Photocatalytic, α-Aminoalkyl Radical-Mediated, Methylene-Extrusive Ring-Closing Transformation of o -Alkynyl and o -Cyano Acrylamides.

Herein we report a visible-light-induced, α-aminoalkyl radical-mediated cascade reaction of 1,7-enynes that establishes a unique ring-closing enyne transformation pathway which occurs with concomitant loss of a methylene moiety. The α-aminoalkyl radical derived from N , N -dimethylaniline was demonstrated to be a traceless promoter of enyne reorganization leading to 4-alkylquinolinones. The reaction can also be extended to nitrile-substituted acrylamide systems, leading to carbostyrils. Experiments with deuterated N , N -dimethylaniline- d 6 (PhN(CD 3 ) 2 ) established the involvement of 1,5-H atom transfer in the mechanism.