Br[CH2:2][C:3]1[CH:8]=[CH:7][C:6]([Cl:9])=[C:5]([Cl:10])[CH:4]=1.[N-:11]=[N+:12]=[N-:13].[Na+].[C:15]([O:19][CH2:20][CH3:21])(=[O:18])[C:16]#[CH:17]>CN(C=O)C>[Cl:10][C:5]1[CH:4]=[C:3]([CH2:2][N:11]2[CH:17]=[C:16]([C:15]([O:19][CH2:20][CH3:21])=[O:18])[N:13]=[N:12]2)[CH:8]=[CH:7][C:6]=1[Cl:9]To a solution of 4-(bromomethyl)-1,2-dichlorobenzene (2 g, 8.3 mmol), in DMF (30 mL) was added sodium azide (0.65 g, 1.2 eq). The reaction was stirred at 80° C. for 3 hours. The solvent was then evaporated and the residue was dissolved in DCM and washed with water. The organic phase was dried over sodium sulphate and the solvent was evaporated. The crude azido compound was dissolved in ethanol (100 mL) and ethyl 2-propynoate (1 mL, 1.2 eq) was added. The reaction was stirred to reflux for 24 hours. The reaction was not completed and 0.3 mL of ethyl 2-propynoate was added and the reaction was stirred to refleux for more 24 hours. Ethanol was evaporated and the reaction was dissolved in DCM and washed with water, dried over sodium sulphate and concentrated in vacuo. Purification by flash chromatography eluting with DCM and DCM/MeOH 99/1 gave the title compound as a white solid (1.5 g, 60%). LC/MS: m/z 300 (M+H)+. Rt: 3.12 min.
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