反应详情

Intermediate 33 (0.724 g) in dichloromethane (5 ml) was treated with triethylamine (1.14 ml), forming a slurry which was added portion-wise over 5 min to a solution of 4-nitrophenyl chloroformate (0.444 g) in anhydrous dichloromethane (5 ml) at 0° C. under nitrogen. The stirring solution was allowed to warm to room temperature over 2 h, then filtered; the filtrate was purified directly by chromatography on silica gel (Biotage 90 g column), eluting with 35–40% ethyl acetate in cyclohexane, and appropriate fractions evaporated in vacuo to give the title compound (Isomer I) as an opaque yellow film (0.202 g).

1. customforming a slurry which
2. filtrationfiltered
3. customthe filtrate was purified directly by chromatography on silica gel (Biotage 90 g column)
4. washeluting with 35–40% ethyl acetate in cyclohexane, and appropriate fractions
5. customevaporated in vacuo