Hydrochloric Acid → 5-(2,5-difluorobenzyl)-N-(4-(triethylsilyl)but-3-ynyl)isoxazole-3-carboxamide

Participants

Reaction Conditions

Reaction Steps

A mixture of (4-azidobut-1-ynyl)triethylsilane (1.00; 4.78 mmol) and triphenylphosphine (1.88 g; 7.16 mmol) in methanol (10 mL) was stirred at 60° C. for two hours. HCl (4N in dioxane was added to resulting solution and the mixture was concentrated under reduced pressure. The residue was dissolved in dichloromethane. HATU (2.18 g; 5.73 mmol), N,N-diisopropylethylamine (2.06 mL; 4.78 mmol) and 5-(2,5-difluorobenzyl)isoxazole-3-carboxylic acid intermediate 74 (1.26 g; 5.25 mmol) were added and the resulting mixture was stirred at room temperature overnight and diluted in dichloromethane, washed with sodium hydrogen sulphate, sodium carbonate and brine and concentrated under reduced pressure. The crude mixture was purified by flash chromatography on silica (eluent 1 to 60% ethyl acetate in heptane) to yield 0.901 g (47%) of 5-(2,5-difluorobenzyl)-N-(4-(triethylsilyl)but-3-ynyl)isoxazole-3-carboxamide as a yellow oil.

Provenance & Evidence