Transition-Metal-Catalyzed C(sp3)–H Alkylation of Methyl Heteroarenes with Alcohols

Transition-metal-catalyzed C(sp3)-H bond functionalization is a useful transformation for the construction of C–C bonds. A versatile and easy-to-perform protocol in this respect is the C-alkylation of methyl heteroarenes with alcohols using auto-transfer hydrogenative (ATH) reactions. Various transition metal catalysts based on Ir, Pt, Ru, Ni, Co, Fe and Mn have been employed for the construction of chain-elongated alkyl-substituted heterocyclic compounds using this chemistry. Water is the only byproduct and the starting alcohols are less toxic, readily available, more easily handled and more atom-economical substrates than their halogen counterparts. This review details recent advances in this synthetic methodology, describing the scope, reaction mechanism, chemo-selectivity and applications.