Regioselective Morita-Baylis-Hillman Reaction with N-Alkylpyridinium Salts as Electrophiles

Morita-Baylis-Hillman reaction employing N-alkylpyridinium salts as electrophiles has been developed. The reaction is promoted by DBU, which acts both as a catalyst activating the electron-poor olefin as well as a base. The transformation delivers a broad range of α-(hydropyridine)vinyl esters, ketones, and sulfones. The dearomatization of N-alkylquinolinium salts occurs regioselctively at the C-2 position, whereas N-alkylpyridinium salts undergo addition at the C-4 position.