Well‐Defined Ni−SNS Complex Catalysed Borrowing Hydrogenative α‐Alkylation of Ketones and Dehydrogenative Synthesis of Quinolines

Abstract The “borrowing hydrogen” (BH) method for C‐alkylation reactions using alcohol as alkylating agents is an important synthetic transformation. In this respect, designing cheap and bench stable earth abundant metal catalyst for borrowing hydrogen transformation is a key challenge to be witnessed. Herein we have presented a synthesis of non‐phosphine, easily accessible and bench stable SNS−Ni complexes. The Ni‐catalyst was successfully applied for the C‐alkylation of ketone enolates to α‐alkylated ketones. Primary alcohol with different functional groups and various heteroaromatic alcohols are well tolerated. The present catalyst system was efficiently applied to gram scale synthesis and also the green chemistry metrics of the reaction were calculated. The present protocol was also extended successfully for the synthesis of biologically important quinoline moieties. Finally, various control experiments and deuterium labelled experiments suggest that the reaction proceeds via borrowing hydrogen pathway. magnified image