[CH3:1][O:2][C:3](=[O:18])[C:4]1[CH:9]=[CH:8][C:7]([CH2:10]Br)=[CH:6][C:5]=1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1.[N-:19]=[N+:20]=[N-:21].[Na+]>[I-].C([N+](CCCC)(CCCC)CCCC)CCC.CN(C=O)C.O>[CH3:1][O:2][C:3](=[O:18])[C:4]1[CH:9]=[CH:8][C:7]([CH2:10][N:19]=[N+:20]=[N-:21])=[CH:6][C:5]=1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1A mixture of 4-bromomethyl-2-phenylbenzoic acid methyl ester (1.5 g, 4.9 mmol), sodium azide (1.28 g, 19.7 mmol) and tetrabutylammonium iodide (1.3 g, 4.9 mmol) in DMF (16 mL) was heated at 75° C. for 18 hours. The reaction mixture was diluted with water and extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered and concentrated in vacuo. Chromatography on silica gel (15% ethyl acetate-hexanes) to give the desired azide as a colorless oil (1.01 g).
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