Thieno[2,3-d]pyrimidin-4(3H)-one , its cas register number is 14080-50-3. It also can be called 1H-Thieno[2,3-d]pyrimidin-4-one ; 3H-Thieno[2,3-d]pyrimidin-4-one ;4-Hydroxythieno[2,3-d]pyrimidine ; Thieno[2,3-d]pyrimidin-4-ol .