The potassium permanganate oxidation of 3-methylthio-5, 6-diphenyl-as-triazine in the presence of a phase-transfer catalyst afforded 3-methylsulfonyl-5, 6-diphenyl-as-triazine. The 3-sulfonyl-as-triazine readily reacted not only with active methylene compounds but also with methyl or methylene ketones under basic conditions, and 5, 6-diphenyl-as-triazines containing a functionalized carbon substituent at the 3-position were obtained. Similarly, 2-substituted 4, 6-dimethylpyrimidines were synthesized by the nucleophilic substitution of 4, 6-dimethyl-2-phenylsulfonylpyrimidine with various ketones.