(2Z)-4-Oxo-4-[3-(trifluoromethyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazine-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-one

Chemical Properties

Brown Oil

Uses

4-Oxo-4-[3-(trifluoromethyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-one is a Sitagliptin intermediate.

Synthesis

Potassium tert-butoxide (2.24 g, 20 mmol) was dissolved in 40 mL of tetrahydrofuran in a 100 mL single-necked flask and stirred for 1 min at room temperature. Subsequently, ethyl 3-oxo-4-(2,4,5-trifluorophenyl)butanoate (1.91 g, 10 mmol) and 3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine (2.60 g, 10 mmol) were added sequentially and stirring was continued for 60 min at room temperature. After completion of the reaction, the tetrahydrofuran was removed by distillation under reduced pressure. The residue was extracted by adding 50 mL of water and 50 mL of dichloromethane to the residue. The organic phase was separated and dried over anhydrous sodium sulfate, followed by evaporation of the solvent. The crude product was recrystallized by dichloromethane and cyclohexane to give 3.33 g of 1-(3-trifluoromethyl-5,6-dihydro-8H-[1,2,4]triazol-[4,3-A]pyrazine-7(8H)-yl)-4-(2,4,5-trifluorophenyl)-1,3-butanedione in 82% yield and 99% purity.

References

[1] Patent: CN108178761, 2018, A. Location in patent: Paragraph 0032; 0038; 0039; 0061-0066