Asymmetric synthesis of cis-4-aminobenzopyran derivatives catalyzed by N,N′-Dioxide-Sc(OTf)_3 complexes

摘要

The reactions of salicylaldimines with electron-rich alkenes (2,3-dihydro-2H-furan and 3,4-dihydro-2H-pyran) catalyzed by N,N′-dioxide-Sc(OTf)_3 complexes were investigated. The methodology was successfully applied to the asymmetric synthesis of cis-4-aminobenzopyran derivatives. Excellent yields, diastereo- and enantioselectivities were observed for a broad range of substrates under mild conditions (see scheme).