°C. After 5 minutes, the mixture was stirred at room temperature for 2 hours. TLC showed starting material was consumed. The reaction was concentrated in vacuo to give a residue, to which water (100 mL) was added and the pH was adjusted to pH 8-9 with saturated Na ₂ CO ₃ . The resulting mixture was extracted with DCM (200 _mL x 3), washed with brine, dried over _Na2SO4 , filtered, and concentrated. The residue was purified by silica gel column (DCM:MeOH=100:0\20:1) to give 2- butylhexyl L -phenylalaninate (6.0 g, 19.64 mmol, 97% yield) as a white solid. Obtained. ¹ H NMR (400 MHz, CDCl ₃ )δ 7.31 - 7.18 (m, 5H), 4.01 - 3.99 (m, 2H), 3.72 (dt, J = 25.8, 12.9 Hz, 1H), 3.06 (dd, J = 13.5 , 5.4 Hz, 1H), 2.88 (dd, J = 13.5, 7.8 Hz, 1H), 1.60-1.51 (br, 2H), 1.28 (d, J = 17.6 Hz, 12H), 0.89 (t, J = 6.7 Hz , 6H).

Step 6: 2-Butylhexyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate. Stirring of 2-butylhexyl L-phenylalaninate (7.6 g, 24.88 mmol) To a solution of anhydrous DCM (50 mL) was added triethylamine (3.80 mL, 27.4 mmol) dropwise at −70° C. over 15 minutes. To this mixture was added a solution of phenylphosphorodichloridate (5.20 g, 24.63 mmol) in anhydrous DCM (30 mL) over 1 hour. The reaction mixture was stirred at -70°C for an additional 30 minutes, warmed to 0°C over 2 hours, and stirred at 0°C for 1 hour. To this mixture was added a solution of 2,3,4,5,6-pentafluorophenol (4.53 g, 24.63 mmol) and triethylamine (3.80 mL, 27.4 mmol) in DCM (20 mL) over 20 min. Stirred at 0°C for 4 hours. TLC showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (1 x 50 mL). The filtrate was concentrated under reduced pressure and the residue was triturated with tert-butyl methyl ether (250 mL). Triethylamine hydrochloride was then filtered off. The cake was washed with tert-butyl methyl ether (2 x 50 mL) and the combined filtrates were concentrated. The crude product was triturated with 5% EtOAc in hexanes (40 mL) and the solid was collected by filtration to give 2-butylhexyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalanyl. Nato (2.5 g, 3.98 mmol, 16.01% yield) was obtained as a white solid (>98% de as determined by ³¹ PNMR). ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.35 (t, J = 7.9 Hz, 2H), 7.25 - 7.11 (m, 6H), 7.04 (dd, J = 7.0, 2.4 Hz, 2H), 4.53 - 4.35 ( m, 1H), 3.96 (ddd, J = 36.3, 10.8, 5.7 Hz, 2H), 3.80 - 3.70 (m, 1H), 3.10 (ddd, J = 20.0, 13.7, 5.8 Hz, 2H), 1.54 (s, 1H), 1.33 - 1.11 (m, 12H), 0.88 (t, J = 6.5 Hz, 6H). ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.53.

Step 1: Dimethyl 2,2-dipentyl malonate To a stirred suspension of sodium hydride (7.57 g, 189 mmol) in DMF (100 mL) was added dimethyl malonate (10 g, 76 mmol) at 0 °C under an atmosphere of _N2 . ) was added dropwise. After 30 minutes, a solution of 1- iodopentane (37.5 g, 189 mmol) in DMF (30 mL) was added and the resulting mixture was stirred at room temperature for 16 hours. The reaction mixture was quenched with water (200 mL) and extracted twice with diethyl ether (80 mL). The combined organic layers were washed with water (100 mL x 2) and brine (100 mL x 2), dried over Na ₂ SO ₄ , filtered, and evaporated in vacuo to dimethyl 2,2-dipentyl malonate ( 27 g, 49.6 mmol, 65.5% yield) was obtained, which was used in the next step without further purification. LCMS (M+H) = 273.2, retention time (0.05% TFA): 2.66 minutes.

