A mechanistic insight into the chemoselectivity of the reaction between 3-phenyl-2-propynenitrile, secondary phosphine oxides and pyridinoids

Reactions between 3-phenyl-2-propynenitrile, secondary phosphine oxides and pyridinoids have been implemented and studied. Pyridine and isoquinoline react with propynenitrile and phosphine oxides at room temperature according to the N-vinylation/C-phosphorylation scheme to afford (Z)-N-(2-cyano-1-phenyl)ethenyl phosphoryl-1,4-dihydropyridines or -1,2-dihydroiso quinolines. In the case of pyridine on heating ($\mathrm{80-85^{\circ}C}$), the reaction gives 4-phosphorylpyridines ($\mathrm{S_N^H{Ar}}$ reaction) and 3-phenyl-acrylonitrile oligomers.