Step 3: Preparation of tert-butyl [1-(4-bromophenyl)-1-methylethyl]carbamate
To a suspension of 2-(4-bromophenyl)-2-methylpropanamide (3 g) in tert-butanol (31 mL), [bis(trifluoroacetoxy)iodo]benzene (8 g) was added in batches at room temperature. The reaction mixture was stirred under reflux conditions for 30 minutes. Subsequently, pyridine (3 mL) was added to the mixture. After continuing to stir under reflux conditions for 1 hour, the reaction mixture was concentrated to dryness. The residue was dissolved in benzene and washed sequentially with 1 M aqueous citric acid (2 times), aqueous sodium bicarbonate (5 times) and brine. The organic phase was dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure. Purification by column chromatography (eluent: 0-20% hexane solution of ethyl acetate) gave the target product (3.29 g, 84% yield).
1H NMR (CDCl3, 400MHz) δ: 7.43 (d, J = 8.6Hz, 2H), 7.27 (d, J = 8.6Hz, 2H), 1.59 (br s, 6H), 1.48-1.05 (m, 9H).
![[1-(4-Bromo-phenyl)-1-methyl-ethyl]-carbamic acid tert-butyl ester](/CAS/20200401/GIF/214973-83-8.gif)