Ethyl Acetate → 5-Ethoxycarbonylamino-1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethylpyrrolo[2,3-b]indole

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Reaction Conditions

Reaction Steps

1,2,3,3a,8,8a-Hexahydro-5-nitro-1,3a,8-trimethylpyrrolo[2,3-b]indole (1.0 g) was dissolved in ethyl acetate (100 ml) and hydrogenated in a Parr apparatus at 45 psi using PtO2 (100 mg) as a catalyst. The reduction was complete within 2 hours. The reduction mixture was filtered directly into a nitrogen flushed flask. 4-Dimethylaminopyridine (50 mg) and triethylamine (0.14 g) were added, the mixture was cooled to 0° C. and a solution of ethylchloroformate (0.44 g) in ethyl acetate (70 ml) was added over a period of 1.5 hours. The mixture was washed with water (2×100 ml), dried (Na2SO4), concentrated and purified by flash chromatography on silica gel (eluting with 15% MeOH/EtOAc). The pure fractions were concentrated to give 5-ethoxycarbonylamino-1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethylpyrrolo[2,3-b]indole (0.6 g). The oxalate salt was prepared by dissolving the free base in ether (200 ml) and a minimum amount of MeOH (20 ml) and adding a solution of oxalic acid in ether.

Provenance & Evidence