3-Bromo-o-xylene → 3-Bromo-4,5-dimethylphenol

Participants

Reaction Steps

The general process was applied to a solution of 3-bromo-o-xylene (185 mg, 1.0 mmol) in 1.0 mL cyclohexane. The borylation step was carried out with HBPin (320 mg, 2.5 mmol) and dppe (8.0 mg, 0.02 mmol, 2 mol %) at 100° C. for 50 hours. After removal of the cyclohexane, the oxidation step was then performed as described above, after which the crude material was dissolved in CH2Cl2 and passed through a plug of silica gel. Evaporation of solvent gave 148 mg pure 10 (74%) as a white wax solid; mp 98-99° C. (lit. 101-102). 1H NMR (300 MHz, CDCl3): δ 6.91 (d, J=2.5 Hz, 1 H), 6.59 (d, J=2.7 Hz, 1 H), 2.25 (s, 6 H); 13C NMR (75 MHz, CDCl3): δ 153.2, 139.3, 128.3, 125.2, 116.9, 116.2, 21.4, 18.3; IR (neat): 3252, 2919, 1606, 1576, 1477, 1451, 1279, 1119, 839 cm−1; LRMS: m/e 200 (M+), 185, 121, 91; HRMS (EI): m/z 199.9839 [(M+); calcd for C8H9BrO: 199.9837]. For a previous preparation see Jacquesy et al., Chem. Soc., Chem. Commun. 110-111 (1980) (bromination of 3,4-dimethylphenol in superacid SbF5-HF, 83% yield) or Fischer and Henderson, Can. J. Chem. 61: 1045-1052 (1983).

Provenance & Evidence