TWI398429B - Method and precursor for production of no-carrier-added n-(4-[18f]fluorobutyl)-ethacrynic amide - Google Patents

Description

Fluorine-18FBuEA precursor and preparation method thereof

The present invention relates to a nuclear medicine imaging illuminant tracer, especially a carrier-free fluorine-18-labeled ethanoic acid N- (4-[ ¹⁸ F]fluorobutyl)-Ethacrynic amide ([ ¹⁸ F]FBuEA). And its high performance liquid chromatography (HPLC) non-radioactive standard preparation method.

Currently used to detect radiopharmaceutical detection instruments, such as magnetic contrast contrast contrast agents must use magnetic magnetic susceptibility atoms for magnetic markers, the atomic metal is not suitable for small molecule drugs, and whether it is ultrasound or magnetic resonance imaging Contrast contrast agents, the magnitude of the signal is far less than that of gamma rays, and cannot be detected with very small amounts of drugs. The technique of positron emission tomography or single photon emission tomography makes it feasible to use biochemical analysis of biochemical processes. The principle of operation is through some radioactive tracers, all of which are radioactive nucleus. Compounds, single photon emission tomography and positron emission tomography are all nuclear medical imaging. For the selection of radioactive nucleus, it is necessary to consider "the combination of nuclear and detection instruments" and "biocompatibility of nuclear species". If the nucleus emits gamma rays, SPECT can be used; if the nucleus emits positrons, the positrons and electrons will destroy the gamma rays with the opposite direction and energy of 511 keV, which can be detected by PET. Most of the biocompatible nuclear species are mainly positron emission, for example, carbon-11, nitrogen-13, oxygen-15, fluorine-18, bromine-75, bromine-76, bromine-80g, iodine- 124. The reason why fluorine is biocompatible is because the van der Waals radius of fluorine is similar to that of hydrogen, so it can replace hydrogen. Ethacrynic acid has been found to have anticancer potential, and its target protein is glutathione S-transferase P1-1 (GSTP1-1), which is widely found in many cancer cells and has Studies have confirmed that it is related to the drug resistance of cancer chemotherapy. Recently, some research groups have found that if ethene-modified ethanyl acid forms itanide, it can enhance the ability to kill cancer cells. However, the stability of ester bonds is not as good. The indole bond, so the inventors used a guanamine bond instead of an ester bond, and it is expected to produce clinically practical value. The chemical structural formula of fluorine-18 butyl ethanilide (2). as follows:

The object of the present invention is to provide an unsupported fluorine-18-labeled hexanone acid N- (4-[ ¹⁸ F]fluorobutyl)-Ethacrynic amide (hereinafter [ ¹⁸ F]FBuEA) precursor and its HPLC non-radioactive standard Preparation. The chemical structure formula (1) of [ ¹⁸ F]FBuEA precursor is as follows:

Where the structure is used to synthesize a [ ¹⁸ F]FBuEA precursor, R ¹ represents a protecting group of a guanamine functional group, R ² represents a leaving group; R ¹ represents a carboxyl group, and R ² represents a p- group; Tosyloxy, methane sulfonyloxy or trifluoromethanesulfonyloxy or bromo (Br).

Where the structure is used in the synthesis of HPLC non-radioactive standards, R ¹ represents a protecting group of a guanamine functional group and hydrogen, and R ² represents fluorine. The injection of N- (4-[ ¹⁸ F]fluorobutyl)-Ethacrynic amide can be used for nuclear medicine imaging of tumor diagnosis and therapeutic effect tracking.

Fluorine-18-labeled precursor Toluene-4-sulfonic acid 4-(tert-butoxycarbonyl-Ethacrynamino)-butyl ester (9) and its HPLC non-radioactive standard {2-[2,3-Dichloro-4-(2-methylene) -butyryl)-phenoxy]-acetyl}-(4-fluoro-butyl)-carb amic acid tert-butyl ester (10) and 2-[2,3-Dichloro-4-(2-methylene-butyryl)-phenoxy] A preferred embodiment of the separate process of -N-(4-fluoro-butyl)-acetamide (11) is as follows:

(a) Synthesis steps of [2,3-Dichloro-4-(2-methylene-butyryl)-phenoxy]-acetic acid methyl ester (methyl Ethacrynate) (4):

(1) A light yellow powder of 1.16 g (1.5 eq, 9.90 mmol) of nitrosomethylurea was added, and added to a round bottom flask containing 80 mL of Et ₂ O, and stored under nitrogen, and transferred to an ice bath.

