[CH2:1]([C:4]1[C:9]([Cl:10])=[C:8]([Cl:11])[CH:7]=[CH:6][C:5]=1[OH:12])[CH2:2][CH3:3].[H-].[Na+].[Br:15][CH2:16][CH2:17][CH2:18][CH2:19][CH2:20]Br.[I-].[K+]>O.C(OCC)(=O)C.CN(C)P(N(C)C)(N(C)C)=O.O1CCCC1>[CH2:1]([C:4]1[C:9]([Cl:10])=[C:8]([Cl:11])[CH:7]=[CH:6][C:5]=1[O:12][CH2:20][CH2:19][CH2:18][CH2:17][CH2:16][Br:15])[CH2:2][CH3:3]To a solution of 3.12 g. of 2-propyl-3,4dichlorophenol in 30 ml. of dry tetrahydrofuran and 30 ml. of dry hexamethylphosphoramide were added 0.72 g. of a 50% sodium hydride dispersion in oil. Two milliliters of 1,5-dibromopentane were then added followed by a catalytic amount of potassium iodide. The reaction was stirred overnight under a nitrogen atmosphere at 60°-70° C. The reaction was then cooled to room temperature, ethyl acetate and water were added, and the solution was evaporated to dryness. Ethyl acetate and water were added to the residue and the layers were separated. The ethyl acetate layer was washed with dilute acid to remove residual hexamethylphosphoramide. The ethyl acetate was then washed with a saturated sodium chloride solution, filtered through sodium sulfate, and evaporated to dryness. The residue was purified by high pressure liquid chromatography to provide 1.6 g. of the desired bromo intermediate. NMR.
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