Ethyl propiolate → 3-(3-Fluoro-4-nitro-phenyl)-isoxazole-5-carboxylic acid ethyl ester

Participants

Reaction Steps

To a solution of 3-fluoro-4-nitro-benzaldehyde oxime (6 g; 32.6 mmol) in acetonitrile (120 mL) was added hydroxy tosyloxy iodobenzene (16.58 g; 42.3 mmol) and ethyl propiolate (6.38 g; 65.2 mmol) under stirring. The resulting reaction mixture was stirred at 80° C. for 2-3 h. After the completion of the reaction, it was evaporated to dryness. The solid thus obtained was dissolved in ethyl acetate and washed with brine and dried over anhydrous Na2SO4. The solvent was removed and the residue was purified by flash chromatography over silica gel with 20% ethyl acetate in light petroleum to give 6.4 g (74%) of the title compound. IR (KBr): 3134, 3060, 2975, 1717, 1610, 1593, 1522, 1458, 1446 cm−1; MS (m/z): 279 (M−−1); 1H NMR (DMSO-d6) δ: 1.31-136 (t, 3H, CH2CH3), 4.36-4.43 (q, 2H, CH2CH3), 8.04 (d, 1H, J=9.0, 6′-H), 8.09 (s, 1H, 4-H), 8.16 (d, 1H), 8.30 (t, 1H).

Provenance & Evidence