Industrial process for the preparation of high purity estetrol

Abstract

The invention relates to the preparation of estetrol of formula (I), derivatives thereof protected at positions 3,15α,16α,17β of general formula (III), and 3-hydroxy derivatives thereof protected at positions 15α,16α,17β of general formula (IV), and to the intermediates of general formulae (III) and (IV) applied in the process. Another aspect of the invention is the use of estetrol of formula (I) obtained by the process of the invention for the preparation of a pharmaceutical composition. ##STR00001##

Claims

1. Process for the preparation of estetrol of formula (I), ##STR00014## starting from the compound of formula (II) ##STR00015## wherein the process comprises: (a) acylating a compound of formula (II) in a suitable solvent using a suitable reactant to give a compound of general formula (III); ##STR00016## wherein R=methyl group or hydrogen; (b) of removing a benzyl protecting group in position 3 by transfer hydrogenation or catalytic hydrogenation to give a compound of general formula (IV) ##STR00017## wherein R=methyl group or hydrogen; and (c) deprotecting the compound of formula (IV) in an alkaline medium with an alkali metal carbonate, alkali metal hydrogen carbonate, or alkali metal hydroxides in a suitable solvent.

2. The process according to claim 1, wherein the solvent used in step (a) is selected from the group consisting of aliphatic and aromatic hydrocarbons, halogenated hydrocarbons, esters, and ethers.

3. The process according to claim 1, wherein the reactant used in step (a) is acetic anhydride, acetyl chloride, acetyl bromide, or acetic acid-formic acid mixed anhydride.

4. The process according to claim 1, wherein step (a) is carried out in the presence of a tertiary amine base.

5. The process according to claim 1, wherein step (a) further comprises crystallizing the resulting compound of general formula (III) from C.sub.1-3 alcohols.

6. The process according to claim 1, wherein step (a) is carried out without the purification and/or isolation of the compounds of formula (II).

7. The process according to claim 1, wherein step (b) is carried out by catalytic hydrogenation with hydrogen gas, wherein the catalyst is selected from palladium or palladium on a support.

8. The process according to claim 7, wherein the catalytic hydrogenation uses a solvent selected from the group consisting of alcohols, esters, and ketones.

9. The process according to claim 1, wherein step (b) is carried out by transfer hydrogenation using a cyclohexene reagent.

10. The process according to claim 9, wherein the transfer hydrogenation uses an alcohol solvent.

11. The process according to claim 1, wherein step (b) further comprises crystallizing the resulting compound of general formula (IV) from esters, hydrocarbons, alcohols, or mixtures thereof.

12. The process according to claim 1, wherein the solvent used in step (c) is selected from the group consisting of water, an alcoholic solvent, or a mixture thereof.

13. The process according to claim 1, wherein the step (c) is carried out in the presence of an alkali metal carbonate, an alkali metal hydrogen carbonate, an alkali metal alcoholate, or an alkali metal hydroxide.

14. The process according to claim 1, wherein R is a methyl group.

15. The process according to claim 1, wherein R is hydrogen.

16. A compound selected from the group consisting of (15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyltriacetate, (15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyl triformiate, and (15α,16α,17β)-3-hydroxyestra-1,3,5(10)-triene-15,16,17-triyl triformiate.

Description

EXAMPLES

Example 1

(15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyl triacetate

Method A (Isolated)

a.) Cis-hydroxylation

(15α,16α,17β)-, and (15β,16β,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triol

(1) 40 mg potassium osmate dihydrate (K.sub.2OsO.sub.4.2H.sub.2O) was suspended in 100 mL of 2-butanone (methyl ethyl ketone) at 20-25° C. under N.sub.2 atmosphere and 7.7 mL of purified water and 1.1 g of trimethyl-amine N-oxide dihydrate was added thereto. 2.0 g (5.5 mmol) of 3-benzyloxy-estra-1,3,5(10),15-tetraene-17-ol (WO 2004/041839 (Pantarhei), Example 7) was dissolved in 40 mL of 2-butanon and added dropwise to the reaction mixture. The reaction mixture was then stirred at 20-25° C. for 28 hours under N.sub.2 atmosphere. The reaction was monitored by TPLC (n-heptane:acetone 1:1).

