orlistat impurity F, preparation method and application thereof
The invention belongs to the field of pharmaceutical chemistry, and particularly relates to N-formyl-L-leucine- (3S,4R,6R) -3-hexyl-2-oxo-6-deca alkyl tetrahydro-2H-pyranyl ester (orlistat impurity F) and a preparation method and application thereof.
The obesity-reducing drug Orlistat (Orlistat) developed by Roche of Switzerland is specific gastric lipase and pancreatic lipase inhibitors which have non-systemic effect, long-acting effect and strong effect, and forms an inactive intermediate with gastrointestinal lipase to irreversibly inhibit the enzyme, thereby weakening the digestion and absorption of fat, keeping the intestinal tract in an oil phase state, isolating cholesterol and excreting through feces, and achieving the purpose of reducing the weight of a patient.
Orlistat was first approved by the FDA in the united states for marketing over the counter weight loss drug for the treatment of obesity at 23/4 1999 under the trade name cenicrobial (xenoical), which has been marketed in over 100 countries worldwide, and because of its high safety, it is widely available to patients since the time of marketing, and has a high market prospect.
In the orlistat preparation process, certain process impurities are generated in the drug, and the existence of the impurities can greatly influence the medication safety, so that the establishment of a corresponding drug quality analysis method through directional preparation of target impurities has important significance in effectively controlling the quality of bulk drugs and related preparations.
Disclosure of Invention
The invention provides an orlistat impurity F, the chemical name of which is N-formyl-L-leucine- (3S,4R,6R) -3-hexyl-2-oxo-6-deca alkyl tetrahydro-2H-pyranyl ester, the name of English is N-formamyl-L-leucine- (3S,4R,6R) -3-hexyl-2-oxygen-6-undecyl tetrahydrogen-2H-pyranyl, and the specific formula is shown as the following formula (I):
in another aspect , the present invention provides a method for preparing orlistat impurity F, comprising the steps of:
1) the orlistat key intermediate β -lactone (chemical name is (3S,4S) -3-hexyl-4- [2- (R) -hydroxy-tridecyl ] -oxetan-2-one) shown in formula (II) is stirred and dissolved in alkali, water and organic solvent, and then heated for ring-opening reaction to obtain a product (formula (III) (chemical name is (2S,3S,5R) -2-hexyl-3, 5-dihydro-2H-hexadecanoic acid);
2) performing cyclization reaction on the product formula (III) obtained in the step 1) under the catalysis of an acidic substance to obtain a product formula (IV);
3) reacting the product of formula (IV) (chemical name is (3S,4S,6R) -3-hexyl-2-oxo-6-deca alkyltetrahydro-2H-pyranyl ester) obtained in step 2) with N-formyl-L leucine (V) in triphenylphosphine (PPh)3) Carrying out Mitsunobu reaction with diisopropyl azodicarboxylate (DIAD) to obtain orlistat impurity F shown in the formula (I);
in embodiments of the invention, the base in step 1) is or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate and potassium carbonate, preferably or a mixture of two of sodium hydroxide and sodium carbonate, the organic solvent used in the ring opening reaction is or more of tetrahydrofuran, toluene, methanol, ethanol and 1, 4-dioxane, preferably or a mixture of two of tetrahydrofuran and ethanol, the reaction molar ratio of the key orlistat intermediate β -lactone of formula (II) to the base is 1 (1-10), preferably 1 (2-8), the temperature of the heating and ring opening reaction is controlled at 10-100 ℃, preferably 30-80 ℃, the reaction time of the ring opening reaction is 1-10 hours, preferably 2-8 hours, the mass ratio of the base to the water is 1 (1-5), preferably 1 (2-4), the mass ratio of the key orlistat intermediate β -lactone of formula (II) to the organic solvent is 1-15, preferably 1-1.