(2) Take 1 g of KOH (2.7 eq, 17.82 mmol), dissolve it with 16 mL of secondary water to obtain an aqueous solution of potassium hydroxide, and inject the KOH aqueous solution into a round bottom bottle containing nitrosomethylurea in an ice bath, at which time nitrosomethylurea will dissolve to produce diazomethane. (CH ₂ N ₂ , bp ~ -23 ° C) yellow gas (still need to be used quickly to avoid gas dissipation), layered with an ice bath separatory funnel and collect the organic layer, and add KOH under ice bath conditions Do not dissolve to remove water.

(3) Starting material to be reacted ( 3 ) 2 g of diuretic acid (1 eq, 6.60 mmol) was dissolved in 20 mL of EtOAc, and the previously prepared diazomethane (CH ₂ N ₂ , bp ~ -23 ° C) diethyl ether solution was injected. Until the yellow diazomethane is no longer consumed, it will stop when it is light yellow (TLC is developed with EtOAc/n-Hexane 1/4, showing both disappearance of the starting material and product formation).

(4) Stop the excess diazomethane with a small amount of acetic acid, clarify the reaction solution, remove excess reaction solvent at 40 ° C with a rotary vacuum concentrator, and finally use EtOAc/n-hexane 3/17 as the ruthenium tube column. After separation, the product ( 4 ) of a translucent soft solid was obtained in an amount of about 1.9 g (yield: -90%).

(b) 2-[2,3-Dichloro-4-(2-methylene-butyryl)-phenoxy]-N-(4-hydroxy-butyl)-ac Synthetic steps of etamide (5):

(1) ₍₂ and water removal by distillation under reduced pressure CaH2) was dissolved starting material (4) (1.1g, 1eq, 2.94mmol) and place under nitrogen systems 40mL dry DMF.

(2) Add about 5 mL of triethylamine (Et ₃ N, remove water with KOH and distill off ~10 eq, 29.4 mmol, d 0.71), then add 4-amino-1-butanol about 1.5 mL (~5.5 eq, 162 mmol) , d 0.96), placed on a magnet stirring and heated to 55-60 ° C in an oil bath. A drying tube with a blue silicone rubber is placed over the round bottom reaction bottle to open the system to allow methanol to escape, but to prevent moisture from entering.

(3) After the reaction was continued for about 8 hours, TLC was developed with acetone/n-hexane 1/3, and a high vacuum was applied to remove the solvent. It was observed that the starting material ( 4 ) disappeared and the product formed (ninhydride colorless, R _f ~0.23).

(4) The oil is pumped at 55 ° C under reduced pressure to remove most of the reaction solvent, and finally separated by acetone / n-hexane 1/3 → 3 / 7 gradient ruthenium column chromatography, white The foamy product ( 5 ) was about 255 mg (yield: ~20%).

(c) Synthesis step of N-[4-(tert-Butyl-dimethyl-silanyloxy)-butyl]-2-[2,3-dichloro-4-(2-methylene-butyryl)-phenoxy]-acetamide (6) :

(1) Take 220 mg of starting material ( 5 ) (1 eq, 0.45 mmol) dissolved in toluene and azeotropically removed with high vacuum, then dissolved with 11 mL of CH ₂ Cl ₂ (from distillation system), and added to the flask. On the nitrogen system.

(2) TBDMSCl (3.6 eq, 1.62 mmol,), pyridine (0.5 mL from the distillation system) was dissolved in another two-necked flask with 11 mL of CH ₂ Cl ₂ (from the distillation system), and taken out with a syringe. The starting material (5) and a nitrogen-filled double-necked flask.

(3) Finally, DMAP (dimethylaminopyridine, 1.6 eq, 0.73 mmol, 90 mg) was dissolved by heating in toluene and azeotroped with high vacuum three times to remove water, stirred with a magnet and kept at room temperature for about 8 to 9 hours, after TLC Starting with acetone/n-hexane 1, it was observed that the starting material (5) disappeared and the product (6) formed.

(4) After the reaction mixture was placed in a single-neck round bottom bottle, the excess reaction solvent was removed at 40 ° C using a rotary vacuum concentrator, and finally separated by EtOAc/n-hexane 3/7 as a silica gel column chromatography to obtain an oil. The product (6) was about 200 mg (yield: ~70%).

(d) [4-(tert-Butyl-dimethyl-silanyloxy)-butyl]-{2-[2,3-dichloro-4-(2-methylene-butyryl)-phenoxy]-acetyl}-carbamic acid tert-butyl Synthetic steps of ester(7):

(1) Take 200 mg of starting material ( 6 ) (1 eq, 0.41 mmol) first dissolved in toluene and azeotropically removed with high vacuum, then dissolved in 10 mL of CH ₂ Cl ₂ (from distillation system), and added to the flask. Pass the nitrogen system.

