Carbamic acid, (4-bromo-2-methoxyphenyl)-, 1,1-dimethylethyl ester (9CI)

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To 2.4 g (20.6 mmol, 1.2 eq) of 35% potassium hydride suspended in 70 ml of anhydrous THF under an argon atmosphere, at room temperature 5.2 g (17.2 mmol) of tert-butyl-N-(4-bromo-2-methoxyphenyl)carbamate 4 diluted in 60 ml of anhydrous THF is added dropwise. This mixture is shaken for 10 min before cooling to −78° C. When this temperature is reached, 23.5 ml (35.3 mmol, 2.05 eq) of 1.5 M tert-butyllithium is added through a cannula in hexane diluted in 50 ml of anhydrous THF and previously cooled to −78° C. The reaction is allowed to progress for 20 min at −78° C. before adding 6.2 ml (41.3 mmol, 2.4 eq) of allyl(chloro)dimethylsilane all at once. The temperature is allowed to rise to −10° C. then the medium is hydrolyzed with a small amount of water. Next, 90 ml of AcOEt is added and the organic phase is washed with H2O (3×90 ml), 1 M NaHSO4 (2×90 ml), then a saturated aqueous solution of NaCl (1×90 ml), and lastly, dried on MgSO4. Concentration under vacuum gives an orange oil which is purified by column chromatography (eluent petroleum ether/AcOEt 9:1), producing 4.28 g of a colorless oil (yield: 77%). is added dropwise previously cooled to −78° C to progress for 20 min at −78° C. to rise to −10° C. the organic phase is washed with H2O (3×90 ml), 1 M NaHSO4 (2×90 ml) a saturated aqueous solution of NaCl (1×90 ml), and lastly, dried on MgSO4 Concentration under vacuum gives an orange oil which is purified by column chromatography (eluent petroleum ether/AcOEt 9:1)