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The present work documents an organophotoredox‐mediated formal [3+2]‐cycloaddition of 2H‐azirines with aryl diazonium tetrafluoroborate salts to furnish 1,3,5‐trisubstituted 1,2,4‐triazoles. The reaction furnishes a regioisomeric mixture of 1,2,4‐triazoles in case of unsymmetrically substituted azirines. It is noteworthy that aryl radical generation from diazonium salt under visible light photoredox conditions could be successfully avoided by carefully selecting the reaction conditions. [ABSTRACT FROM AUTHOR]

An efficient regioselective synthesis of tetrasubstituted 3‐imidazolines under organo‐photocatalytic conditions has been developed through formal [3+2]‐cycloaddition between 2H‐azirines and N‐tosyl benzylidene imines. The products were isolated in high yields and as a separable mixture of diastereoisomers in most of the cases. The mild reaction conditions employing an organic dye as photocatalyst, excellent functional group tolerance, and high regioselectivity are notable features of the current protocol. [ABSTRACT FROM AUTHOR]