Dimethylformamide → (3aR,8aS)-7-Phenethyl-decahydro-pyrrolo[2,3-c]azepine

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Reaction Steps

To a solution of 6 in dichloromethane (25 mL) is added sequentially diisopropylethylamine (4.17 mL, 24 mmol), t-Boc-L-cyclohexylglycine (1.54 g, 6 mmol), and a solution of 0.45 M HOBt/HBTU in DMF (16 mL, 7.19 mmol). The mixture is stirred overnight at room temperature, then diluted with EtOAc (200 mL) and washed sequentially with 1 M aq. citric acid (50 mL), water (50 mL), aq. Sat. NaHCO3 (50 mL) and brine (2×50 mL). The organic layer is dried and concentrated under vacuum. The residue is purified by flash chromatography (silica gel; Hexane/EtOAc 1:9) to provide a yellow oil. The yellow oil is dissolved in dichloromethane (20 mL), TFA (10 mL) is added and the mixture is stirred at room temperature for 3 h. The mixture is concentrated and the residue is dissolved in dichloromethane (100 mL) and neutralized with saturated sodium bicarbonate. The solution is extracted with dichloromethane (3×50 mL). The organic extracts are combined, dried and concentrated under vacuum to provide 1.75 g (79% two steps) of the title compound which is used in next step without further purification or characterization.

Provenance & Evidence