1-Piperazinecarboxaldehyde, 4-(8-((phenylmethyl)thio)-4-(4-thiomorpholinyl)pyrimido(5,4-d)pyrimidin-2-yl)-, S-oxide 77777-16-3 8-Benzylthio-2-(N-formylpiperazino)-4-(1-oxidothiomorpholino)-pyrimido(5,4-d)pyrimidine