Boron tribromide → 4-(2,6-Dibromo-4-nitrophenoxy)-2-isopropylphenol

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Reaction Steps

To a stirred solution of 3,5-dibromo-4-(3′-isopropyl-4′-methoxyphenoxy)-nitrobenzene (1.37 g, 2.98 mmol) in CH2Cl2 (30.0 mL) at −78° C. was added BBr3 (8.93 mL, 8.93 mmol, 1 M solution in CH2Cl2). The reaction mixture was stirred at room temperature for 2.5 h, quenched with ice/water, and stirred cold for several minutes. The reaction mixture was diluted with CH2Cl2 and H2O, partitioned, and the aqueous solution was extracted with CH2Cl2. The combined organic layers were concentrated under reduced pressure and the residue was purified by column chromatography on silica gel, eluting with ethyl acetate-hexanes (1:10) to afford 3,5-dibromo-4-(4′-hydroxy-3′-isopropylphenoxy)nitrobenzene as a solid (1.20 g, 90%): 1H NMR (300 MHz, DMSO-d6): δ 9.19 (s, 1H), 8.64 (s, 2H), 6.73 (m, 2H), 6.37 (m, 1H), 3.12 (m, 1H), 1.16 (d, J=6.0 Hz, 6H); TLC conditions: Uniplate silica gel, 250 microns; Mobile phase=ethyl acetate-hexanes (1:5); Rf=0.46.

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