Step 2: Methyl 2-pentylheptanoate Stirred dimethyl 2,2-dipentyl malonate (27 g, 99 mmol), lithium chloride (8.40 g, 198 mmol) and water (1.786 mL, 99 mmol) in DMSO (150 mL). ) The mixture was heated at 180 °C for 6 h under _N2 atmosphere. LCMS showed the reaction was complete. The mixture was cooled to room temperature and diluted with _H2O (200 mL). The mixture was extracted twice with EtOAc (80 mL). The combined organic layers were washed with brine (200 mL), dried _over Na SO and concentrated to give methyl ₂ -pentylheptanoate (16 g, 39.6 mmol, 39.9% yield), which was used in the next step without purification. LCMS (M+H) = 215.3; retention time (0.05% TFA): 2.86 minutes.

Step 5: 2-Pentylheptyl-L-phenylalaninate To a stirred solution of 2- pentylheptyl (tert-butoxycarbonyl)-L-phenylalaninate (16.0 g, 36.9 mmol) in DCM (80 mL), TFA (40 mL, 519 mmol) was added at 0°C. After 5 minutes, the mixture was warmed to room temperature and stirred for 2 hours. TLC showed the reaction was complete. The reaction was concentrated to dryness, water (80 mL) was added, pH was adjusted to 8-9 with saturated Na ₂ CO ₃ and extracted with DCM (80 mL×3). The combined organic phases were washed with brine (100 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (DCM:MeOH=100:0 to 20:1) to give 2-pentylheptyl-L-phenylalaninate (8.6 g, 25.8 mmol, 69.9% yield). was obtained as a yellow oil. ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.33 - 7.27 (m, 2H), 7.22 (ddd, J = 14.6, 6.7, 4.0 Hz, 3H), 4.08 - 3.94 (m, 2H), 3.88 - 3.64 (m , 1H), 3.19 - 3.01 (m, 1H), 2.92 - 2.80 (m, 1H), 1.61 (d, J = 5.4 Hz, 1H), 1.49 (s, 2H), 1.35 - 1.20 (m, 16H), 0.89 (t, J = 6.9 Hz, 6H).

Step 1: 2-Hexyloctyl(tert-butoxycarbonyl)-L-phenylalaninate To a stirred mixture of (tert-butoxycarbonyl)-L-phenylalanine (5 g, 18.85 mmol) in DCM (100 mL) was added DMAP. (0.230 g, 1.885 mmol) and EDC (4.73 g, 24.69 mmol) were added at 0°C. After 30 minutes, 2-hexyl octan-1-ol (5.26 g, 24.53 mmol) was added at 0° C. and stirred at room temperature for 2 hours. TLC showed starting material was consumed. The reaction mixture was diluted with water (100 mL) and extracted with DCM (150 mL x 3). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ and concentrated to give 2-hexyl octyl(tert-butoxycarbonyl)-L-phenylalaninate (5.2 g, 6.76 mmol, yield 35 .9%) was obtained as a white solid , which was used in the next step without further purification. ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.26 (dq, J = 14.3, 7.1 Hz, 3H), 7.13 (d, J = 7.0 Hz, 2H), 4.97 (t, J = 11.8 Hz, 1H), 4.58 (dt, J = 16.2, 8.1 Hz, 1H), 4.26 - 3.90 (m, 2H), 3.07 (qt, J = 31.7, 15.8 Hz, 2H), 1.42 (s, 9H), 1.28 (dd, J = 22.6 , 5.5 Hz, 20H), 0.88 (t, J = 6.8 Hz, 6H).

