Cesium carbonate → 4-[4-Fluoro-3-(1-methyl-1H-benzoimidazol-2-yl)-phenyl]-piperazine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

2-(5-Bromo-2-fluoro-phenyl)-1-methyl-1H-benzoimidazole (2.10 g, 6.9 mmol), piperazine-1-carboxylic acid tert-butyl ester (1.16 g, 8.3 mmol), cesium carbonate (3.14 g, 9.6 mmol) rac-2,2′ bis(diphenylphosphino)-1,1′-binaphtyl (BINAP) (0.17 g, 0.28 mmol) and tris-(dibenzilideneacetone)dipalladium(0) (0.06 g, 0.07 mmol) were placed in a Schlenk tube and purged by repeated nitrogen/vacuum cycles for 10 minutes. Dry toluene (13 mL) was added and the reaction was stirred at 85° C. for 24 h. Reaction was cooled to room temperature, diluted with AcOEt (20 mL) and washed with water (10 mL). The organic layer was dried over Na2SO4 and concentrated under reduced pressure. The crude reaction mixture was purified by flash chromatography (eluent: cyclohexane:AcOEt gradient from 100% cyclohexane to cyclohexane 2:AcOEt 1) to afford 1.14 g of the starting material and 0.70 g of the title compound (54%).

Provenance & Evidence