[CH3:1][C:2]1[CH:3]=[C:4]([C:11]2[CH:15]=[C:14]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[O:13][N:12]=2)[CH:5]=[CH:6][C:7]=1[N+:8]([O-])=O.[Cl-].[NH4+].O1CCCC1.O>C(O)C.[Fe]>[NH2:8][C:7]1[CH:6]=[CH:5][C:4]([C:11]2[CH:15]=[C:14]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[O:13][N:12]=2)=[CH:3][C:2]=1[CH3:1]
Ethyl 3-(3-methyl-4-nitrophenyl)isoxazole-5-carboxylate (1.0 equiv.), iron powder (2.0 equiv.), and ammonium chloride (3.0 equiv.) in a mixture of ethanol, tetrahydrofuran and water (4:2:1) were heated to 80° C. for 9 hours. Reaction mixture was cooled and filtered through celite. The filtrate was evaporated to dryness under vacuum and the residue was diluted with EtOAc. The organic layer was washed with water, brine, dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by flash chromatography on silica gel, eluting with 0-2% acetone in chloroform, to provide the title compound as a pale green solid (81%); 1H NMR (300 MHz, DMSO-d6) δ: 1.28-1.33 (t, J=7.2 Hz, 3H), 2.07 (s, 3H), 4.31-4.38 (q, 2H), 5.38 (s, 2H), 6.62-6.65 (d, J=8.4 Hz, 1H), 7.45-7.48 (dd, J=8.1 Hz, 1.8 Hz, 1H), 7.52 (s, 1H), 7.63 (s, 1H); IR (KBr) 3490, 3381, 3135, 2975, 2905, 1725, 1628, 1606, 1471, 1417, 1381, 1279, 1134, 1027, 924, 828, 769 cm−1.
Wird geladen…
