ClC(OCC)=O.[Br:7][C:8]1[CH:13]=[CH:12][C:11]([C@@H:14]2[CH2:16][C@H:15]2[C:17]([OH:19])=O)=[CH:10][CH:9]=1.CCN(CC)CC.[N-:27]=[N+:28]=[N-:29].[Na+]>CC(C)=O.O>[Br:7][C:8]1[CH:13]=[CH:12][C:11]([C@@H:14]2[CH2:16][C@H:15]2[C:17]([N:27]=[N+:28]=[N-:29])=[O:19])=[CH:10][CH:9]=1
Ethyl chloroformate (1.9 mL) was added to a solution of (trans)-2-(4-bromophenyl)cyclopropanecarboxylic acid (Intermediate C, 4 g, 0.0165 mol) and Et3N (2.51 mL, 0.0199 mol) in acetone (60 mL) at −20° C., stirred at same temperature for 1 h, then a solution of NaN3 (1.3 g, 0.0199 mol) in water (5 mL), was added and stirred for 30 mins at rt. After completion of reaction, checked by TLC, the solvent was evaporated and crude residue was dissolved in ethyl acetate (100 mL), washed with water (40 mL), dried over anhydrous Na2SO4, filtered and evaporated to get (trans)-2-(4-bromophenyl)cyclopropanecarbonyl azide (4 g). The crude residue is carried to next step without further purification.
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