Site-selectivity in the reaction of 3-substituted pyridine 1-oxide with phosphoryl chloride was investigated. When a strongly electron-withdrawing group (e.g. CN, CONRR', COOR, or NO₂) was substituted at the 3-position, the reaction of 3-substituted pyridine 1-oxides with phosphoryl chloride yielded 3-substituted 2-chloropyridines as the main products.