Facile synthesis of 4-substituted pyridines using grignard reagents

N-t-Butyldimethylsilylpyridinium triflate $\text{2}$ reacted with Grignard reagents at 4-position with almost complete regioselectivity ($\text{>}$99%) to afford the corresponding 1,4-dihydropyridine derivatives ($\text{3}$), which are easily oxidized by oxygen to give 4-substituted pyridines ($\text{4}$: 58 – 70%).