1,1'-Carbonyldiimidazole → ethyl 2-((1R)-1-{2-[(benzyloxy)amino]-2-oxoethyl}-4-cyclohexylbutyl)-1,3-oxazole-4-carboxylate

Participants

Reaction Steps

A mixture of (3R)-6-cyclohexyl-3-[4-(ethoxycarbonyl)-1,3-oxazol-2-yl]hexanoic acid trifluoroacetate (Preparation 63) (1.66 g, 3.68 mmol), 1,1′-carbonyldiimidazole (0.80 g, 4.93 mmol), O-benzylhydroxylamine hydrochloride (1.57 g, 9.84 mmol) and N,N-diisopropylethylamine (1.71 ml, 9.82 mmol) in anhydrous tetrahydrofuran (10 ml) was stirred at room temperature for 72 hours. The mixture was diluted with ethyl acetate (50 ml) and washed sequentially with a saturated solution of sodium hydrogen carbonate, aqueous citric acid solution (10% w/v) and brine, dried over anhydrous magnesium sulphate, filtered and the solvent removed under reduced pressure. The residue was purified by column chromatography on silica gel eluting with dichloromethane:methanol (98:2) then further purified by column chromatography on silica gel eluting with ethyl acetate:pentane (50:50) to afford the title compound as an orange oil (1.41 g)

Provenance & Evidence