Step 6: 2-heptylnonyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate Stirred 2-heptylnonyl L-phenylalaninate (8 g, 20.53 mmol) in anhydrous DCM (100 mL) ) Triethylamine (2.86 mL, 20.53 mmol) was added dropwise to the solution at −70° C. over 15 minutes. To this mixture was added a solution of phenylphosphonic acid dichloride (4.00 g, 20.53 mmol) in anhydrous DCM (50 mL) over 1 hour. The reaction mixture was stirred at room temperature for an additional 30 minutes, then warmed to 0° C. over 2 hours and stirred for a further 1 hour. To this mixture was added a solution of 2,3,4,5,6-pentafluorophenol (3.78 g, 20.53 mmol) and TEA (2.86 mL, 20.53 mmol) in DCM (30 mL) over 20 min. Stirred at 0°C for 16 hours. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (25 mL). The filtrate was concentrated under reduced pressure, the residue was triturated with tert-butyl methyl ether (150 mL), and the triethylamine hydrochloride was filtered off. The cake was washed with tert-butyl methyl ether (2 x 25 mL) and the combined filtrates were concentrated under reduced pressure to give a crude solid containing an equal mixture of diastereomers. The diastereomer was triturated with hexane (100 mL) and filtered to give 2-heptylnonyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate (2.5 g, 3.16 mmol, Yield 15.40%) was obtained as a white solid (>97% de as determined by ³¹ PNMR). ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.43 - 7.31 (m, 2H), 7.26 - 7.15 (m, 6H), 7.11 - 6.98 (m, 2H), 4.46 (ddd, J = 15.7, 10.1, 5.8 Hz , 1H), 4.05 - 3.85 (m, 2H), 3.78 (t, J = 11.1 Hz, 1H), 3.20 - 2.97 (m, 3H), 1.52 (d, J = 16.7 Hz, 1H), 1.33 - 1.19 ( m, 24H), 0.88 (t, J = 6.7 Hz, 6H). ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.54.

Step 2: Methyl 2-octyl decanoate Stirred dimethyl 2,2-dioctyl malonate (12 g, 33.7 mmol), lithium chloride (2.85 g, 67.3 mmol) and water (0.68 mL) in DMSO (50 mL) The mixture was stirred at reflux for 6 hours. LCMS showed the presence of the desired product. The reaction mixture was diluted with water (80 mL) and extracted with EtOAc (200 mL x 2). The combined organic phases were washed with brine, dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (100% petroleum ether) to give methyl 2-octyldecanoate (11.16 g, 33.7 mmol, 100% yield). LCMS (M+H) = 299; retention time (0.1% TFA) = 3.85 minutes.

Step 4: 2-Nonylundecyl(tert-butoxycarbonyl)-L-phenylalaninate To a stirred mixture of (tert-butoxycarbonyl)-L-phenylalanine (8.89 g, 33.5 mmol) and EDC (8.35 g, 43.5 mmol) in DCM (150 mL) was added DMAP (0.409 g, 3.35 mmol) at 0° C. After 30 min, 2- nonylundecan -1-ol (10 g, 33.5 mmol) was added and the resulting reaction mixture was stirred at 25° C. for 16 h. TLC showed the reaction was complete. The reaction mixture was diluted with water (80 mL) and extracted with DCM (100 mL×2). The combined organic phase was washed with brine, dried over Na ₂ SO ₄ and concentrated. The residue was purified by silica gel chromatography (petroleum ether: EtOAc = 10:1) to give 2-nonylundecyl (tert-butoxycarbonyl)-L-phenylalaninate (16 g, 29.3 mmol, 88% yield) as a yellow oil. ^1H NMR (400 MHz, _CDCl3 ) δ 7.28-7.22 (m, 3H), 7.13 (d, J = 1.6 Hz, 2H), 4.98 (t, J = 4.0 Hz, 1H), 4.57 (m, 1H), 4.00 - 3.96 (m, 2H), 3.01 (qt, J = 31.7, 15.8 Hz, 2H), 1.41 (s, 9H), 1.26 (dd, J = 22.6, 5.5 Hz, 32H), 0.88 (t, J = 6.8 Hz, 6H).

