反应详情

Paraformaldehyde (660 mg; WAKO) was added to a formic acid (50 mL) solution of Intermediate 4 (4.33 g) at 50° C. and the resulting mixture was stirred as it was for 13 hours and 30 minutes. The solvent was evaporated under reduced pressure followed by the addition of dichloromethane (100 mL) and 1 N aqueous sodium hydroxide solution (100 mL) to extract the reaction mixture, and the aqueous layer was further extracted with dichloromethane. The organic layer was combined and dried and then the solvent was evaporated under reduced pressure to give the title compound (4.49 g).

1. customThe solvent was evaporated under reduced pressure
2. additionfollowed by the addition of dichloromethane (100 mL) and 1 N aqueous sodium hydroxide solution (100 mL)
3. extractionto extract the reaction mixture
4. extractionthe aqueous layer was further extracted with dichloromethane
5. customdried
6. customthe solvent was evaporated under reduced pressure