Dioxirane Epoxidation of 10-Membered-Ring Stilbene Lactams as Synthetic Precursors to Protoberberines.

Abstract

Silylated stilbene lactams 1, prepared by intramolecular addition of an aryl radical to a trimethylsilylacetylene, were converted into protoberberines by dimethyldioxirane (DMD) epoxidation and subsequent acid-catalyzed cyclization of the epoxysilane with HCl. Treatment of the nonsilylated trans- and cis-stilbene derivatives with DMD afforded 13-hydroxytetrahydroprotoberberines and 13a-hydroxy-13-ketotetrahydroprotoberberines as the main products. Tetrahydroprotoberberines were also obtained in excellent yields by the reaction of both silylated and nonsilylated lactams with hydriodic acid.