(2) Work-up: 25 mL of 10% Na.sub.2S.sub.2O.sub.5 solution was added to the mixture followed by the addition of 100 mg of activated carbon, then stirred for 1 hour. Filtered through a celite pad, then EtOAc and 10% of HCl solution were added. The phases were separated, the aqueous phase was extracted with EtOAc. The combined organic phases was washed with saturated NaCl and 10% Na.sub.2S.sub.2O.sub.5 solutions. Dried over Na.sub.2SO.sub.4, filtered, then concentrated. Thus, 1.8 g (81.8%) of product was obtained.

(3) Purity (HPLC): 85.0% ααβ-isomer, 9.9% βββ-isomer (area) (ratio 89.6:10.4)

b) Acylation

(15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triol triacetate

(4) 1.0 g (2.53 mmol) of (15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triol was dissolved in 15 mL of dichloromethane under N.sub.2 atmosphere. 1.5 mL of triethyl-amine, 6.0 mL of acetic acid and 72 mg of 4-dimethyllaminopyridin were added and stirred for 2 hours. The reaction was monitored by TLC (toluene:acetone 4:1).

(5) Work-up: 3 mL of ethanol was added dropwise to the mixture an stirred for 30 minutes, then 10% NaHCO.sub.3 solution was added and stirred for another 30 minutes. The phases were separated and the organic phase was washed twice with 10% NaHCO.sub.3 solution, then with saturated brine. Dried over Na.sub.2SO.sub.4, filtered and the solvent was changed to MeOH and crystallized therefrom. After filtration and drying 1.2 g of material was obtained. To obtain the appropriate isomer ratio the product was recrystallized twice more from methanol, thus 1.1 g (84.46%) of product was obtained.

(6) Purity (HPLC): 99.2% ααβ-isomer, 0.14% βββ-isomer (area).

Method B (without Isolation)

a) Cis-Hydroxylation

(15α,16α,17β), (15β,16β,17β) Isomeric Mixture of 3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triol

(7) 30.03 g (83.3 mmol) of 3-benzyloxy-estra-1,3,5(10),15-tetraene-17-ol (WO 2004/041839 (Pantarhei), Example 7) was dissolved in 480 mL of 2-butanon (methyl ethyl ketone) at 20-25° C. under N.sub.2 atmosphere, then 600 mg of potassium osmate dihydrate (K.sub.2OsO.sub.4.2H.sub.2O), 48.0 mL of purified water and 16.5 g of trimethylamine N-oxide dihydrate were added. The reaction mixture was then stirred at 40-45° C. for 7 hours under N.sub.2 atmosphere. The reaction was monitored by TLC (n-heptane:acetone 1:1).

(8) Work-up: 300 mL of 10% (w/v) sodium metabisulfite solution (sodium pyrosulfite) was added dropwise to the mixture at 40-45° C. and stirred for 1 hour. The slurry was then filtered through a celite pad and the filter was washed with 2-butanone. The 2-butanone was then removed from the filtrate by distillation. 600.0 mL of ethyl acetate and 300 mL of 10% (w/v) sodium hydrogen carbonate solution (30 g NaHCO.sub.3) was added to the residue, after stirring vigorously for a few minutes and then settling, the phases were separated. The aqueous phase was washed twice with ethyl acetate. The combined organic phase was washed with a mixture of 1% (w/v) EDTA-tetraNa salt solution and saturated brine. After separation of the phases, the ethyl acetate organic phase was concentrated to a final volume of 450 mL, thereby dehydrated also. The product was not isolated but further transferred to an acylation reaction.

b) Acylation

(15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyl triacetate

(9) 72.0 mL of acetic anhydride, 48 mL of triethylamine and 1.8 g of 4-dimethylaminopyridine were added to the ethyl acetate solution obtained in step a), followed by stirring at 35-40° C. for 3 hours under N.sub.2 atmosphere. The reaction was monitored by TLC (toluene:acetone 4:1).

