Electrochemically enabled synthesis of sulfide imidazopyridines via a radical cyclization cascade†
Owing to the inert nature of the pyridine ring and high activity of iminyl radicals, the reaction between pyridine and iminyl radicals remains a significant challenge. In this paper, we report the synthesis of sulfide imidazo[1,2-a]pyridines from vinyl azides, thiophenols, and pyridines via a radical [3 + 2] cycloaddition. Promoting inert pyridine and highly active iminyl radicals to participate in this intermolecular cycloaddition process is the striking feature of this protocol. The excellent antitumor activity of the prepared sulfide imidazopyridine scaffold demonstrated the synthetic utility of the developed synthetic protocol.