An efficient route to 4-aryl-5-pyrimidinylimidazoles via sequential functionalization of 2,4-dichloropyrimidine

Starting from 2,4-dichloropyrimidine, a concise synthetic route to medicinally important 4-aryl-5-pyrimidinylimidazoles is described. Sequential substitution of the 4- and 2-chloro groups using a regioselective Sonogashira coupling, followed by nucleophilic substitution, led to pyrimidinylalkyne derivatives, which were then oxidized to their corresponding 1,2-diketones. These 1,2-diketones, on cyclocondensation with ammonium acetate and an aldehyde, furnished the desired pyrimidinyl imidazoles in good overall yields.