Radical Cyclization of N-Methacryloyl-2-arylbenzoimidazoles with Nitriles, Ketones, and tert-Butyl Nitrite under Mild Conditions

Abstract A method for radical cyclization of N-methacryloyl-2-arylbenzoimidazoles with nitriles, ketones, and tert-butyl nitrite (TBN) for the preparation of benzimidazo[2,1-a]isoquinolin-6(5H)-ones with the advantage of mild reaction conditions, excellent functional group compatibility, and broad substrate scope is reported. The present strategy has favorable characteristics: (1) the use of cheap metal catalysis; (2) N-radical-initiated cyclization of N-methacryloyl-2-arylbenzoimidazoles; and (3) rare example of radical C(sp3)–H functionalization in this cyclization.