[N:1]([C:4](=[CH:9][C:10]1[CH:15]=[CH:14][C:13]([Cl:16])=[C:12]([F:17])[CH:11]=1)[C:5]([O:7][CH3:8])=[O:6])=[N+]=[N-]>C1(C)C(C)=CC=CC=1>[Cl:16][C:13]1[C:12]([F:17])=[C:11]2[C:10]([CH:9]=[C:4]([C:5]([O:7][CH3:8])=[O:6])[NH:1]2)=[CH:15][CH:14]=1A solution of methyl 2-azido-3-(4-chloro-3-fluorophenyl)propenoate (15.08 g, 59 mmol) in xylene (200 mL) was added dropwise to stirred xylene (1 L) under reflux. The mixture was stirred for 3 h, cooled to room temperature, concentrated in vacuo and purified by column chromatography [SiO2; isopropyl ether-hexane (5:2)] to give the product (2.3 g, 17% yield) as a colourless solid: IR νmax (Nujol)/cm−1 3298, 1709, 1460, 1377, 1204 and 737; NMR δH (400 MHz, CDCl3) 3.85 (3H, s) 7.09-7.15 (1H, m) 7.21 (1H, m) 7.38 (1H, m) and 9.05 (1H, brs).
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