[C:1](O)(=[O:3])[CH3:2].P(=O)(O)(O)O.FC(F)(F)C(OC(=O)C(F)(F)F)=O.[CH2:23]([C:25]1[C:29]([C:30]2[NH:31][C:32]3[C:37]([CH:38]=2)=[CH:36][CH:35]=[CH:34][CH:33]=3)=[C:28]([CH3:39])[O:27][N:26]=1)[CH3:24]>C(#N)C.CCOCC>[C:1]([C:38]1[C:37]2[C:32](=[CH:33][CH:34]=[CH:35][CH:36]=2)[NH:31][C:30]=1[C:29]1[C:25]([CH2:23][CH3:24])=[N:26][O:27][C:28]=1[CH3:39])(=[O:3])[CH3:2]To a mixture of 0.77 milliliters (13.45 m mole) of acetic acid and 0.17 grams (1.47 m mole) of 85% phosphoric acid in 10 milliliters of acetonitrile is added, at room temperature, 1.9 milliliters (13.45 m mole) of trifluoroacetic acid anhydride. The mixture is stirred for 15 minutes and then treated by dropwise addition with 1.0 grams (4.42 m mole) of 2-(3-ethyl-5-methyl-4-isoxazolyl)-indole in 10 milliliters acetonitrile. The mixture is stirred for 31/2 hours at room temperature and then poured onto water and extracted with ether. The ether extracts are dried over magnesium sulfate, filtered and evaporated in vacuo. The resulting oil is filtered through silica gel using 10% methanol/methylene chloride. The solvent is evaporated, and the oil obtained is dissolved in ether. The solution is washed with 10% sodium bicarbonate solution, decolorized with charcoal, dried over magnesium sulfate and evaporated in vacuo. The resulting oil crystallizes upon treatment with ether to give 3-acetyl-2-(3-ethyl-5-methyl-4-isoxazolyl)-indole, m.p. 170°-171°.
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