Trifluoroacetic acid → trans-[2-(3-Ethyl-pyrrol-1-yl)-cydohexyl]-carbamic acid tert-butyl ester

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Reaction Steps

Methylmagnesium chloride solution (3 M in tetrahydrofuran, 0.23 ml, 0.68 mmol) was added at −78° C. to a solution of trans-[2-(3-formyl-pyrrol-1-yl)-cyclohexyl]-carbamic acid tert-butyl ester (example 26a, 100 mg, 0.34 mmol) in tetrahydrofuran (2 ml), then after 3.5 h the reaction was quenched by addition of saturated aqueous ammonium chloride solution and extracted with dichloromethane. The organic layer was washed with brine, dried (MgSO4), and evaporated. This crude material (103 mg) was dissolved in dichloromethane (2 ml) and treated with triethylsilane (58 mg, 0.50 mmol) and trifluoroacetic acid (190 mg, 1.67 mmol). The reaction mixture was allowed to reach 0° C. over 3 h, then evaporated and the residue chromatographed (SiO2, heptane-ethyl acetate gradient) to afford the title compound (27 mg, 28%). Yellow solid, MS (ISP) 293.2 (M+H)+.

Provenance & Evidence