Cesium carbonate → Ethyl 6-{(E)-2-[3-(difluoromethoxy)-2-(2,2-dimethylpropoxy)phenyl]vinyl}imidazo[2,1-b][1,3]thiazole-5-carboxylate

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Reaction Conditions

Reaction Steps

To a stirred solution of Intermediate 6 (1.60 g, 4.209 mmol) in anhydrous N,N-dimethylformamide (10 mL) was added cesium carbonate (2.74 g, 8.418 mmol) followed by 1-bromo-2,2-dimethylpropane (1.60 mL, 12.629 mmol) at room temperature. The resulting suspension was stirred at 110° C. overnight under nitrogen atmosphere. The reaction mixture was cooled to room temperature and diluted with ethyl acetate (200 mL) and water (100 mL). The layers were separated. Aqueous layer was extracted with ethyl acetate (2×50 mL) and the combined organic layers were washed with brine (2×50 mL), dried (Na2SO4) and filtered. The filtrate was concentrated under reduced pressure. The residue obtained after the evaporation of the solvent was purified by silica gel column chromatography using 10% ethyl acetate in petroleum ether to obtain 1.20 g of the product as an off-white solid; 1H NMR (300 MHz, DMSO-d6) δ 1.07 (s, 9H), 1.39 (t, J=6.9 Hz, 3H), 3.57 (s, 2H), 4.35-4.42 (m, 2H), 7.18 (t, J=74.7 Hz, 1H), 7.20-7.25 (m, 2H), 7.47 (d, J=3.9 Hz, 1H), 7.52-7.58 (m, 1H), 7.73 (d, J=16.2 Hz, 1H), 7.90 (d, J=16.2 Hz, 1H), 8.10-8.16 (m, 1H); APCI-MS (m/z) 451.10 (MH)+.

Provenance & Evidence