Direct, four-step synthetic pathway to iheyamine A and several analogues.

A novel synthetic route toward the pentacyclic azepinobisindole alkaloid iheyamine A and its several analogues has been developed in four steps from commercially available isatins and tryptamines. This crucial transformation involves the Bischler-Napieralski cyclization to deliver the characteristic seven-membered framework. Then the ester intermediate undergoes a hydrolyzation-decarboxylation-dehydrogenation cascade to yield the final product.