反应详情

A mixture of 4-butyl-5-phenylisoxazole-3-carboxylic acid, lithium salt (0.132 g, 0.523 mmol), (Z)-tert-butyl 1-(4-(N′-hydroxycarbamimidoyl)benzyl)azetidine-3-carboxylate (Int.1, 0.160 g, 0.523 mmol), N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine hydrochloride (0.100 g, 0.523 mmol), and HOBt (0.080 g, 0.523 mmol) in N,N-dimethylformamide (4 mL) was stirred at room temperature for 60 min and then heated at 60° C. overnight. The solvent was removed under reduced pressure. The residue was purified by flash silica gel chromatography eluting with 1% methanol in dichloromethane to give tert-butyl 1-(4-(5-(4-butyl-5-phenylisoxazol-3-yl)-1,2,4-oxadiazol-3-yl)benzyl)azetidine-3-carboxylate (0.156 g) as a pale yellow solid. The ester intermediate was >99% pure by HPLC with a ret. time=3.40 min.−Column. CHROMOLITH® SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.1% TFA; Solvent B=90% MeOH, 10% H2O, 0.1% TFA. LC/MS M+1=515.0.

1. temperatureheated at 60° C. overnight
2. customThe solvent was removed under reduced pressure
3. customThe residue was purified by flash silica gel chromatography
4. washeluting with 1% methanol in dichloromethane