(10) Work-up: 24 mL of ethanol was added dropwise to the mixture, stirred for 30 minutes, then cooled to 20-25° C., followed by the addition of 240 mL of purified water and 60 mL of 10% (w/v, d=1.047, 17.88 g cc.HCl) hydrochloric acid solution and after a few minutes of vigorous stirring and then settling, the phases were separated. The aqueous phase was extracted with ethyl acetate. The combined organic phase was washed with a mixture of 10% (w/v) sodium hydrogen carbonate solution and saturated brine, and the phases were separated. The organic phase was dried over Na.sub.2SO.sub.4, clarified with alumina, silica gel and activated carbon and stirred at 20-25° C. for 1 hour. The clarifiers were then filtered off and the filter was washed with ethyl acetate.

(11) The filtrate was concentrated under reduced pressure, then the solvent was concentrated and distilled to change the solvent to methanol, and finally the material was crystallized from pure methanol. The obtained crude product was recrystallized without drying.

c) Recrystallization

(12) The crude product obtained in step b) was dissolved in dichloromethane, methanol was distilled off and finally crystallized from pure methanol. The operation was repeated once more. Thus, 30.4 g (69.8%) of white crystals was obtained.

(13) Purity (HPLC): 99.2% ααβ-isomer, 0.14% βββ-isomer (area).

(14) Mp.: 156.5-157.5° C.

(15) EI-HRMS: Calcd for C.sub.31H.sub.36O.sub.7 [M.sup.+]: 520.24555; found: 520.24459; delta=−1.86 ppm.

(16) .sup.1H NMR (499.9 MHz, CDCl.sub.3) δ=5.39 (1H, dd, J=8.4 Hz, J=6.6 Hz, H-16), 5.16 (1H, dd, J=10.4 Hz, J=8.4 Hz, H-15), 5.01 (1H, d, J=6.6 Hz, H-17), 2.08 (3H, s, 17-acetyl), 2.06 (3H, s, 15-acetyl), 2.04 (3H, s, 16-acetyl), 0.94 (3H, s, H-18)

(17) .sup.13C NMR (125.7 MHz, CDCl.sub.3) δ=169.8 (17-acetyl CO C-20), 169.0 (15-acetyl CO), 168.7 (16-acetyl CO), 83.1 (C-17), 72.5 (C-16), 69.8 (C-15), 51.4 (C-14), 39.2 (C-13), 19.9 (17-acetyl-CH.sub.3), 19.7 (15-acetyl-CH.sub.3), 19.6 (16-acetyl-CH.sub.3), 13.5 (C-18)

Example 2

(15α,16α,17β)-3-hydroxyestra-1,3,5(10)-triene-15,16,17-triyl triacetate

(18) Method A

(19) 25.7 g (49.36 mmol) of (15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyl triacetate (Example 1) was dissolved in 315 mL of ethyl acetate at 20-25° C. under N.sub.2 atmosphere. 770 mg of 10% palladium-on-carbon catalyst was suspended in 19 mL of deep-frozen ethyl acetate, and then added to the solution. The N.sub.2 atmosphere was changed to H.sub.2 atmosphere and the reaction mixture was stirred at 20-25° C. for 3 hours under atmospheric pressure.

(20) Work-up: The catalyst was filtered off, washed with ethyl acetate and concentrated to a final volume under reduced pressure, then n-heptane was added and the suspension was kept at 0-5° C. for 1 hour, then filtered and the crystalline product was washed on the filter with n-heptane, and dried at 40° C. in vacuum to constant weight. Thus, 19.88 g (93.55%) of white crystalline product was obtained.

(21) Purity (HPLC): 99.42% ααβ-isomer, 0.04% βββ-isomer (area).

(22) Method B

(23) 0.5 g of (15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyl triacetate (Example 1) was suspended in 14 mL of ethanol at 20-25° C., then 0.5 mL of cyclohexene and 38 mg of 10% Pd/C catalyst was added, followed by stirring at reflux temperature for 1 hour. The reaction was monitored by TLC (toluene:acetone 4:1).

(24) Work-up: The catalyst was filtered off from the reaction mixture and the mixture was concentrated to dryness. Thus, 0.41 g (99.17%) of white crystalline product was obtained.

(25) Purity (HPLC): 97.99% ααβ-isomer, 0.14% βββ-isomer (area).

(26) Mp.: 181.5-185.5° C.

