Pyridine → 2-Bromoethyl 2,2-dimethylpropanoate

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Reaction Steps

To a solution of 2-bromoethanol (0.36 mL) and pyridine (0.61 mL) in tetrahydrofuran (5 mL) was added pivaloyl chloride (0.62 mL) under ice-cooling, and the mixture was stirred at room temperature overnight. The reaction mixture was poured into a saturated aqueous ammonium chloride solution, and the resulting mixture was extracted with diethyl ether. The extract was washed with water, a saturated aqueous sodium hydrogen carbonate solution and brine, and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure to give (2-bromoethyl) pivalate (1.04 g). A mixture of 4-bromo-3-(2,3,4,6-tetra-O-pivaloyl-β-D-glucopyranosyloxy)-1H-indazole (0.93 g), (2-bromoethyl)pivalate (0.82 g), cesium carbonate (1.27 g) and sodium iodide (0.2 g) in N,N-dimethylformamide (10 mL) was stirred at 65° C. for 6 hours. The reaction mixture was poured into water, and the resulting mixture was extracted with diethyl ether. The extract was washed with water and brine, and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure, and the residue was purified by column chromatography on silica gel (eluent: n-hexane/ethyl acetate=4/1−3/1) to give the title compound (0.73 g).

Provenance & Evidence