An efficient synthesis of novel 3, 5-difluoropyridine-4-carboxaldehyde using N-fluoro- benzenesulfonimide (NSFi) is described. Difluorination was achieved through the reaction of 3, 5-dihalo-1, 3-dioxolane pyridine with n-butyllithium followed by N- fluorobenzenesulfonimide at− 120° C in good to high yields. Maintaining the low temperature during the transmetallation was found to be critical for the selective formation ...
