Organoselenium-Catalyzed Regioselective C-H Pyridination of 1,3-Dienes and Alkenes.

An efficient approach for organoselenium-catalyzed regioselective C-H pyridination of 1,3-dienes to form pyridinium salts has been developed. This method was also successfully applied to direct C-H pyridination of alkenes. Fluoropyridinium reagents, or initially loaded pyridine derivatives, acted as pyridine sources in the pyridination reactions. The obtained pyridinium salts could be further converted under different conditions. This work is the first example of catalytic C-2 direct C-H functionalization of 1,3-dienes and the first case of organoselenium-catalyzed C-H pyridination.