Trifluoroacetic acid → (3aR,6aR)-Hexahydro-pyrrolo[3,4-b]pyrrole-5-carboxylic acid benzyl ester

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Reaction Steps

The product of Example 1A ((3aR,6aR)-hexahydro-pyrrolo[3,4-b]pyrrole-1,5-dicarboxylic acid 5-benzyl ester 1-tert-butyl ester) (4.5 g, 12.5 mmole), was stirred with a mixture of dichloromethane and trifluoroacetic acid (15 ml/15 ml) for 2 hours. The solvent was removed under reduced pressure, and the residue was basified with saturated sodium bicarbonate, then extracted with dichloromethane (3×). The combined organic layers were washed with brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography (0.6% ammonium hydroxide and 6% methanol in dichloromethane) to provide the title compound. 1H NMR (CDCl3) δ ppm 7.28-7.40 (m, 5H) 5.12 (s, 2H) 3.74-3.87 (m, 1H) 3.53-3.71 (m, 2H) 3.36-3.48 (m, 1H) 3.18-3.32 (m, 1H) 3.01-3.13 (m, 1H) 2.88-3.01 (m, 1H) 2.70-2.83 (m, 1H) 1.87-2.03 (m, 1H) 1.58-1.76 (m, 1H). MS: (M+H)+=247.

Provenance & Evidence