Step 6: 2-Nonylundecyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate Stirred 2-nonylundecyl L-phenylalaninate (8 g, 17.95 mmol) in anhydrous DCM (100 mL) ) Triethylamine (2.502 mL, 17.95 mmol) was added dropwise to the solution at −70° C. over 15 minutes. To this mixture was added a solution of phenylphosphonic acid dichloride (3.50 g, 17.95 mmol) in anhydrous DCM (50 mL) at −70° C. over 1 hour. The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for a further 1 hour. To this mixture was added a solution of 2,3,4,5,6-pentafluorophenol (3.30 g, 17.95 mmol) and TEA (2.502 mL, 17.95 mmol) in DCM (30 mL) over 20 min. Stirred at 0°C for 16 hours. LCMS showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (25 mL). The filtrate was concentrated under reduced pressure and the residue was triturated with tert-butyl methyl ether (150 mL). Triethylamine hydrochloride was then filtered off. The cake was washed with tert-butyl methyl ether (2 x 25 mL) and the combined filtrates were concentrated under reduced pressure to give a crude solid containing an equal mixture of diastereomers. The mixture was triturated with hexane (15 mL) and filtered to give 2-nonylundecyl ((S)-(perfluorophenoxy)(phenoxy)phosphoryl)-L-phenylalaninate (1.5 g, 1.856 mmol, yield 10.34%) was obtained as a white solid (>98% de as determined by ³¹ PNMR). ¹ H NMR (400 MHz, CDCl ₃ ) δ 7.35 (t, J = 7.8 Hz, 2H), 7.26 - 7.15 (m, 6H), 7.03 (dd, J = 13.7, 9.1 Hz, 2H), 4.45 (ddd, J = 15.6, 10.1, 5.8 Hz, 1H), 4.09 - 3.89 (m, 2H), 3.86 - 3.75 (m, 1H), 3.22 - 2.99 (m, 2H), 1.54 (s, 1H), 1.27 (dd, J = 27.8, 9.6 Hz, 32H), 0.88 (t, J = 6.7 Hz, 6H). ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.53.

Example 67: 2-Butylhexyl (S)-2-(((S)-(((2R,3S,5R)-5-(6-amino-2-fluoro-9H-purin-9-yl)- 2-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)amino)-3-(3,5-difluorophenyl)propanoate

Step 1: 2-Butylhexyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl) )-amino)-3-(3,5-difluorophenyl)propanoic acid (4 g, 13.28 mmol) in DCM (60 mL) with DMAP (0.162 g, 1.328 mmol) and EDC (3.31 g, 17.26 mmol). ) was added at 0°C. The resulting reaction mixture was stirred at the same temperature for 30 minutes, then 2-butylhexan-1-ol (2.52 g, 15.93 mmol) was added. The resulting reaction mixture was stirred at 25°C for 16 hours. LCMS showed the reaction was complete. The reaction was diluted with water (50 mL) and extracted with DCM (100 mL x 2). The combined organic layers were washed with brine (40 mL), dried over Na ₂ SO ₄ , filtered, concentrated to give 2-butylhexyl (S)-2-((tert-butoxycarbonyl)amino)-3- (3,5- difluorophenyl )propanoate (4.6 g, 10.42 mmol, 78% yield) was obtained as a white solid, which was used in the next step without further purification. LCMS: (M+Na) = 464.0; retention time (0.1% TFA) = 2.59 minutes.

Step 2: 2-Butylhexyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate To a stirred solution of 2-butylhexyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl )propanoate (4.6 g, 10.42 mmol) in DCM (60 mL) was added TFA (15 mL, 195 mmol) dropwise at 0 °C. The resulting reaction mixture was stirred at 25 °C for 16 h. LCMS showed the reaction was complete. The reaction mixture was concentrated and the residue was neutralized with NaHCO ₃ (40 mL) and extracted with DCM (3 x 80 mL). The combined organic layers were washed with brine (40 mL), dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate=2/1) to give 2-butylhexyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (3.3 g, 9.66 mmol, 93% yield) as a pale yellow solid. LCMS (M+H)=342.1; retention time (0.1% TFA)=1.76 min. Purity: 100% (254 nm).

