Radical Cascade Multicomponent Minisci Reactions with Diazo Compounds

Based on the strategy of polarity reversal in the generation of free radicals derived from diazo compounds, photocatalyzed multicomponent reactions (MCRs) of nitrogen aromatic heterocycles, alkenes, and diazo compounds form functionalized derivatives in good to high yields and exacting regioselectivities. The carbon radicals generated from the acceptor diazo compounds are electrophilic, and their selective additions with alkenes provide nucleophilic radicals, which enable the further rapid assembly with various heteroarenes. A delicate balance has been achieved between the activation of heteroarenes through protonation and the decomposition of diazo compounds by the same acid. This multicomponent Minisci reaction shows high functional group tolerance, especially in the incorporation of biologically active molecules. Detailed mechanistic studies that include photophysical measurements elaborate this radical cascade reaction. Furthermore, this transformation provides new opportunities for versatile reactions of diazo compounds in radical cascade multicomponent coupling reactions.