反应详情

温度

4 °C

In a similar method to that described by Khan et al., (Khan, et al., 1996; incorporated herein by reference), to a stirred solution of penta-O-acetyl mannose (30.13 g, 77.3 mmol) in acetonitrile (300 ml) at 4° C. was added hydrazine monohydrate (1.2 eq, 4.65 g, 4.51 ml). The reaction mixture was maintained at 4° C. in a refrigerator for ˜16 hours whereupon it was filtered through a column (40×90 mm) of celite (25 g) atop flash silica gel (20 g) which was then washed with dichloromethane (300 ml). The filtrates were combined and the solvent removed under reduced pressure and the residue adsorbed onto flash silica (˜30 g). This was placed on a column (70×140) of flash silica (50 g) and eluted with 10% ethyl acetate/light petroleum (400 ml, f1), 50% ethyl acetate/light petroleum (2×600 ml f2 & 3), 100% ethyl acetate (400 ml, f4) and 25% methanol/dichloromethane (400 ml, f5). Most the required product, acetic acid 3,5-diacetoxy-2-acetoxymethyl-6-hydroxy-tetrahydro-pyran-4-yl ester (26.89 g, 77.1 mmol was found in f2. This compound (26.83 g, 77.1 mmol), in accordance with the method described by Mata et al. (Mata et al., 1992; incorporated herein by reference), was stirred with Meldrum's Acid (2.1 eq, 23.9 g) and triethylamine (2 eq, 15.6 g, 22.0 ml) in acetonitrile (200 ml) at 40-50° C. for ˜60 hours. The solvent was then removed, acetic acid/water (9:1, 300 ml) was added to the residue and then heated at 100° C. for ˜3 hr. After the solvent was removed the residue was dissolved in dichloromethane (300 ml) and washed with water (2×300 ml) and extracted with saturated sodium bicarbonate solution (2×200 ml). The combined bicarbonate layer was carefully acidified with HCl (5M, ˜pH=3), upon standing a solid formed and was filtered off to give the required compound (3,4,5-triacetoxy-6-acetoxymethyl-tetrahydropyran-2-yl)-acetic acid (10.73, 36%). 1Hnmr (500 MHz, CDCl3): δ 1.99 (s, 3H), 2.05 (s, 3H), 2.09 (s, 3H), 2.20 (s, 3H), 2.51 (dd, J=5.0, 16.0 Hz, 1H), 2.69 (dd, J=8.0, 16.5 Hz, 1H), 3.70 (ddd, J=2.0, 5.5, 9.5 Hz, 1H), 4.11, (dd, J=2.5, 12.5 Hz, 1H), 4.13 (dd, J=5.5, 7.5 Hz, 1H), 4.26 (dd, J=5.5, 12.0 Hz, 1H), 5.11 (dd, J=3.5, 10.0 Hz, 1H), 5.23 (t, J=10.0 Hz, 1H), 5.40 (d, J=3.5 Hz, 1H); ESMS (+ve) 413 (M+Na). This compound (5.15 g, 13.3 mmol) was dissolved in dichloromethane (200 ml) to this was added phenylalanine methyl ester hydrochloride (1.1 eq, 3.15 g), triethylamine (2.3 eq, 3.2 g, 4.3 ml), hydroxy succinimide (1.1 eq, 1.69 g) and dicyclohexylcarbodiimide (1.6 eq, 4.72 g). The reaction was stirred overnight, filtered and then extracted with water (2×200 ml), hydrochloric acid (1M, 2×200 ml), and water (2×200 ml). The organic layer was dried (sodium sulfate), filtered and evaporated under reduced pressure. The residue was adsorbed on ˜10 g silica gel, placed on a column (70 140 mm) of silica gel (50 g) and eluted with 25% light petroleum/dichloromethane (400 ml, f1), 50% light petroleum/dichloromethane (800 ml, f2[400 ml] & f3[400 ml]), 100% dichloromethane (800 ml, f4[400 ml, f5[400 ml]), 5% methanol/dichloromethane (400 ml, f6), 10% methanol/dichloromethane (400 ml, f7) and 100% methanol (400 ml, f8). The product was found in f6 and was dissolved in diethyl ether (2×200 ml), the insoluble reaction by-product was filtered off and the solvent was removed to give 3-phenyl-2-[2-(3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-2-yl)-acetylamino]-propionic acid methyl ester (7.09 g, 97%). This compound (7.87 g, 14.3 mmol) was dissolved in dry methanol (50 ml) and sodium methoxide (550 mg) was added. The reaction was followed by thin layer chromatography and after 1 hour Dowex 50W X8 H+ form ion exchange resin was added and after a further 30 min the reaction mixture was filtered and the solvent removed to give 3-phenyl-2-[2-(3,4,5-trihydroxy-6-hydroxymethyl-tetrahydro-pyran-2-yl)-acetylamino]-propionic acid methyl ester (4.80 g, 