2-bromo-5-(1,3-dimethyl-1H-pyrazol-4-yl)-7-(trifluoromethyl)-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine → (5R,7S)-2-bromo-5-(1,3-dimethyl-1H-pyrazol-4-yl)-7-(trifluoromethyl)-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine

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Reaction Steps

The racemic 2-bromo-5-(1,3-dimethyl-1H-pyrazol-4-yl)-7-(trifluoromethyl)-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine (1.5 g, 4.1 mmol, Preparation 8) was dissolved in methanol (35 mL) and the cloudy solution was gently warmed providing a clear solution. The solution was then filtered through a medium porosity Buchner funnel. The clear filtrate was directly used for chiral HPLC purification. 1 mL of this solution was loaded onto a 2.1 cm×25 cm Chiralcel OD column and eluted with a mobile phase comprising of isopropyl alcohol and methanol (1:1 ratio) at a flow rate of 15 mL/min. The two (R and S) enantiomers were collected separately. 27 such injections were carried out and the pooled fractions of pure (R and S) enantiomers were concentrated under reduced pressure. The title compound was isolated as a white powder (0.71 g, 1.95 mmols, >95% ee).

Provenance & Evidence