反应详情

To a solution of 3-butyl-5-([E]-styryl)-isoxazole-4-carboxylic acid (7.0 g, 25.8 mmol) and triethylamine (3.8 mL, 27.0 mmol) in THF (30 mL) was added at 0° C. ethyl chloroformate (2.6 mL, 27.0 mmol). After 1 h the triethylamine hydrochloride salt was filtered off and washed with a small amount of THF. The filtrate was concentrated, the residue taken up in ethanol (70 mL) and added to a solution of sodium borohydride (2.4 g, 63.4 mmol) in water (35 mL) at 0° C. After stirring at room temperature for 2.5 days, the reaction was quenched with aqueous sodium hydroxide (1 M, 40 mL) and extracted twice with tert-butylmethylether. The combined phases were washed with brine, dried over sodium sulfate and filtered. The filtrate was concentrated to a yellow oil and purified by flash chromatography (silica, dichloromethane:methanol 100:0 to 97:3) to afford the title compound (6.9 g, 98%) as an orange oil. MS: m/e=258.1 [M+H]+.

1. filtrationAfter 1 h the triethylamine hydrochloride salt was filtered off
2. washwashed with a small amount of THF
3. concentrationThe filtrate was concentrated
4. customthe reaction was quenched with aqueous sodium hydroxide (1 M, 40 mL)
5. extractionextracted twice with tert-butylmethylether
6. washThe combined phases were washed with brine
7. dry with materialdried over sodium sulfate
8. filtrationfiltered
9. concentrationThe filtrate was concentrated to a yellow oil
10. custompurified by flash chromatography (silica, dichloromethane:methanol 100:0 to 97:3)