Trifluoroacetic acid → (3aR,5R,6aR)-Methyl 2-benzyl-5-((tert-butoxycarbonyl)amino)octahydro-cyclopenta[c]pyrrole-3a-carboxylate

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Reaction Steps

To a solution of the product from Step B (5.51 g, 20 mmol) and N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine (6.4 mL, 24 mmol, Aldrich) in DCM (40 mL) was added 1M TFA in DCM (2.4 mL, 2.4 mmol) slowly. The resulting mixture was stirred at rt overnight and quenched by the addition of saturated aqueous NaHCO3 solution. The organic phase was washed with brine, dried over Na2SO4. Evaporation and purification by column chromatography (eluent: 10% EtOAc in hexanes to 20%) gave the desired isomer as a colorless gel. 1H-NMR (400 MHz, CDCl3) of the desired isomer: δ 1.38 (s, 9H), 1.66-1.86 (m, 2H), 1.86-1.96 (m, 1H), 1.96-2.08 (m, 1H), 2.29-2.63 (m, 3H), 2.71-2.93 (m, 2H), 3.43-3.56 (m, 2H), 3.58-3.74 (s, 3H), 4.08-4.29 (m, 1H), 4.78 (d, J=6.6 Hz, 1H), 7.11-7.31 (m, 5H). LC/MS: C24H28N2O4: m/z 375.2 (M+H).

Provenance & Evidence