Step 1: 2-heptylnonyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate To a stirred solution of (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoic acid (10 g, 33.2 mmol) in DCM (120 mL) was added DMAP (0.405 g, 3.32 mmol) and EDC (8.27 g, 43.1 mmol) at 0° C. and stirred at the same temperature for 30 min. Then, to this mixture was added a solution of 2-heptylnonan-1-ol (9.66 g, 39.8 mmol) in DCM (10 mL) and stirred at 25° C. for 16 h. LCMS showed the reaction was complete. The reaction mixture was diluted with water (50 mL) and extracted with DCM (200 mL×3). The combined organic layers were washed with brine (50 mL), dried over Na ₂ SO ₄ , filtered and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate=20/1) to give 2-heptylnonyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl) propanoate (12.5 g, 22.13 mmol, 66.7% yield) as a white solid. LCMS: (M+Na)=548.2; retention time (0.05% TFA)=3.83 min; purity: 93.08% (214 nm).

Step 2: 2-heptylnonyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirred 2-heptylnonyl (S)-2-((tert-butoxycarbonyl)amino)-3- To a solution of (3,5- difluorophenyl )propanoate (12.5 g, 23.78 mmol) in DCM (90 mL) was added TFA (20 mL, 260 mmol) dropwise at 0° C. and stirred at 25° C. for 4 hours. LCMS showed the reaction was complete. The reaction mixture was concentrated and the residue was neutralized with NaHCO ₃ (50 mL). The mixture was partitioned between water (50 mL) and DCM (300 mL). The aqueous layer was extracted with DCM (2 x 200 mL). The combined organic layers were washed with brine (60 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate = 2/1) to give 2-heptylnonyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (7 g, 15.98 mmol). , yield 67.2%) as a pale yellow oil. LCMS (M+H) = 426.4; Retention time (0.05% TFA) = 2.12 min; Purity: 97.15% (214 nm).

Step 1: 2-Octyldecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl) ) Amino)-3-(3,5-difluorophenyl)propanoic acid (10 g, 33.2 mmol) in DCM (120 mL) with DMAP (0.405 g, 3.32 mmol) and EDC (8.27 g, 43.1 mmol) ) was added at 0°C and stirred at the same temperature for 30 minutes. A solution of 2-octyldecan-1-ol (10.77 g, 39.8 mmol) in DCM (10 mL) was then added to the mixture and stirred at 25° C. for 16 h. LCMS showed the reaction was complete. The reaction mixture was diluted with water (50 mL) and extracted with DCM (200 mL x 2). The combined organic layers were washed with brine (50 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate = 20/1) to give 2-octyldecyl(S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluoro Phenyl )propanoate (13.5 g, 20.11 mmol, 60.6% yield) was obtained as a white solid. LCMS: (M+Na) = 576.2; retention time (0.1% TFA) = 4.81 min; purity: 82.50% (214 nm).

Step 2: 2-Octyldecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirred 2-octyldecyl (S)-2-((tert-butoxycarbonyl)amino)- To a solution of 3-(3,5-difluorophenyl) propanoate (13.5 g, 24.38 mmol) in DCM (100 mL) was added TFA (20 mL, 260 mmol) dropwise at 0° C. and stirred at 25° C. for 16 hours. LCMS showed the reaction was complete. The reaction was concentrated and the residue was neutralized with NaHCO ₃ (50 mL) and extracted with DCM (3×200 mL). The combined organic layers were washed with brine (60 mL), dried over Na ₂ SO ₄ , filtered, and concentrated. The residue was purified by silica gel chromatography (petroleum ether/ethyl acetate = 2/1) to give 2-octyldecyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate (7.1 g, 15.65 mmol, yield 64.2%) was obtained as a pale yellow oil. LCMS (M+H) = 454.3; retention time (0.05% TFA) = 2.35 min; purity: 100% (254 nm).

