A Filtration‐Assisted Tandem Strategy for Selective Mono‐α‐Alkylation of Ketones via Electrochemical Reduction

ABSTRACT A sustainable tandem strategy was developed for the selective mono‐ α ‐alkylation of ketones using aldehydes as alkylating agents. The reaction proceeds via aldol condensation to form a chalcone intermediate, which is isolated by simple filtration to avoid over‐alkylation, followed by electrochemical reduction of the C═C bonds under mild conditions using renewable electricity and formamide as a green proton donor. Notably, tetrabutylammonium acetate is found to facilitate the anodic reaction through the formation of a hydrogen bond between the acetate anion and the N─H moiety of formamide, thereby enhancing the reaction efficiency. On the other hand, the mother liquor from the first step can be recycled for multiple rounds of chalcones synthesis in efficiency. Mechanistic studies, including cyclic voltammetry, UV–vis spectroscopy, and control experiments, support a reaction pathway involving the reduction of chalcones followed by proton abstraction from activated formamide. This method avoids the use of alkyl halides and eliminates over‐alkylation issues, and offers a practical and environmentally friendly approach for the synthesis of 1,4‐diaryl ketones.