Visible‐Light‐Mediated Photocatalyst‐Free Hydroacylation of Azodicarboxylic Acid Derivatives with 4‐Acyl‐1,4‐dihydropyridines

Abstract

Comprehensive SummaryA visible‐light‐enabled, photocatalyst‐free hydroacylation reaction of azodicarboxylic acid derivatives was described. This radical conjugate addition (RCA) protocol relied on the dual role of 4‐acyl‐1,4‐dihydropyridine (acyl‐DHP) reagents that besides being as radical reservoirs, they also enabled the conversion of radical adducts to anion intermediates via reduction. Under “catalyst‐oxidant‐additive free” conditions, a wide range of structurally different acyl hydrazide products were readily obtained in 56%—99% yields. The utility of this transformation was further demonstrated by the scale‐up synthesis and downstream derivatization.

Visible-Light-Induced Acylative Pyridylation of Styrenes

“…Recently, 4-alkyl/acyl-1,4-DHPs have gained great attention due to their nature as radical precursors . Our group has also developed their application in radical reactions with aromatic heterocycles, dehydroamino acids, and azodicarboxylic acid . The pioneering work has been developed by the Melchiorre group, who has achieved a bimolecular coupling of 4-benzyl-1,4-DHPs with cyanopyridines under high-power single-light-emitting diode irradiation at 405 nm .…”