Synthesis of vinca alkaloids and related compounds. Part 102: Simple synthesis and ring transformation of (+/-)-minovincine. First synthesis of (+/-)-vincaminine

摘要

A molecule with an indole skeleton, containing a latent acrylic ester function-acting as a diene-readily reacted with benzoic acid (4-bromomethylene-5-oxo)hexyl ester that had been built up from pentane-2,4-dione. Dehydration of the enamine and subsequent [4+2] cycloaddition supplied epimers having the D-secoaspidospermane skeleton. These compounds directly or after epimerization gave (+/-)-minovincine. Oxidative ring transformation of (+/-)-minovincine under different conditions led to (+/-)-16-acetyl-16-deethylapovincamine and (+/-)-vincaminine. (C) 2003 Elsevier Ltd. All rights reserved. [References: 16]