Three-Component Reaction of 4-Methylpyridine with Alkyl Propiolates and Secondary Phosphine Chalcogenides

The reaction between 4-methylpyridine, alkyl propiolates, and secondary phosphine oxides proceeded as N -vinylation- C -phosphorylation with stereo- and regioselective formation of ( E )- N -ethenyl-C 2 - phosphoryl-1,2-dihydropyridines [when using bis(2-phenylethyl)phosphine oxide] or ( E )- N -ethenyl-C 4 - phosphoryl-1,4-dihydropyridines (when using diphenylphosphine oxide). The process occurred at 60–62°C within 3 h to give functional dihydropyridines in 40–82% yield. Under similar conditions, bis(2-phenylethyl) phosphine sulfide and selenide reacted with alkyl propiolates preferably by nucleophilic PH-monoaddition at the triple bond.