反应详情

Glycine methyl ester hydrochloride (89 mg, 0708 mmol) with triethylamine (0.072 mL) and 5β-pregnane-3,20-dione (200 mg, 0.632 mmol) were mixed in neat titanium (IV) isopropoxide (302 mg, 1.06 mmol) and dry toluene (0.4 mL). The mixture was stirred under nitrogen for 3 h. Methanol (2.8 mL) was added. Then NaBH4 (38 mg, 1.01 mmol) was carefully added. After 5 min the reaction was finished by adding 0.1 N NaOH. The resulting mixture was filtered through Celite, and the residue was washed with ether (2×30 mL) and ethyl acetate (2×30 mL). The organic layer was separated, dried (MgSO4) and the solvents were removed under reduced pressure. The residue was purified on preparative TLC (5 plates, 200×200×0.3 mm) in a mixture of toluene-ethyl acetate (1:1) to afford 43 mg (17%). 1H NMR (400 MHz, CDCl3): δ 0.59 (s, 3H, H-18); 0.92 (s, 3H, H-19); 2.11 (s, 3H, H-21); 2.45-2.53 (m, 1H, H-3); 2.52 (t, 1H, J=8.8, H-17); 3.46 (s, 2H, H-2′); 3.74 (s, 3H, OMe). 13C NMR (100 MHz, CDCl3): δ 13.34 (C-18); 20.77; 22.86; 23.45; 24.40; 26.37; 27.15; 27.87; 31.45; 34.00; 35.08; 35.69; 35.83; 39.22; 40.29; 42.09; 44.27; 48.09; 51.74; 56.70; 57.24; 63.86; 173.13 (C-1′); 209.51 (C-20). The product was subsequently characterised as hydrochloride. [α]D=+61.9 (c 0.24, CHCl3).IR (CHCl3): 2708 (N+H2), 1758 (C═O, ester), 1698 (C═O, COCH3). 1235 (C—O, ester). MS-ESI: 390.2 [100%, M+H]+; (HR) for [C24H40NO3+H]+ m/z calculated: 390.3003. found: 390.3002.

1. waitAfter 5 min the reaction was finished
2. filtrationThe resulting mixture was filtered through Celite
3. washthe residue was washed with ether (2×30 mL) and ethyl acetate (2×30 mL)
4. customThe organic layer was separated
5. dry with materialdried (MgSO4)
6. customthe solvents were removed under reduced pressure
7. customThe residue was purified on preparative TLC (5 plates, 200×200×0.3 mm) in a mixture of toluene-ethyl acetate (1:1)
8. customto afford 43 mg (17%)