Photoinduced alkylation of pyrazolones via β-scission of unstrained aliphatic alcohol derivatives

Abstract

Alcohols play a pervasive role in the realm of chemistry, constituting inherent functional groups in numerous natural products and bioactive molecules. In this study, we introduce an efficient radical approach for the activation and transformation of unstrained aliphatic alcohols through the β-scission of alkoxyl radicals under mild conditions, avoiding the need for metals, photocatalysts, and other additives. Additionally, we showcase the utility of this method in three-component cascade radical coupling reactions involving 1,3-butadiene or 1,3-enyne, respectively. Mechanistic studies reveal the excited state of the pyrazolone enolate as a key intermediate with dual functions as a radical precursor and an efficient reductant, leading to the formation of a radical pair in the reaction.