Visible-light-absorbing C–N cross-coupling for the synthesis of hydrazones involving C(sp2)–H/C(sp3)–H functionalization

Abstract

An efficient C–N cross-coupling approach for the synthesis of hydrazones was developed through C(sp²)–H and C(sp³)–H functionalization of indole and methylarene under visible light irradiation using photocatalyst eosin Y, ethanol:water as a green solvent and atmospheric air as an oxidant. With the aid of eosin Y, the C–H bonds of indole and methylarenes were activated followed by coupling with arylhydrazines. The procedure was applied to a wide variety of substrates with good functional group compatibility, offering a creative way to make hydrazones from inexpensive and easily accessible raw materials. The absence of metals, low cost, environmental friendliness, green solvent, non-toxicity, ease of handling, and utilization of renewable energy sources like visible light are some of this method's primary advantages.