Step 3: 2-Octyldecyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate Stirred 2-octyldecyl To a solution of (S)-2-amino-3-(3,5-difluorophenyl)propanoate (7.1 g, 15.65 mmol) in DCM (100 mL) was added triethylamine (2.393 mL, 17.22 mmol) at -70 °C. It was dripped. To this mixture was added dropwise a solution of phenylphosphorodichloridate (3.27 g, 15.49 mmol) in anhydrous DCM (20 mL). The reaction mixture was stirred at this temperature for a further 30 minutes, then warmed to 0° C. over 2 hours and stirred for 1 hour. To this mixture was added dropwise a solution of 2,3,4,5,6-pentafluorophenol (2.88 g, 15.65 mmol) and triethylamine (2.393 mL, 17.22 mmol) in DCM (20 mL). The crude mixture was stirred at 0°C for 16 hours. LCMS showed the reaction was complete. The reaction mixture was concentrated under reduced pressure, the residue was triturated with tert-butyl methyl ether (200 mL), and triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (2 x 30 mL) and the combined filtrates were concentrated under reduced pressure. The mixture was triturated with hexane (50 mL) and the solid was collected by filtration. The filtrate was concentrated, the residue was triturated with hexane (25 mL), and the solid was collected by filtration. Repeat this procedure twice to obtain 2-octyldecyl (S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (1.5 g). , 1.570 mmol, yield 10.03%) as a white solid (>98% de as determined by ³¹ PNMR). LCMS (M+H) = 776.0; Retention time (0.1% TFA) = 4.75 minutes. ³¹ PNMR (CDCl ₃ , 162 MHz) δ -1.56.

Step 1: 2-Pentylheptyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl) ) Amino)-3-(3,5-difluorophenyl)propanoic acid (8.71 g, 28.9 mmol) in DCM (50 mL) was added with EDC (7.22 g, 37.6 mmol) and DMAP (0.353 g). , 2.89 mmol) was added at 0°C. After 30 minutes, a solution of 2-pentylheptan-1-ol (7.00 g, 37.6 mmol) in DCM (20 mL) was added at 0° C. and the reaction was stirred at 15° C. for 16 hours. LCMS showed product detected. The reaction mixture was diluted with water (30 mL) and extracted with DCM (25 mL x 2). The combined organic phases were washed with brine, dried _over Na SO and concentrated to yield 2 _- pentylbeptyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl). ) Propanoate (11.2 g, 7.99 mmol, 27.6% yield) was obtained as a yellow oil, which was used in the next step without further purification. LCMS (2M+Na) = 961.2; retention time (10% TFA) = 2.854 minutes.

Step 1: 2-Nonylundecyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate To a stirred solution of (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoic acid (6 g, 19.91 mmol) in DCM (60 mL) was added N,N-dimethylpyridin-4-amine (0.243 g, 1.991 mmol) and 3-(((ethylimino)methylene)amino)-N,N-dimethylpropan-1-amine hydrochloride (4.97 g, 25.9 mmol) at 0° C. After 30 min, a solution of 2-nonylundecan-1-ol (7.73 g, 25.9 mmol) in DCM (15 mL) was added dropwise to the above solution at 0° C. and stirred at 15° C. overnight. The reaction mixture was then diluted with water (30 mL) and partitioned. The aqueous phase was extracted with DCM (35 mL x 2) and the combined organic phases were washed with brine (20 _mL ), dried over _Na2SO4 , filtered and concentrated in vacuo to afford 2-nonylundecyl(S)-2-((tert-butoxycarbonyl)amino)-3-(3,5- difluorophenyl )propanoate (14.06 g, 24.17 mmol, 121% yield) as a yellow oil, which was used in the next step without purification.

