Photoredox-Catalyzed Acylation/Cyclization of 2-Isocyanobiaryls with Oxime Esters for the Synthesis of 6-Acyl Phenanthridines

Abstract

An efficient acylation/cyclization reaction of 6-acyl phenanthridines with oxime esters using photoredox catalysis has been developed. This radical acyl transfer strategy enables a facile access to acyl-substituted phenanthridines with good yield and excellent selectivity. The developed method is redox neutral and has broad substrate scope and excellent functional group tolerance.

Chromium-catalyzed allylic defluorinative acylation of trifluoromethyl-substituted alkenes with acyl oxime esters

“…In 2019, Wu et al disclosed that acyl radicals can be generated from acyl oxime esters via photocatalyst-mediated reduction. 14 Relying on this discovery, acyl oxime derivatives have been successfully utilized as an acyl radical precursor in various acylation reactions of alkenes, 15 alkynes, 16 arenes, 17 isocyanides, 18 or thiophenols 19 under photocatalytic conditions in the last lustrum (Scheme 1B). Inspired by these elegant works and our ongoing research interest in transition metal-catalyzed reductive allylic defluorinative reactions, we envisioned a chromium-catalyzed 20,21 allylic defluorinative acylation reaction of trifluoromethyl-substituted olefins with acyl oxime esters as the acylating agent towards the synthesis of gem -difluoroalkenes containing a synthetically useful ketone group under mild reductive conditions (Scheme 1C).…”