[CH2:1]([C:5]1[C:9]([C:10](O)=[O:11])=[C:8](/[CH:13]=[CH:14]/[C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)[O:7][N:6]=1)[CH2:2][CH2:3][CH3:4].C(N(CC)CC)C.ClC(OCC)=O.[BH4-].[Na+]>C1COCC1.O>[CH2:1]([C:5]1[C:9]([CH2:10][OH:11])=[C:8](/[CH:13]=[CH:14]/[C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)[O:7][N:6]=1)[CH2:2][CH2:3][CH3:4]
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]+.
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