S(=O)(=O)(O)O.[Br:6][C:7]1[CH:8]=[C:9](C(O)=O)[C:10]2[O:14][CH2:13][CH2:12][C:11]=2[CH:15]=1.[N-:19]=[N+]=[N-].[Na+]>C(Cl)(Cl)Cl>[NH2:19][C:9]1[C:10]2[O:14][CH2:13][CH2:12][C:11]=2[CH:15]=[C:7]([Br:6])[CH:8]=1Concentrated sulfuric acid (8.8 ml) was added over 5 min to a stirred mixture of 5-bromo-2,3 -dihydrobenzofuran-7-carboxylic acid (0.55 g, 2.3 mmol) in chloroform (27 ml) at 45° C. Sodium azide (0.737 g, 11.3 mmol) was then added portion-wise over 0.5 h and the temperature was maintained for a further 1 h after which time the mixture was poured onto ice (100 g) and extracted with chloroform (2×50 ml). The aqueous phase was basified to pH 12 with 40% sodium hydroxide solution and extracted with chloroform (2×50 ml). The extract was dried (Na2SO4), concentrated, and the residue purified by column chromatography over silica gel eluting with a gradient of acetone/toluene to give the title compound (D14) as a solid (63 mg, 13%), MH+ 214/216.
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