DBU-promoted [4 + 3] annulation of pyrrole-2-carbaldehyde derivatives with indene-2-carbaldehydes: synthesis of indene-fused pyrrolo[1,2-a]azepines

Abstract

A base-promoted [4 + 3] annulation of pyrrole-2-carbaldehydes with indene-2-carbaldehydes has been developed for synthesizing indene-fused pyrrolo[1,2-a]azepines. The reaction proceeds under mild conditions and demonstrates a remarkably broad substrate scope, accommodating a wide range of functional groups with excellent tolerance. In addition, the photophysical properties of the synthesized compounds (3aa–3na, 3ab–3ap) were preliminarily investigated.