A Novel Synthesis of 1,2,4-Triazolopteridines

Reaction of 1,2-dihydro-2-thioxopteridin-4(3H)-one, 6,7-dimethyl-1,2-dihydro-2-thioxopteridin-4(3H)-one and 6,7-diphenyl-1,2-dihydro-2-thioxopteridin-4(3H)-one with hydrazonoyl halides affords the title compounds in good yields.