Chromium-catalyzed reductive alkylation of <i>N</i> -heteroarenes using alkyl formates as transfer hydroalkylation reagents

Alkyl formates are employed as transfer hydroalkylation reagents in the reductive alkylation of <i>N</i>-heteroarenes to saturated azacycles. This is achieved using a well-defined chromium catalyst and LiI as a promoter <i>via</i> the cleavage of the C-O σ-bond of the formate, generating a hydride nucleophile and an alkyl electrophile. The reaction produces volatile CO₂ as the only byproduct, making the method atom-efficient and environmentally friendly.