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

Participants

Reaction Steps

To a solution of (3aSR, 6aRS)-3-methyl-2-oxo-hexahydro-cyclopentaimidazole-1-carboxylic acid tert-butyl ester (Example 106, step 2) (1.99 g, 8.28 mmol) in 30 ml of dichloromethane was added trifluoroacetic acid (7.55 g, 5.1 ml, 66.3 mmol, 8 equiv.) and the yellow solution was stirred at for 5 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 1.07 g of an off-white solid, which was taken up in cold ethyl acetate and filtered to yield the title compound (822 mg, 71%) as a crystalline white solid which was directly used in the next step without further characterisation.

Provenance & Evidence