Pyrimido(5,4-d)pyrimidine, 8-(phenylmethoxy)-2-(1-piperazinyl)-4-(4-thiomorpholinyl)-, S-oxide

4-[8-(Benzyloxy)-2-(piperazin-1-yl)pyrimido[5,4-d]pyrimidin-4-yl]-1lambda~4~-thiomorpholin-1-one