Catalytic Reductive Alkylation of Pyridine-Fused <i>N</i> -Heteroarenes Using Alkyl Formates as Transfer Hydroalkylation Reagents

This work reports ruthenium-catalyzed tandem reductive alkylation of <i>N</i>-heteroarenes to form saturated azacycles. In this reaction, alkyl formates are used as a new class of hydroalkylation reagents with LiI as a promoter. The reaction proceeds via C-O σ-bond cleavage of the formate scaffold, generating a hydride nucleophile and alkyl electrophile. The reaction features a broad substrate scope and produces CO₂ as the only byproduct, making the protocol atom efficient and environmentally friendly.