(2) Boc ₂ O (2.1 eq, 0.2 mL, 0.87 mmol, d0.95, mp 23 ° C) and Et ₃ N (1.4 eq, 0.08 mL, d 0.73 from a vacuum distillation system) were taken out with a syringe and added In a two-necked flask containing the starting material (6) and passing nitrogen, DMAP (dimethylaminopyridine, 1.6 eq, 80 mg, 0.66 mmol) was finally placed and dissolved in toluene and azeotroped with high vacuum three times to remove water, and stirred with a magnet. After the reaction was continued for about 12 hours at room temperature, TLC was developed with EtOAc/n-hexane 3/7, and it was observed that starting material ( 6 ) disappeared and product ( 7) was formed.

(3) After the reaction mixture was placed in a single-necked round bottom flask, the excess reaction solvent was removed at 40 ° C using a rotary vacuum concentrator, and finally separated by EtOAc/n-hexane 1/9 as a silica gel column chromatography to obtain an oil. The product (7) was about 185 mg (yield: ~76%).

(e) Synthesis steps of {2-[2,3-Dichloro-4-(2-methylene-butyryl)-phenoxy]-acetyl}-(4-hydroxy-butyl)-carbamic acid tert-butyl ester (8):

(1) Approximately 200 mg (1 eq, 0.34 mmol) of the starting material (7) was dissolved in about 10 mL of THF of a distillation system and placed in a magnet.

(2) 1M TBAF/THF (5% water) was taken to about 0.34mL (~1.0eq) and acetic acid (AcOH, 1.0eq, 0.02mL, d 1.05, 0.33mmol) was first mixed with 10mL THF, and then added In the round bottom flask of the starting material, the reaction was carried out at room temperature for one night (16 h) with a stirring of a magnet, and TLC was developed with EtOAc/n-hexane 3/7 and 1 to observe that the starting material disappeared and the product ( 8 ) was formed ( 5 <R _f < 6,7 ).

(3) The excess reaction solvent was removed by a rotary vacuum concentrator at 40 ° C, and finally separated by EtOAc/n-hexane 3/7 as a silica gel column chromatography to give an oily product (8) about 120 mg (yield: ~ 75%).

(f) Toluene-4-sulfonic acid 4-(tert-butoxycarbonyl-{2-[2,3-dichloro-4-(2-methylene-butyryl)-phenoxy]-acetyl}-amino)-butyl ester(9) (precursor) synthesis steps:

(1) Starting material ( 8 ) 30 mg (1 eq, 0.063 mmol) was first dissolved in toluene and azeotroped with high vacuum. After adding the magnet, it was placed in a nitrogen system with a nitrogen balloon, using dichloromethane (from the distillation system). 2mL dissolved.

(2) The reaction bottom flask containing the starting material was placed in an ice bath (0-5 ° C), then TsCl (1.25 eq, 15 mg, 0.079 mmol) dissolved in dichloromethane was added from EtOAc/n-hexane Recrystallized co-crystals) and injected with pyridine 0.08 mL (from distillation system).

(3) After the reaction was stirred for half an hour in an ice bath, the reaction flask containing the nitrogen balloon was placed in a refrigerator (4 ° C) for one night, and some products were still observed by TLC with EtOAc/n-hexane=1 ( 9). ), while the starting material ( 8 ) was reduced but not completely disappeared (addition of some TsCl (0.5 eq) or another day after the improvement, there was some improvement but no significant improvement).

(4) After concentrating under reduced pressure, the crude product was separated by EtOAc/n-hexane 1/4 as a silica gel column chromatography to give a product (9) of about 5-6 mg (yield: ~20). %), and about 10 mg (yield: ~33%) of the starting material ( 8 ) was recovered.

(g) {2-[2,3-Dichloro-4-(2-methy1ene-butyryl)-phenoxy]-acetyl}-(4-fluoro-butyl)-carbamic acid tert-butyl ester (10): (HPLC non- Radioactive standard)

(1) Take the starting material ( 8 ) 50 mg (1 eq, 0.106 mmol), azeotropically remove water with toluene, dissolve with about 5 mL of dichloromethane (from distillation system), transfer to a magnetic flask containing a magnetic flask and place in a nitrogen system. under.

(2) Next, the flask containing the starting material was placed in a -78 ° C low temperature reaction tank, and DAST (diethylaminosulfur trifluoride) was added slowly (~1.5 eq, 20 uL, 0.15 mmol, d 1.22, bp 30- 32 ° C), the magnet was stirred at -78 ° C for 30 min -1 h, then the flask was slowly returned to room temperature, TLC was developed with EtOAc / n-hexane 2 / 3 & 3 / 7 to observe the starting material ( 8 ) disappears and product ( 10 ) is formed.

