(1,2,5)Thiadiazolo(3,4-d)pyrimidin-7(3H)-one (9CI) (1,2,5)Thiadiazolo(3,4-d)pyrimidin-7(6H)-one 6-Hydroxy-8-thiapurine 7598-41-6 BRN 1073875 NSC 406031