Benzoyl chloride → (20S)-21-hydroxy-20-methylpregn-4-en-3-one benzoate

Participants

Reaction Steps

A solution of (20S)-21-hydroxy-20-methylpregn-4-en-3-one (8.0 g, 24.2 mmole) in dichloromethane (200 mL) was cooled in an ice-water bath and treated sequentially with triethylamine (3.69 mL, 26.6 mmole) and benzoyl chloride (3.09 mL, 26.6 mmole) and stirred for 16 hours at room temperature. After the reaction mixture was diluted with dichloromethane (200 mL), it was extracted with ether, dried over magnesium sulfate and filtered and the filtrate was concentrated to a solid which was purified by flash chromatography to give (20S)-21-hydroxy-20-methylpregn-4-en-3-one benzoate (9.4 g, 89.5%) melting at 193°-195° C. after recrystallization from acetone. IR 1716, 1676, 1614 (m), 1284 cm-1 ; MS (CI) 435 (100%, M+1), 313 (70%, M+1--PhCOOH); 1H NMR (CDCl3) δ 0.77 (3H, s, C18 --Me), 1.04 (d, C22 --Me), 1.19 (s, C19 --Me), 4.05 (1H, dd, 1/2 C21 --CH2), 4.34 (1H, dd, 1/2 C21 --CH2), 5.72 (1H, s, C4 --H), 7.45 (2H, t), 7.56 (1H, t), 8.04 (2H, dd).

Provenance & Evidence