(27) EI-HRMS: Calcd for C.sub.24H.sub.30O.sub.7 [M.sup.+]: 430.19860; found: 430.19927; delta=1.55 ppm.

(28) .sup.1H NMR (499.9 MHz, CDCl.sub.3) δ=5.41 (1H, dd, J=8.4 Hz, J=6.6 Hz, H-16), 5.18 (1H, dd, J=10.5 Hz, J=8.4 Hz, H-15), 5.03 (1H, d, J=6.6 Hz, H-17), (3H, s, 17-acetyl), 2.10 (3H, s, 15-acetyl), 2.07 (3H, s, 16-acetyl), 1.77 (1H, t, J=11.1 Hz, H-14), 0.95 (3H, s, H-18)

(29) .sup.13C NMR (125.7 MHz, CDCl.sub.3) δ=170.9 (17-acetyl CO), 170.1 (15-acetyl CO), 169.8 (16-acetyl CO), 84.1 (C-17), 73.5 (C-16), 70.8 (C-15), 52.4 (C-14), 40.2 (C-13), 20.9 (17-acetyl-CH.sub.3), 20.7 (15-acetyl-CH.sub.3), 20.6 (16-acetyl-CH.sub.3), 14.5 (C-18)

Example 3

(15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyl triformiate

(30) 5.00 g of (15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triol (Example 1, Method “A”, step a)) was dissolved in 73 mL of pyridine, and cooled to 0° C., then a mixture of a mixed anhydride made of 49 mL of formic acid and 18.3 mL of acetic anhydride cooled to 0° C. was added via an addition funnel at between 0-10° C. in ca. 25 minutes. After stirring for 1 hour 305 mL of water was added to the reaction mixture, and the resulting white precipitate was filtered off and washed with water. The dry crude product weighted 5.65 g (93.23%).

(31) The crude product—according to Example 1 Method B step c)—was recrystallized from methanol to give 3.92 g (69.4%) of the pure title product as white crystal.

(32) Purity (HPLC): 99.2% ααβ-isomer, 0.05% βββ-isomer (area).

(33) Mp.: 153.5-154.3° C.

(34) EI HRMS: M=478.19866; delta=0.06 ppm; C.sub.28H.sub.30O.sub.7

(35) .sup.1H NMR (499.9 MHz, CDCl.sub.3) δ=5.41 (1H, dd, J=8.4 Hz, J=6.6 Hz, H-16), 5.18 (1H, dd, J=10.5 Hz, J=8.4 Hz, H-15), 5.03 (1H, d, J=6.6 Hz, H-17), (3H, s, 17-acetyl), 2.10 (3H, s, 15-acetyl), 2.07 (3H, s, 16-acetyl), 1.77 (1H, t, J=11.1 Hz, H-14), 0.95 (3H, s, H-18)

(36) .sup.13C NMR (125.7 MHz, CDCl.sub.3) δ=170.9 (17-acetyl CO), 170.1 (15-acetyl CO), 169.8 (16-acetyl CO), 84.1 (C-17), 73.5 (C-16), 70.8 (C-15), 52.4 (C-14), 40.2 (C-13), 20.9 (17-acetyl-CH.sub.3), 20.7 (15-acetyl-CH.sub.3), 20.6 (16-acetyl-CH.sub.3), 14.5 (C-18)

Example 4

(15α,16α,17β)-3-hydroxyestra-1,3,5(10)-triene-15,16,17-triyl triformiate

(37) 5.0 g of (15α,16α,17β)-3-(benzyloxy)estra-1,3,5(10)-triene-15,16,17-triyl triformiate (Example 3) was dissolved in 150 mL of ethyl acetate at 20-25° C. under N.sub.2 atmosphere. 380 mg of 10% Pd/C catalyst was suspended in 5 mL of deep-frozen ethyl acetate and added to the solution. The N.sub.2 atmosphere was changed to H.sub.2 atmosphere and the reaction mixture was stirred at 20-25° C. for 4 hours under atmospheric pressure.

(38) Work-up: The catalyst was filtered off and the reaction mixture was concentrated to a quarter (38 mL) under reduced pressure, then 52 mL of n-heptane was added. After stirring at 0-5° C. for 1 hour, it was filtered and washed on the filter twice with 16 mL of n-heptane, dried to constant weight, thus, 3.51 g (94%) of white crystalline product was obtained.