In embodiments of the invention, the acidic substance in step 2) is or more of sulfuric acid, hydrochloric acid, acetic acid and p-toluenesulfonic acid, preferably or a mixture of two of hydrochloric acid and p-toluenesulfonic acid, the cyclization reaction is performed in an organic solvent 2, the organic solvent 2 is or more of tetrahydrofuran, toluene and dichloromethane, preferably or a mixture of two of toluene and dichloromethane, the reaction molar ratio of the product formula (III) to the acidic substance is 1 (1-2.5), preferably 1 (1.2-2), the temperature of the cyclization reaction is controlled to be 0-50 ℃, preferably 10-40 ℃, the reaction time of the cyclization reaction is 1-5 hours, preferably 2-4 hours, and the mass ratio of the product formula (III) to the organic solvent 2 is 1 (1-50), preferably 1-20).
In embodiments of the invention, the Mitsunobu reaction in step 3) is carried out in the presence of an organic solvent 3, the organic solvent 3 is one or more of tetrahydrofuran, toluene, 1, 4-dioxane and N, N-dimethylformamide, preferably one or a mixture of of tetrahydrofuran and of 1, 4-dioxane, the molar ratio of the product of formula (IV) to triphenylphosphine is 1 (1-3), preferably 1 (1.5-2), the molar ratio of the product of formula (IV) to N-formyl-L-leucine (V) is 1 (1-3), preferably 1 (1.5-2), the molar ratio of the product of formula (IV) to diisopropyl azodicarboxylate is 1 (1-3), preferably 1 (1.5-2), the reaction temperature of the Mitsunobu reaction is controlled to be-30 ℃, preferably-20-30 ℃, the reaction time of the Mitsunobu reaction is 1-5-2, and the reaction time of the product of formula (IV) to diisopropyl azodicarboxylate is preferably 1 (1-3), and the reaction time of the product of formula (IV) to 3) is preferably 1-20-24 hours, and the reaction time of the organic solvent is preferably 1.5-2).
In a third aspect, the invention provides the use of orlistat impurity F shown as formula (I) as a reference substance in the quality research of orlistat bulk drug or orlistat preparation, the orlistat impurity F is used as a process impurity for preparing orlistat bulk drug, the structure of the orlistat impurity F is different from that of orlistat impurity D (VI) in USP standard of United states pharmacopoeia, the name of the impurity F is N-formyl-L-leucine- (3S,4R,6S) -3-hexyl-2-oxo-6-deca alkyl tetrahydro-2H-pyranyl ester, and the structure of the impurity F is shown as (VI)
The beneficial results of the invention are:
the invention provides orlistat impurity F and a preparation method thereof, the preparation method can prepare a large amount of orlistat impurity F, has good purity and high yield, and can be used as a reference substance for quality research, thereby better ensuring and controlling the quality of orlistat bulk drug or preparation thereof.
FIG. 1 shows the NMR spectrum of the product of formula (III), i.e. (2S,3S,5R) -2-hexyl-3, 5-dihydro-2H-hexadecanoic acid;
FIG. 2 shows the NMR spectrum of the product (IV), i.e. (3S,4S,6R) -3-hexyl-2-oxo-6-deca alkyltetrahydro-2H-pyranyl ester;
FIG. 3 shows the mass spectrum of orlistat impurity F of formula (I);
FIG. 4 shows the NMR spectrum of orlistat impurity F represented by formula (I);
FIG. 5 shows HPLC mixture mapping spectra of orlistat impurity F of formula (I), orlistat impurity D of formula (VI) and orlistat.
Embodiments of the present invention will be specifically described below by way of examples of the present invention.
In a 250ml reaction flask were added, in order, 120ml of tetrahydrofuran, (3S,4S) -3-hexyl-4- [2- (R) -hydroxy-tridecyl]-Oxetazetidines15g of (II) -2-ketone, 7g of water and 7g of sodium hydroxide, stirring and heating to 60 ℃ for reaction for 2 hours, evaporating the reaction solution at 45 ℃ under reduced pressure after the reaction is completed to remove part of the solvent, adding 150ml of ethyl acetate and 150ml of water into the residue, stirring, cooling in an ice bath, and dropwise adding hydrochloric acid to adjust the pH value to 2-3. Separating, washing an organic phase with 200ml of water, drying the organic phase by anhydrous sodium sulfate, filtering, and evaporating the filtrate at 45 ℃ under reduced pressure to dryness to obtain 14.5g of off-white solid, wherein the yield is as follows: 92.0 percent. The nuclear magnetic resonance of the reaction product (see FIG. 1) is1H-NMR(600MHz,CDCl3):δ4.08(m,1H),3.93(m,1H),2.46(m,1H),1.72～1.64(m,3H),1.61～1.55(brs,2H),1.46～1.42(m,2H),1.28～1.26(m,27H),0.89～0.87(s,6H)ppm.
