C(O[N:5]=[C:6]([C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=1[OH:15])[CH2:7][CH3:8])(=O)C.Cl>N1C=CC=CC=1>[CH2:7]([C:6]1[C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[O:15][N:5]=1)[CH3:8]A mixture of 12.2 g of 1-(2-hydroxyphenyl)-1-propanone-O-acetyloxime and 120 ml of pyridine is refluxed for 3 h. After cooling, the reaction mixture is poured on to a mixture of ice/water and acidified with c. 130 ml of concentrated hydrochloric acid. After extraction with ethyl acetate, the organic phase is washed three times with water and once with a saturated solution of sodium chloride, dried over sodium sulfate and concentrated under vacuum. The crude product is purified by chromatography over silica gel with ethyl acetate/hexane (1:3) to give 3-ethyl-1,2-benzisoxazole having a refractive index nD20 of 1.5403.
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