(39) Purity (HPLC): 99.42% ααβ-isomer, 0.04% βββ-isomer (area).

(40) Mp.: 234-235° C.

(41) MS: M-H=387 (ESI)

(42) .sup.1H NMR (499.9 MHz, DMSO-d.sub.6) δ=8.17 (1H, s, 17-formyl-H), 8.09 (1H, s, 15-formyl-H), 8.04 (1H, s, 16-formyl-H), 5.52 (1H, t, J=7.4 Hz, H-16), 5.24 (1H, dd, J=10.1 Hz, J=8.6 Hz, H-15), 5.11 (1H, d, J=6.5 Hz, H-17), 0.99 (3H, s, H-18)

(43) .sup.13C NMR (125.7 MHz, DMSO-d.sub.6) δ=159.5 (17-formyl-C), 159.3 (15-formyl-C), 158.8 (16-formyl-C), 82.4 (C-17), 71.7 (C-16), 69.2 (C-15), 51.3 (C-14), 39.6 (C-13), 13.5 (C-18)

Example 5

Estetrol ((15α,16α,17β)-estra-1,3,5(10)-triene-3,15,16,17-tetrol)

(44) Method A

(45) 19.88 g (46.18 mmol) of (15α,16α,17β)-3-hydroxyestra-1,3,5(10)-triene-15,16,17-triyl triacetate (Example 2) was suspended in 596 mL of methanol at 20-25° C. under N.sub.2 atmosphere, then 19.88 g potassium carbonate was added portionwise and stirred for 3 hours. The reaction was monitored by TLC (n-heptane:acetone 1:1).

(46) Work-up: 14.91 mL of cc. acetic acid was added to the mixture and stirred for 30 minutes, after adding 298 mL of water the methanol was removed by distillation, then the precipitated crystals were kept at 0-5° C. for 1 hour, filtered and washed with water on the filter. It was then dried at 40° C. under vacuum to constant weight. Thus, 13.66 g (97.22%) of white crystalline product was obtained.

(47) Purity (HPLC): 99.67% ααβ-isomer, 0.04% βββ isomer (area), all contaminants <0.10%

(48) Method B

(49) 5 g (12.87 mmol) of (15α,16α,17β)-3-hydroxyestra-1,3,5(10)-triene-15,16,17-triyl triformiate (Example 4) was suspended in 150 mL of methanol at 20-25° C. under N.sub.2 atmosphere, then 5.34 g (38.6 mmol) of potassium carbonate was added portionwise and stirred for 3 hours. The reaction was monitored by TLC (n-heptane:acetone 1:1).

(50) Work-up: 4 mL of acetic acid was added to the mixture and stirred for 30 minutes, after adding 75 mL of water the methanol was removed from the mixture by distillation, the precipitated crystals were kept at 0-5° C. for 1 hour, then filtered and washed on the filter twice with 5 mL of 0-5° C. water. It was then dried at 40° C. under vacuum to constant weight. Thus, 3.80 g (97%) of white crystalline product was obtained.

(51) Purity (HPLC): 99.67% ααβ-isomer, 0.04% βββ isomer (area), all contaminants <0.10%

(52) Mp.: 240-243° C.

(53) EI-HRMS: Calcd for C.sub.18H.sub.24O.sub.4[M.sup.+]: 304.16691; found: 304.16716; delta=0.82 ppm.

(54) .sup.1H NMR (499.9 MHz, DMSO-d.sub.6) δ=4.86 (1H, d, J=4.8 Hz, OH (17)), 4.61 (1H, br s, OH (16)), 4.26 (1H, br d, J=3.3 Hz, OH (15)), 3.55-3.78 (2H, m, H-16, 15), 3.25 (1H, dd, J=5.7, 4.7 Hz, H-17), 1.05 (1H, dd, J=10.9 Hz, J=9.4 Hz, H-14), 0.67 (3H, s, H-18)

(55) .sup.13C NMR (125.7 MHz, DMSO-d.sub.6) δ=86.3 (C-17), 75.0 (C-16), 69.2 (C-15), 55.5 (C-14), 39.5 (C-13), 14.0 (C-18)