Visible-Light-Induced Ruthenium Catalytic Strategy for C-H Activation and Aza-Michael Addition of 2-Arylquinazolin-4(3H)-ones with Olefins.

Abstract

A visible-light-mediated versatile synthesis of pyrrolo[2,1-b]quinazolin-9(1H)-one derivatives has been developed by merging Ru(II)-catalysis with photocatalysis via C-H activation and intramolecular aza-Michael addition of 2-arylquinazolin-4 (3H)-ones with various activated olefins under ambient reaction conditions with high efficiency and good functional-group tolerance. Mechanistic investigations were conducted through control experiments, UV-visible spectroscopy, H/D labeling studies, kinetics isotope-effect experiments, electron paramagnetic resonance (EPR), and light on-off studies to gain insight into the reaction pathway and the role of photocatalysis in the transformation. The present methodology was demonstrated to be effective for scale-up synthesis, enabling the efficient synthesis of the cyclized product, thereby highlighting its practical synthetic applicability.