SEARCH Articles Figures Tables 2,3,5,6,7,8-Hexahydro pyrimidine-1,3-dione 3- -4//-pyrido pyrimidine 3.4.6.7.8.9- Hexahydro-2//-pyrido Pyrido -dione Pyrido diones Pyrido pyrimidine-4,7-diones Pyrimidin-2,4-dione Pyrimidine diones Pyrimidine-2,6-dione