The Azaallylic Anion as a Synthon for Pd-Catalyzed Synthesis of Heterocycles: Domino Two- and Three-Component Synthesis of Indoles

摘要

Pd-catalyzed cross-coupling reactions represent some of the most powerful and versatile tools in modern synthetic organic chemistry.[1] While most of the cross-coupling processes are oriented toward the formation of C-C bonds, during the last decade, the new methodologies developed for the creation of C-N bonds have became extraordinarily popular, as they represent a very efficient entry into different types of important nitrogenated compounds.[2] On the other hand, the efforts of many prominent research groups have provided the synthetic organic chemist with highly active Pd catalytic systems of wide scope and enhanced stability.[3], [4] Thus, under the same reaction conditions, several different cross-coupling processes can be carried out consecutively with the same catalytic system. By taking advantage of this versatility of some Pd catalysts, and combining CC and CN bond-forming reactions, some new methodologies for the synthesis of heterocycles have been developed.[5], [6] For instance, we have recently reported a Pd-catalyzed cascade process which involves an alkenyl amination and a subsequent intramolecular Heck reaction, which together represent a new method for the synthesis of indoles.