Ru(ii)-catalyzed synthesis of indolo[2,3-c]isoquinolines via [3+3] annulation of N,N′-cyclic azomethine ylides and 3-diazoindolin-2-imines

Abstract

A facile [3+3] annulation method for the construction of fused α-carboline or indolo[2,3-c]isoquinoline frameworks from easily synthesizable N,N′-cyclic azomethine ylides and 3-diazoindolin-2-imines using a Ru(II) catalyst is reported. This strategy was found to be efficient and effective for the syntheses of a variety of fused polycyclic molecules with a wide substrate scope, mild reaction conditions, and good to excellent yields. In addition, the mechanistic pathway of this transformation has been investigated by performing various control experiments with ESI-MS analyses.