Trifluoroacetic acid → (rac)-(3aRS, 6aSR)-1-Ethyl-hexahydro-cyclopentaimidazol-2-one

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Reaction Steps

To a solution of (3aSR,6aRS)-3-methyl-2-oxo-hexahydro-cyclopentaimidazole-1-carboxylic acid tert-butyl ester (Example 1, step 2) (1.60 g, 6.29 mmol) in 15 ml of dichloromethane was added trifluoroacetic acid (5.74 g, 3.9 ml, 50.3 mmol, 8 equiv.) and the yellow solution was stirred for 15 h at room temperature. The reaction mixture was quenched by addition of saturated sodium bicarbonate solution and the pH of the aqueous phase was set to 9. After workup with dichloromethane/water, the organic phases were dried, filtered and concentrated in vaccuo to yield 0.801 g of a yellow oil, which directly used in the next step without further characterization.

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