129316-09-2

1,3-dibromo-5-tert-butylbenzene is a versatile building block that can be used to create a range of compounds.

To a stirring solution of 1,3-dibromo-5-tert-butylbenzene (5.0 g, 17.0 mmol) in dry ether at ?78°C, n-Butyllithium (1.1 equiv.) was added dropwise. After stirring for 30 min under the N2 atmosphere, N-methoxy-N-methylacetamide (2.4 ml, 22.1 mmol) was added dropwise. The reaction mixture was allowed to warm to room temperature and stirred for 12 h. After quenching with a saturated solution of ammonium chloride, water was added, and the mixture was extracted with ether (2 × 150 ml). The combined organic extracts were washed with water (2 × 200 ml), dried with MgSO4 and evaporated to give a crude product. Purification was done by silica gel flash column chromatography using ethyl acetate: n-hexane mixture (v:v = 1:28) as eluent to give 1-(3-bromo-5-(tert-butyl)phenyl)ethanone as pale yellow oil.

The general procedure for the synthesis of 1,3-dibromo-5-(tert-butyl)benzene from 2,6-dibromo-4-tert-butylaniline was as follows: 2,6-dibromo-4-tert-butylaniline (5 g, 16.3 mmol) was dissolved in 200 mL of ethanol at 50 °C. Concentrated sulfuric acid (25 mL) was slowly added to this solution and the mixture was subsequently heated to 70°C. Sodium nitrite (NaNO2, 3.1 g, 44.6 mmol) was added in batches over a period of 45 min, taking care to control the reaction temperature in order to avoid intense exotherm and rapid release of nitrogen (N2). After the release of nitrogen was significantly reduced, the reaction mixture was continued to be heated at 80°C for 13 hours. Upon completion of the reaction, the mixture was cooled to room temperature and poured into ice water. The reaction mixture was extracted with ethyl acetate (3 x 100 mL) and the combined organic phases were dried over anhydrous sodium sulfate (Na2SO4). After filtration, the solvent was evaporated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (using petroleum ether as eluent) to finally obtain pure 1,3-dibromo-5-tert-butylbenzene (3.790 g, 79.6% yield). The structure of the product was confirmed by 1H NMR, 13C NMR and high-resolution mass spectrometry (HRMS).1H NMR (CDCl3, 500 MHz, ppm): δ 7.49 (s, 1H, Ar-H), 7.44 (dd, J1 = 0.80 Hz, J2 = 0.70 Hz, 2H, Ar-H), 1.30 (s, 9H, C(CH3)3- H); 13C NMR (CDCl3, 125 MHz, ppm): δ 155.29, 131.11, 127.57, 122.72, 35.08, 31.01. HRMS (ESI): m/z calculated value [M + COOH - H] C11H12O2Br2: 335.9179; measured value: 335.9061.

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