Trifluoroacetic acid (0.36 mL) was added to a stirred mixture of 2-phenoxymethyl-6,7-dihydro-pyrazolo[1,5-a]pyrazine (0.43 g, 1.87 mmol) and potassium hydrogen fluoride (0.18 g, 2.34 mmol) in CH3CN (3.7 mL) and DMF (0.4 mL) at 0° C. The mixture was stirred at 0° C. for 5 minutes. Then Ruppert's reagent (0.83 mL, 5.61 mmol) was added and the mixture was stirred at room temperature for 16 hours. The mixture was treated with a saturated solution of Na2CO3, diluted with water and extracted with DCM. The organic layer was separated, dried (Na2SO4), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; 7N solution of ammonia in methanol in DCM 0/100 to 30/70). The desired fractions were collected and the solvents evaporated in vacuo to yield rac-2-phenoxymethyl-4-trifluoromethyl-4,5,6,7-tetrahydro-pyrazolo[1,5-a]pyrazine (350 mg, 63% yield) as a yellow oil.