(3) There is still some unknown formation in the TLC origin (R _f =0). Was added 5mL ice-cold saturated NaHCO _{3 (aq),} extracted three times with dichloromethane (3 X 10 mL), the organic layer was collected and washed with Na ₂ SO _{4 (s)} in addition to water, gravity filtered to remove Na ₂ SO _{4 (s),} and concentrated under reduced pressure with skipping dichloromethane, and finally with EtOAc / n-hexane 1/4 as silica gel column chromatography, the product can be obtained as a clear oil (10) about 22mg (yield: ~ 45%).

(h) 2-[2,3-Dichloro-4-(2-methylene-butyryl)-phenoxy]-N-(4-fluoro-butyl)-acetamide (11): (HPLC non-radioactive standard)

(1) 15 mg of the starting material ( 10 ) was dissolved in dichloromethane, and a magnet and 0.25 mL of TFA were added. After stirring at room temperature for half an hour, TLC disappeared with EtOAc/n-hexane 1 ( 10 ). And product ( 11 ) is produced.

(2) After concentrating at 40 ° C under rotary reduced pressure, and finally separating with EtOAc/n-hexane 3/7 as a silica gel column chromatography to give white product ( 11 ) about 8 mg (yield: ~70%, mp 94-96 ° C).

Claims (2)

A process for preparing unsupported (Non-carrier) for fluorine- 18 labeled ethacrynic acid ^{(N - (4- [18 F} ] fluorobutyl) -Ethacrynic amide) precursors of which chemical structure is as follows: The structure can be made separately, with a carrier-free fluorine-18-labeled ethienoic acid-fluoro-labeled precursor and a high performance liquid chromatography (HPLC) non-radioactive standard, wherein the portion for the precursor: R ¹ : represents acyl protective group of the amine functional group, a tert-butoxycarbonyl ^{(tert -butoxycarbonyl group), R 2} : represents a leaving group, p is a sulfonylurea oxygen (p -tosyloxy), acyl oxygen methanesulfonamide (methane sulfonyloxy) group Or a trifluoromethanesulfonyloxy group or a bromine (Br) group. A method for preparing a precursor of a carrier-free fluorine- 18-labeled ethanoic acid ( N- (4-[ ¹⁸ F]fluorobutyl)-Ethacrynic amide), comprising the following steps: (1) taking {2-[ 2,3-Dichloro-4-(2-methylene-butenyl)-phenoxy]-ethenyl}-(4-hydroxy-butyl)-carbamic acid tert-butyl butyl ester ({2-[2 , 3-Dichloro-4-(2-methylene-butyryl)-phenoxy]-acetyl}-(4-hydroxy-butyl)-carbamic acid tert-butyl ester) as a starting material, the chemical structural formula is as follows: Dissolving the starting material with toluene and azeotroping with high vacuum, adding the magnet, placing it in a nitrogen system with a nitrogen balloon, dissolving the mixture with methylene chloride from the distillation system, and (2) containing the starting material. The reaction round bottom bottle was placed under ice bath (about 0-5 ° C), and then 4-toluenesulfonium chloride (TsCl, tosyl chloride), which was obtained from the step (1), was dissolved in dichloromethane. EtOAc) / n-hexane (recrystallized co-crystals of n-hexane), and pyridine (pyridine) is added in a distillation system; (3) the mixture obtained in the step (2) is stirred under ice bath conditions and reacted for about half. After the hour, the reaction flask containing the nitrogen balloon was placed in a refrigerator (about 4 ° C) for one night, and then subjected to thin layer chromatography (TLC) at a ratio of ethyl acetate / n-hexane = 1; and (4) the step (3) The obtained crude product is concentrated under reduced pressure, and then separated into a column of ethyl acetate/n-hexane = 1/4 as a silica gel column chromatography to obtain a transparent oil precursor, namely toluene-4- Sulfonic acid 4-(tertiary butoxycarbonyl-{2-[2,3-dichloro-4-(2-methylene-butanyl)-phenoxy]-ethenyl}-amino)-butyl ester (Toluene-4-sulfonic aci d 4-(tert-butoxycarbonyl-{2-[2,3-dichloro-4-(2-methylene-butyryl)-phenoxy]-acetyl}-amino)-butyl ester), its chemical structural formula is as follows: And recover the starting material {2-[2,3-dichloro-4-(2-methylene-butenyl)-phenoxy]-ethenyl}-(4-hydroxy-butyl)-carbamic acid Tertiary butyl ester.