Visible Light-Induced Decomposition of Acyl Peroxides Using Isocyanides: Synthesis of Heteroarenes by Radical Cascade Cyclization

Visible light-mediated facile synthesis of hetero-arenes, namely, isoquinolines, benzothiazoles, and quinazolines, is demonstrated by employing isocyanides and inexpensive acyl peroxides. It is shown for the first time that singlet-excited isocyanides decompose acyl peroxides into aryl/alkyl radicals. The latter attack isocyanides, yielding imidoyl radicals that subsequently cyclize to afford heteroarene products. The protocol involving radical cascade reactions obviates the requirement of any external photocatalyst, oxidant, additive, and base.

Automated summary

This study demonstrates a visible light-mediated synthesis of hetero-arenes (isoquinolines, benzothiazoles, and quinazolines) through the use of isocyanides and inexpensive acyl peroxides. It is the first time that singlet-excited isocyanides have been shown to decompose acyl peroxides into aryl/alkyl radicals. The resulting radicals attack isocyanides, leading to the formation of imidoyl radicals which subsequently cyclize to generate heteroarene products. The protocol eliminates the need for external photocatalysts, oxidants, additives, and bases.