88%). To this material (4.80 mg, 12.5 mmol) in pyridine (50 ml) was added trityl chloride (2.5 eq, 8.63 g) and the mixture stirred at 50° C. overnight. After cooling to room temperature acetic anhydride (8 eq, 10.5 g) was added and the mixture stirred 3 hours, whereupon it was added to ice cold water (200 ml) and extracted with dichloromethane (3×200 ml). The organic phase was dried (sodium sulfate), filtered and evaporated under reduced pressure to give impure 3-phenyl-2-[2-(3,4,5-triacetoxy-6-trityloxymethyl-tetrahydro-pyran-2-yl)-acetylamino]-propionic acid. The entire amount of this material was stirred at room temperature with anhydrous ferric chloride (8.89 g) in dichloromethane (100 ml) for 1.5 hours, whereupon water (100 ml) was added and the mixture extracted with chloroform (3×200 ml). The organic extracts were combined and dried (sodium sulfate), filtered and the filtrate evaporated under reduced pressure. The residue was vacuum chromatographed on a silica gel (0.063-0.2 mm) column (2×30 cm), eluted with 10% ethyl acetate/light petroleum (300 ml, f1), 100% dichloromethane (350 ml, f2), 10% methanol/dichloromethane (350 ml, f3) and 100% methanol (150 ml, f4) to give 3-phenyl-2-[2-(3,4,5-triacetoxy-6-hydroxymethyl-tetrahydro-pyran-2-yl)-acetylamino]-propionic acid methyl ester (5.24 g, 82%). This compound (5.02 g, 9.86 mmol) was dissolved in dichloromethane (75 ml) and pyridine (0.86 g) and the mixture cooled to 0° whereupon phosphorus oxychloride (2.2 eq, 3.2 g) was added dropwise with stirring under a dry nitrogen atmosphere. The mixture was allowed to warm to room temperature and stirred overnight. The mixture was filtered and evaporated to dryness under reduced pressure. The residue was dissolved in a 1:1 mixture of acetone and water (80 ml) and kept at 45-50° for 2 hours. After evaporation to dryness the residue was evaporated from 50 ml of ethanol. This material was stirred at room temperature overnight in methanol (100 ml) that contained sodium methoxide (4 eq, 2.18 g) and water (2 ml), after which it was treated with a strong cationic exchange resin (Dowex 50W H+ form) to remove sodium ions. The ion exchange resin was filtered off and the filtrate taken to dryness under reduced pressure and the residue evaporated from ethanol (50 ml) to give methyl 3-phenyl-2-[2-(3,4,5-trihydroxy-6-phosphonooxymethyl-tetrahydro-pyran-2-yl)-acetylamino]-propionic acid. This material was then dissolved in a minimum of water and added dropwise to a solution of sodium acetate (7.4 g) in ethanol (500 ml). The resulting precipitate was pelleted by centrifugation and the ethanol decanted off, the solid was washed with diethyl ether (2×100 ml) and dried to give 3-phenyl-2-[2-(3,4,5-trihydroxy-6-phosphonooxymethyl-tetrahydro-pyran-2-yl)-acetylamino]-propionic acid monosodium salt (2.19 g, 47%). 1Hnmr (500 MHz, D2O): δ 2.44-2.66 (m, 2H), 2.86 (dd, J=4.0, 18.0 Hz, 2H), 3.06-3.15 (m, 1H), 3.40-3.46 (m, 1H) 3.48-3.55 (m, 1H), 3.80-3.92 (m, 3H), 3.94-4.02 (m, 1H), 4.47 (dd, J=1.5, 4.0 Hz, 1H), 7.11-7.31 (m, 5H); ESMS (−ve) 448 (M−H).

1. customat 4° C.
2. filtrationwas filtered through a column (40×90 mm) of celite (25 g) atop flash silica gel (20 g) which
3. washwas then washed with dichloromethane (300 ml)
4. customthe solvent removed under reduced pressure
5. washeluted with 10% ethyl acetate/light petroleum (400 ml, f1), 50% ethyl acetate/light petroleum (2×600 ml f2 & 3), 100% ethyl acetate (400 ml, f4) and 25% methanol/dichloromethane (400 ml, f5)
6. customThe solvent was then removed
7. additionacetic acid/water (9:1, 300 ml) was added to the residue
8. temperatureheated at 100° C. for ˜3 hr
9. customAfter the solvent was removed the residue
10. dissolutionwas dissolved in dichloromethane (300 ml)
11. washwashed with water (2×300 ml)
12. extractionextracted with saturated sodium bicarbonate solution (2×200 ml)
13. customformed
14. filtrationwas filtered off