Potassium Amide-Catalyzed Benzylic C-H Bond Addition of Alkylpyridines to Styrenes.

Abstract

The benzylic functionalization of alkylpyridines is an important pathway for pyridine derivatives synthesis. The reaction partners, however, were mostly limited to highly reactive polar electrophiles. Herein, we report a potassium amide-catalyzed selective benzylic C-H bond addition of alkylpyridines to styrenes. Potassium bis(trimethylsilyl)amide (KHMDS), a readily available Brønsted base, showed excellent catalytic activity and chemoselectivity. A series of alkylpyridine derivatives, including benzylic quaternary carbon substituted pyridines, were obtained in good to high yield. Preliminary mechanistic studies revealed that the deprotonation equilibrium is probably responsible for the excellent selectivity.