Sitagliptin phosphate monohydrate654671-77-9100 % similar Sitagliptin phosphate654671-78-095 % similar Sitagliptin486460-32-683 % similar 1-(3-(Trifluoromethyl)-5,6-dihydro(1,2,4)triazolo(4,3-a)pyrazin-7(8H)-yl)-4-(2,4,5-trifluorophenyl)butane-1,3-dione764667-65-458 % similar Sitagliptin enamine767340-03-454 % similar Sitagliptin deamino impurity 11253056-18-652 % similar Sitagliptin triazecine analog2088771-61-138 % similar