... 3-(trifluoromethyl)-5,6,7,8-tetrahydro-1,2,4-triazolo[4,3-a]pyrazin-7-yl]-4-(2, ... -one; 1,2,4-Triazolo(4,3-a)pyrazine, 7-((3R)-3-amino-1-oxo-4-(2,4 ... ,5-trifluorophenyl)butyl)-5,6,7,8-tetrahydor-3-(trifluoromethyl)-; Sitagliptin Intermediate; (2R)- ... 6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl) ... 6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-4-(2,4,5-trifluorophenyl) ...