Synthesis of (+)-febrifugine and a formal synthesis of (+)-halofuginone employing an organocatalytic direct vinylogous aldol reaction

摘要

The enantioselective organocatalytic direct vinylogous aldol reaction of γ-crotonolactone and a suitable aldehyde was utilized in the synthesis of a functionalized γ-butenolide. The γ-butenolide (aldol product) was stereoselectively converted into a 5-aminoalkyl butyrolactone, which isomerized to the key 2,3-disubstituted piperidinone, a common intermediate to (+)-febrifugine and (+)-halofuginone.