Regioselective and site-divergent synthesis of tetrahydropyridines by controlled reductive-oxidative dearomative hydroarylation of pyridinium salts.

Abstract

Tetrahydropyridine skeletons serve as ubiquitous structural motifs which are predominant in natural products, bioactive and drug molecules. Thus, the development of efficient and general synthetic methods for the synthesis of tetrahydropyridine frameworks with different substitutions has attracted great attention from the community. Moreover, the control of regioselectivity and site-divergency remains an unmet challenge. Herein, we report a regioselective and site-divergent reductive hydroarylation of pyridinium salts with aryl nucleophiles, enabling direct access to diverse tetrahydropyridine derivatives with aryl substitution at different positions under mild conditions. Mechanistic studies support that the reaction underwent a CoH-mediated double-reduction process of pyridinium salts.