Design of an aryne-platform for the synthesis of non-racemic heterocyclic allocolchicinoids.

A four-step semisynthetic approach towards a highly versatile allocolchicine-related chiral aryne intermediate starting from naturally occurring colchicine was developed, and some of its synthetic transformations were studied. The generated benzyne intermediate afforded a number of non-racemic heterocyclic allocolchicinoids, which were shown to exhibit potent cytotoxicity towards COLO 357, OSA and Raji cells. The proposed methodology is attractive for the synthesis of libraries of new cytotoxic tubulin inhibitors.