Ethanol → ethyl 6-[(hydroxyimino)methyl]-2-(trifluoromethyl)-2H-1-benzopyran-3-carboxylate

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Reaction Steps

A 50 mL round bottom flask was charged with hydroxylamine HCl (0.255 g, 3.67 mmol), ethyl 6-formyl-2-(trifluoromethyl)-2H-1-benzopyran-3-carboxylate (Example 75, Step 1) (1.00 g, 3.34 mmol), sodium acetate (0.301 g, 3.67 mmol), ethanol (10 mL), and H2O (2 mL). The reaction was stirred at room temperature for 18 hours, then diluted with H2O and diethyl ether. The layers were separated and the organic phase washed with H2O, brine, dried over MgSO4, filtered, and concentrated in vacuo yielding an orange semi-crystalline mass. Recrystallization of this solid from hot ethyl acetate and isooctane yielded the oxime (0.578 g, 55%): mp 113.0–116.2° C. 1H NMR (acetone-d6/300 MHz) 10.46 (s, ca.1 exch.), 8.11 (s, 2H), 7.92 (s, 1H), 7.72 (d, 1H, J=2 Hz)), 7.68 (dd, 1H, J=8.5, 2.0 Hz), 7.07 (d, 1H, J=8.5 Hz), 5.89 (q, 1H, J=7.1 Hz), 4.43−4.22 (m, 2H), 1.34 9t, 3H, J=7.3 Hz). FABLRMS m/z 316 (M+H). EIHRMS m/z 315.0719 (M+, Calc'd 315.0733). Anal. Calc'd for C14H12F3N1O4: C, 53.34; H, 3.84; N 4.44. Found: C, 53.85; H, 3.90; N, 4.19.

Provenance & Evidence