Photoactivated Formal [3 + 2]/[4+2] Cycloaddition of N-Aryl Cyclopropyl and Cyclobutylamines

Abstract

Organic transformations initiated by photochemical activation have been at the forefront of reaction discovery. In this study, we present a formal photochemical [3+2] and [4+2] cycloaddition using N-aryl cyclopropylamines and N-aryl cyclobutylamines in conjunction with α,β-unsaturated carbonyl systems, unveiling two distinct mechanistic pathways. The [3+2] cycloaddition is elucidated as being guided by the photochemical activity of an electron donor-acceptor (EDA) complex. Simultaneously, intermolecular [4+2] annulation of cyclobutylanilines is achieved by visible-light photoredox catalysis. These simple methodologies have wide applicability, facilitating the synthesis of N-arylaminocycloalkyl compounds in yields ranging from good to excellent.