Visible-Light-Induced Transition-Metal-Free Nitrogen-Centered Radical Strategy for the Synthesis of 2-Acylated 9H-Pyrrolo[1,2-a]indoles

A convenient and efficient visible-light-induced tandem acylation/cyclization of N-propargylindoles with aryl- or alkyl-substituted acyl oxime esters for the synthesis of 2-acyl-substituted 9H-pyrrolo[1,2-a]indoles under transition-metal-free conditions, which proceeds via nitrogen-centered radical-mediated cleavage of the C-C σ-bond in acyl oxime esters, is established. The aryl or alkyl acyl radicals, which come from acyl oxime esters, attack the C-C triple bonds in N-propargylindoles and then go through intramolecular cyclization/isomerization.