Synthesis of Alkaloids, (±)-Xylopinine and (±)-Tetrahydropalmatine, by a Photo-Induced Rearrangement of Spirobenzylisoquinolines in the Presence of Vitamin C

Abstract

The presence of vitamin C during the photo-induced rearrangement reaction of spirobenzylisoquinolines in ethanol suppressed the formation of the oxidation product, improving the yield of the berbinium compound, which yields the tetrahydroprotoberberine type compound on reduction with sodium borohydride. Synthesis of two alkaloids, (±)-xylopinine and (±)-tetrahydropalmatine, was accomplished by this method in fair yield.