Chlorotrimethylsilane → 3-[1-(4-difluoromethoxy-benzenesulfonyl)-1H-indol-5-yl]azetidine-1-carboxylic acid tert-butyl ester

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Reaction Conditions

Reaction Steps

In an inert atmosphere, zinc dust (300 mg, 4.59 mmol) was vigorously stirred in dimethylacetamide (1.6 ml) and heated to 65° C. Subsequently, trimethylchlorosilane (70 μl, 0.57 mmol) and dibromoethane (50 μl, 0.57 mmol) were added to the reaction mixture, and the reaction mixture was stirred for another 30 minutes at 65° C. 3-Iodo-azetidine-1-carboxylic acid tert-butyl ester (1.0 g, 3.53 mmol) in dimethylacetamide (2 ml) was added dropwise to the above prepared solution at 65° C., and then the reaction mixture was allowed to cool to room temperature. 1-(4-Difluoromethoxy-benzenesulfonyl)-5-iodo-1H-indole (961 mg, 2.12 mmol) in dimethylacetamide (4 ml) was added to the reaction mixture. Subsequently, [1,1-bis(diphenylphosphino)ferrocene]-dichloropalladium(II)-dichlormethane (52.4 mg, 0.06 mmol) and copper(I)iodide (24.4 mg, 0.13 mmol) were added. The reaction mixture was heated to 80° C. for 1 hour, before it was cooled to room temperature and quenched with water (150 ml). Ammonium chloride (2 g) was added and the reaction mixture was extracted twice with diethylether (150 ml). The organic layer was dried over magnesium sulphate, filtered, and the solvent was evaporated under reduced pressure to give an oil (950 mg). The crude product was purified by silica gel chromatography with dichloromethane as eluent, yielding the purified product (553 mg, 52%). ESI-MS [m/z]: 423.05 [M-(C4H9)+H]+.

Provenance & Evidence