Metal-free selective aryl C–H formylation co-controlled by 1,2,3-triazole and hydroxyl using DMSO as formyl source

Abstract

A facile and efficient method for direct C-H formylation of phenolated 1,4-disubstituted 1,2,3triazoles using DMSO as the formyl source has been developed. The reaction proceeded smoothly under metal-free conditions with good functional group tolerance and high selectivity co-controlled by the triazole ring and hydroxyl group.

Copper-Catalyzed Intramolecular C–H Alkoxylation of Diaryltriazoles: Synthesis of Tricyclic Triazole Benzoxazines

“…Transition-metal-catalyzed C–H functionalization is one of the most powerful methods to construct new C–X bonds on aromatic and heteroaromatic rings, and triazoles have been widely used as directing groups for C–H functionalization processes (Scheme , eq 1) . In contrast, there are few strategies for direct C–H activation on the triazole ring itself, examples being limited to Pd-catalyzed alkenylation and arylation at the C5 position (Scheme , eq 2), and to our previous report of an intramolecular silver-catalyzed C5-acyloxylation that affords fused triazole isochromenones (Scheme , eq 3)…”