The first enantiospecific total synthesis of a C-quaternary voachalotine alkaloid, (+)-dehydrovoachalotine

Abstract

The first enantiospecific total synthesis of the indole alkaloid (+)-dehydrovoachalotine ( 1 ) has been achieved from d-(+)-tryptophan methyl ester in 28% overall yield. The formation of the prochiral quaternary carbon center at C-16 in the key intermediate ( 12 ) was realized via a Tollens reaction from N a-methylvellosimine ( 13 ) in 95% yield. This approach could also be applied to the synthesis of many other indole alkaloids that contain a quaternary carbon center at C(16).