SYNTHESIS OF VINCA ALKALOIDS AND RELATED COMPOUNDS 103.RECOGNITION OF AN UNEXPECTED REACTION AND ITS APPLICATION IN BUILDING THE ASPIDOSPERMANE SKELETON.SIMPLE SYNTHESIS OF 15beta-HYDROXYVINCADIFFORMINE

摘要

Reaction of tryptamine derivative (2b) and acetate ester (11) built up from 2-(chloromethylene)butanal (4) resulted in enamino ketone (14).Dehydration of 14 and subsequent intramolecular [4+2] cycloaddition led to 15-oxovincadifformine (15).Regio- and stereoselective reduction of the latter molecule supplied 15beta-hydroxyvincadifformine (1).