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0 °C

2-Bromo-4-tert-butylphenyl methyl carbonate (5.0 g, 17.4 mmol) was added portion-wise to H2SO4 (9.3 mL, 174.1 mmol) to generate a colorless homogeneous solution. This solution was then cooled to 0° C. and treated with KNO3 (2.1 g, 20.9 mmol) portion-wise maintaining the internal temperature below 5° C. The reaction was stirred for 2 h and then poured on ice water. The aqueous layer was extracted with dichloromethane (3×10 mL). The combined organic extracts was dried over Na2SO4, filtered and concentrated. Purification by silica gel chromatography (10% ethyl acetate/hexane) provided 2-bromo-4-tert-butyl-5-nitrophenyl methyl carbonate (4.4 g, 76% yield). 1H NMR (400.0 MHz, DMSO-d6) δ 7.97 (s, 1H), 7.92 (s, 1H), 3.90 (s, 3H), 1.34 (d, J=5.4 Hz, 9H).

1. temperaturemaintaining the internal temperature below 5° C
2. additionpoured on ice water
3. extractionThe aqueous layer was extracted with dichloromethane (3×10 mL)
4. dry with materialThe combined organic extracts was dried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated
7. customPurification by silica gel chromatography (10% ethyl acetate/hexane)