Second step of
Adding 12g of (2S,3S,5R) -2-hexyl-3, 5-dihydro-2H-hexadecanoic acid (III), 9g of p-toluenesulfonic acid and 120ml of dichloromethane into a 250ml reaction bottle, stirring and reacting at 25-30 ℃ for 3 hours, adding 100ml of water into a reaction solution after the reaction is completed, separating, washing an organic phase with 10ml of water, drying the organic phase with anhydrous sodium sulfate, filtering, and evaporating the filtrate at 40 ℃ under reduced pressure to dryness to obtain 9.2g of an off-white solid, wherein the yield is as follows: 80.56 percent. The nuclear magnetic resonance of the reaction product (see FIG. 2) is1H-NMR(600MHz,CDCl3):δ4.38～4.35(m,1H),4.20～4.17(m,1H),2.46～2.38(m,2H),1.95～1.91(m,1H),1.74～1.70(m,1H),1.67～1.50(m,6H),1.48～1.26(m,24H),0.89～0.87(s,6H)ppm.
The third step
Adding 5g of N-formyl-L-leucine (V) into a 100ml reaction bottle, dissolving in 40ml of tetrahydrofuran, sequentially adding 8g of (3S,4S,6R) -3-hexyl-2-oxo-6-deca alkyltetrahydro-2H-pyranyl ester (IV) and 8g of triphenylphosphine, cooling to-20 ℃, dropwise adding 6g of diisopropyl azodicarboxylate, reacting at-20 to-10 ℃ for 12 hours, distilling at 45 ℃ under reduced pressure to dryness, adding 50ml of N-hexane and water into the residue50ml of the solution was stirred and dissolved, and the solution was separated into 2.66 to 2.63(m,1H), and the aqueous layer was extracted with 40ml of n-hexane. All organic layers were combined, washed with 100ml of an aqueous solution, separated, evaporated to dryness at 50 ℃ under reduced pressure, and the residue was purified by column chromatography (ethyl acetate: petroleum ether: 1: 5) to give 3.0g of an off-white solid. The nuclear magnetic resonance of the reaction product (see FIG. 4) is1H-NMR(600MHz,CDCl3) δ 8.21(s,1H),5.99 to 5.98(d, J ═ 6HZ,1H),5.07 to 5.05(M,1H),4.70 to 4.66(M,1H),4.47 to 4.43(M,1H),2.66 to 2.63(M,1H),1.96 to 1.90(M,2H),1.89 to 1.81(M,1H),1.79 to 1.65(M,3H),1.64 to 1.54(M,3H),1.47 to 1.37(M,2H),1.31 to 1.25(M,24H),0.97 to 0.96(M,6H),0.88 to 0.86(M,6H) ppm. (see FIG. 3) ESI-MS M/Z496.63 (M + H/H: 496.63(M, M + H)+)。
Mass Spectrometry (MS) detector apparatus described above: waters Acquity SQ Detector mass spectrometer, ion source: ESI+(ii) a Nuclear magnetic resonance hydrogen spectrum (1H NMR) instrumentation: agilent 600DD2(600MHz) high resolution nuclear magnetic resonance spectrometer, solvent: CDCl3(ii) a Internal standard: TMS; temperature: at 25 ℃.
The HPLC detection apparatus used in fig. 5 above: agilent 1260; HPLC chromatographic conditions: a chromatographic column: agilentZORBA XDB-C18,4.6 x 250mm,5 μm; mobile phase: acetonitrile: water 83: 17; a detector: 195 nm; column temperature: 30 ℃; sample introduction amount: 20 mu l of the mixture; flow rate: 1.0 ml/min; diluting liquid: acetonitrile; liquid phase retention time t of impurity D141.620 min; liquid phase retention time t of impurity F243.390 min; orlistat liquid phase retention time t3＝47.617min。
Finally, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that, while the invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.