Step 1: 2-Hexyloctyl (S)-2-((tert-butoxycarbonyl)amino)-3-(3,5-difluorophenyl)propanoate Stirred (S)-2-((tert-butoxycarbonyl) )-amino)-3-(3,5-difluorophenyl)propanoic acid (5 g, 16.60 mmol), DMAP (0.203 g, 1.660 mol) and 2-hexyloctan-1-ol (4.63 g, 21. 60 mmol) was added to a solution of EDC (4.14 g, 21.61 mmol) in DCM (20 mL) at 0°C and stirred at 0°C for 2 hours. LCMS showed the presence of the desired product. The reaction mixture was diluted with water (50 mL) and the organic phase was washed with brine, dried over Na ₂ SO ₄ and concentrated to yield 2-hexioctyl(S)-2-((tert-butoxycarbonyl)amino)- 3-(3,5- difluorophenyl )propanoate (8 g, 15.33 mmol, 92% yield) was obtained as an oil. LCMS (M+Na) = 520.2; retention time (0.1% TFA) = 3.42 minutes.

Step 2: 2-Hexyloctyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate Stirred 2-hexyoctyl (S)-2-((tert-butoxycarbonyl)amino)-3 To a solution of -(3,5- difluorophenyl )propanoate (8 g, 16.07 mmol) in DCM (30 mL) was added TFA (12.38 mL, 161 mmol) and the resulting mixture was stirred at 5 °C for 2.5 h. did. LCMS showed the reaction was complete. The pH of the reaction mixture was adjusted to ~8 with 1N NaOH, diluted with water (30 mL), stirred vigorously for 20 min, the organic phase was separated, washed with saturated NaCl (50 mL) and dried ( _{Na2SO4 )} . ), concentrated. The crude product was purified by silica gel chromatography (120 g, Santai, EtOAc:petroleum ether = 1:50) to give 2-hexyloctyl (S)-2-amino-3-(3,5-difluorophenyl)propanoate ( 4.1 g, 7.08 mmol, yield 44.1%) was obtained as an oil. LCMS (M+H) = 398.4; retention time (0.1% TFA) = 1.92 minutes.

Step 3: 2-Hexyloctyl(S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate To a stirred solution of 2-hexyloctyl(S)-2-amino-3-(3,5-difluorophenyl)propanoate (4.1 g, 10.31 mmol) in DCM (50 mL) was added ET ₃ N (1.509 mL, 10.83 mmol) dropwise over 15 min at −70° C. To this mixture was added a solution of phenyl phosphorodichloridate (2.154 g, 10.21 mmol) in anhydrous DCM (35 mL) over 1 h. The reaction mixture was stirred at this temperature for an additional 30 min, then allowed to warm to 0° C. over 2 h and stirred for 2 h. To this mixture was added a solution of ET ₃ N (1.581 mL, 11.34 mmol) and 2,3,4,5,6-pentafluorophenol (1.879 g, 10.21 mmol) in DCM (30 mL) over 20 min and stirred at 0° C. for 4 h. LCMS showed the reaction was complete. The white solid (triethylamine hydrochloride) was filtered off and washed with DCM (1×25 mL). The filtrate was concentrated under reduced pressure. The residue was triturated with tert-butyl methyl ether (50 mL) and the triethylamine hydrochloride was removed by filtration. The cake was washed with tert-butyl methyl ether (25 mL) and the combined filtrate was concentrated under reduced pressure to give 2.0 g. The crude solid was triturated with petroleum ether (10 mL), filtered and washed with petroleum ether (5 mL) to give 2-hexyloctyl(S)-3-(3,5-difluorophenyl)-2-(((S)-(perfluorophenoxy)(phenoxy)phosphoryl)amino)propanoate (800 mg, 1.112 mmol, 10.78% yield) as a white solid (>95% de as determined by ³¹ PNMR) LCMS (M+H)=720.2, retention time (0.1% TFA)=3.45 min. ³¹ PNMR (CDCl ₃ , 162 MHz) δ-1.56.