Hydrochloric Acid → 3-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyloxy)-4-{[4-(4-carboxybut-1-ynyl)phenyl]methyl}-5-isopropyl-1H-pyrazole

Participants

Reaction Steps

A mixture of 3-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyloxy)-4-[(4-iodophenyl)methyl]-5-isopropyl-1H-pyrazole (0.43 g), 4-pentynoic acid (94 mg), tetrakis(triphenylphosphine)palladium(0) (37 mg), copper(I)iodide (12 mg) and tiethylamine (0.45 mL) in tetrahydrofuran (5 mL) was stirred at room temperature under an argon atmosphere overnight. 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=1/2-ethyl acetate) to give 3-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyloxy)-4-{[4-(4-carboxybut-1-ynyl)phenyl]methyl}-5-isopropyl-1H-pyrazole (0.37 g). This material was dissolved in N,N-dimethylformamide (6 mL). To the solution were added benzyl 2-amino-2-methylpropionate hydrochloride (0.15 g), 1-hydroxybenzotriazole (86 mg), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (0.22 g) and triethylamine (0.32 mL), and the mixture was stirred at room temperature overnight. 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, a saturated aqueous sodium hydrogen carbonate solution and brine successively, 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: dichloromethane/methanol=20/1) to give 3-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyloxy)-4-[(4-{4-[1-benzyloxycarbonyl-1-(methyl)-ethylcarbamoyl]but-1-ynyl}phenyl)methyl]-5-isopropyl-1H-pyrazole (0.36 g). This material was dissolved in methanol (5 mL). To the solution was added 10% palladium-carbon powder (50 mg), and the mixture was stirred at room temperature under a hydrogen atmosphere for 2 hours. The insoluble material was removed by filtration, and the solvent of the filtrate was removed under reduced pressure to give the title compound (0.31 g).

Provenance & Evidence