Pyrroline Synthesis via Visible-Light-Promoted Hydroimination of Unactivated Alkenes with N,N′-Dimethylpropylene Urea as H-Donor

Synthesis of 3,4-pyrroline derivatives via visible-light-induced hydro/oxyimination of unactivated olefins is reported. In the presence of the photoredox catalyst fac-Ir(ppy)₃, the key iminyl radical intermediate can be readily generated from O-acyl oximes, and undergoes intramolecular cyclization and H-abstraction from solvent or is trapped by TEMPO to give the corresponding hydro/oxyimination product, respectively. Mechanistic investigations indicate that N,N′-dimethylpropylene urea (DMPU) works as both reducing agent for catalyst regeneration and H-donor for product formation in this process. (Figure presented.).