Methanesulfonic Acid → 8a-Pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-tetrahydro-imidazo[1,5-a]pyrazine-1,3-dione

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Reaction Steps

To a solution of 1,3-dioxo-8a-pyridin-2-ylmethyl-2-(2,2,2-trifluoro-ethyl)-hexahydro-imidazo[1,5-a]pyrazine-7-carboxylic acid tert-butyl ester (prepared as described in Step 5, 1.89 g, 4.4 mmol) in CH2Cl2 (20 mL) was added MeSO3H (2.14 g, 22 mmol). The reaction mixture was stirred at room temperature for one hour. Triethylamine (2.45 g, 24.2 mmol) was added to the solution. The organic layer was washed with 100 mL of H2O, brine, dried over MgSO4, and concentrated to give a 1.4 g of the title compound as a yellow oil (97%). The oil solidified upon granulation in hexane or upon cooling.

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