Synthesis of novel 5-phenylselenenyl pyrimidine analogs

5-Phenylselenenyl-4-substituted-2-benzylthiopyrimidine analogs were prepared efficiently in four steps. Reaction of 2-thiouracil with benzyl chloride in presence of base furnishes 2-benzylthio uracil, which on reaction with phenylselenenyl chloride in pyridine under anhydrous conditions yielded 5-phenylselenenyl-2-benzylthio uracil. Chlorination of 5-phenylselenenyl-2-benzylthio uracil with excess POCl 3 under reflux furnishes 5-phenylselenenyl-4-chloro-2-benzylthiopyrimidine. Aromatic nucleophilic substitution reaction of 5-phenylselenenyl-4-chloro-2-benzylthiopyrimidine with oxygen nucleophiles like sodium ethoxide, sodium benzylate and nitrogen nucleophiles like aliphatic primary amines, substituted aromatic primary amines furnished the target compounds in 48-80% yield. 5-Phenylselenenyl-4-(substitutedbenzylidenehydrazino)-2-benzylthiopyrimidines were prepared in 60-75% yield, by the reaction of 5-phenylselenenyl-4-(hydrazino)-2-benzylthiopyrimidine with various aromatic aldehydes.