tert-Butanol → (2-Bromo-5-methoxy-3-methyl-phenyl)-carbamic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 2-bromo-5-methoxy-3-methyl-benzoic acid ((Example 198: step a) 3.39 g, 13.8 mmol) in dry tert-butanol was treated with DPPA (3.58 mL, 16.6 mmol) dropwise and stirred 5 min. The solution was treated with diisopropylethylamine (2.89 mL, 16.6 mmol) and heated to 80° C. 17.5 h. Tert-butanol was removed in vacuo. The residue was taken up in EtOAc and washed with saturated aqueous NaHCO3 (2×60 mL) and water (1×60 mL). The combined organic layers were dried over MgSO4 and concentrated in vacuo. Silica gel chromatography (10% EtOAc in hexanes) afforded the product (2-bromo-5-methoxy-3-methyl-phenyl)-carbamic acid tert-butyl ester (3.05 g, 70%) as a colorless oil. 1H NMR (CDCl3): δ 7.701 (d, 1H, J=1.6 Hz), 7.146 (s, NH), 6.517 (d, 1H, J=3.2 Hz), 3.797 (s, 3H), 2.360 (s, 3H), 1.534 (s, 9H).

Provenance & Evidence