Three-component synthesis of polysubstituted 6-azaindolines and its tricyclic derivatives.

[Reaction: see text] By simply heating a toluene solution of isocyanoacetamide (3), amine (4), and aldehyde (5), a clean three-component reaction occurred to provide the pyrrolidinone-fused azaindoline (2). In this multicomponent reaction, the isocyanoacetamide (3) reacted four times in a highly ordered manner creating three heterocylic rings with the concurrent formation of five chemical bonds and a minimal loss of molecular weight. Heating is the only external energy required to promote this powerful complexity-generating MCR.