Cesium carbonate → 1-(2,4-difluorophenyl)-1H-imidazole-4-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

To 1H-imidazole-4-carbaldehyde (3.01 g, 31.3 mmol), 2,4-difluoro-1-iodobenzene (1.008 g, 4.20 mmol), Cs2CO3 (2.281 g, 7.00 mmol) in DMF (50 mL) was added copper(I) iodide (0.033 g, 0.175 mmol) and (1R,2R)—N1,N2-dimethylcyclohexane-1,2-diamine (0.100 g, 0.700 mmol). The reaction was heated to 110° C. for 18 hours. The reaction mixture was then cooled to room temperature and filtered, and washed with EtOAc (100 mL). The organic was washed with water (2×30 mL) and brine (30 mL), dried (Na2SO4) and concentrated. The residue was purified by silica gel chromotography to give 1-(2,4-difluorophenyl)-1H-imidazole-4-carbaldehyde (651 mg), to which was added (S)-2-methylpropane-2-sulfinamide (0.424 g, 3.5 mmol), CuSO4 (0.798 g, 5 mmol) and DCE (10 mL). The reaction was heated to 65° C. for 18 hours. The reaction was cooled to rt, filtered and concentrated to give (S,E)-N-((1-(2,4-difluorophenyl)-1H-imidazol-4-yl)methylene)-2-methylpropane-2-sulfinamide, to which was added DCM (20 mL). The reaction mixture was cooled to −70° C. and methylmagnesium bromide (1.667 ml, 5 mmol) was added dropwise to the solution. The reaction was stirred for two hours and the cold bath was then removed, and the reaction was allowed to warm to rt and stir for 30 minutes. The reaction was cooled to 0° C. and HCl (1M) was added cautiously to quench until aqueous pH=8. The phases were separated and the aqueous layer was extracted with DCM (2×30 mL). Combined organic was dried (Na2SO4) and concentrated to give (S)—N—((S)-1-(1-(2,4-difluorophenyl)-1H-imidazol-4-yl)ethyl)-2-methylpropane-2-sulfinamide (230 mg), which was then dissolved in MeOH (5 mL) and HCl (0.5 mL, 4M) was added. The reaction was stirred for one hour and concentrated to give product (212 mg). LCMS m/z 224.1 (M+H)+; Rt-0.39 min.

Provenance & Evidence