Preparing functional bis(indole) pyrazine by stepwise cross-coupling reactions: An efficient method to construct the skeleton of dragmacidin D

A direct approach for selective construction of properly substituted bis(indole) pyrazine, the skeleton of a marine alkaloid dragmacidin D, has been developed. The key steps involved the regioselective introduction of two indole units, using the palladium(0)-catalyzed Suzuki and the Stille cross-coupling reactions sequentially.