Trimethylsilylacetylene → 4-(2-trimethylsilylethynyl)-3-(2,3,4,6-tetra-O-pivaloyl-beta-D-glucopyranosyloxy)-1H-indazole

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-bromo-3-(2,3,4,6-tetra-O-pivaloyl-β-D-glucopyranosyloxy)-1H-indazole (0.5 g) in triethylamine (5 mL) were added trimethylsilylacetylene (0.2 mL), tetrakis (triphenylphosphine) palladium (0) (81 mg) and copper (I) iodide (27 mg), and the mixture was stirred at 80° C. under an argon atmosphere overnight. The reaction mixture was cooled to room temperature and diluted with diethyl ether. The insoluble material was removed by filtration. The filtrate 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=4/1-3/1-2/1) to give 4-(2-trimethylsilylethynyl)-3-(2,3,4,6-tetra-O-pivaloyl-β-D-glucopyranosyloxy)-1H-indazole (0.4 g). This material was dissolved in tetrahydrofuran (5 mL). To the solution was added tetra(n-butyl) ammonium fluoride (0.15 g), and the mixture was stirred at room temperature for 1 hour. The reaction mixture was poured into 0.5 mol/L hydrochloric acid, and the resulting mixture was extracted with ethyl acetate. 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=2/1-1/1) to give the title compound (0.33 g).

Provenance & Evidence