Trifluoroacetic acid → 2-(4-Bromo-2-fluorobenzyl)-4-(-)-menthyloxycarbonyl-1,3-dioxo-1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazine-4-acetic acid

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Reaction Steps

A mixture of 2-(4-bromo-2-fluorobenzyl)-4-(-)-menthyloxycarbonyl-1,3-dioxo-1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazine-4-acetic acid tert-butyl ester (Diastereomer A) (30.0 g) and trifluoroacetic acid (112.5 g, 76.0 ml) in anhydrous dichloromethane (120 ml) was refluxed for 1.5 hours and concentrated under reduced pressure. The residue was dissolved in a mixture of acetonitrile and toluene. The resulting solution was evaporated under reduced pressure to give the title compound (Diastereomer A) (27.3 g, quantitative) as a brown oil.

Provenance & Evidence