1: tert-butyl N-(4-trifluoromethoxyphenyl)carbamate With tert.-butyl lithium in tetrahydrofuran; pentane T=-50°C; 2 h; 2: N,N-dimethyl-formamide in tetrahydrofuran; pentane T=25°C;

1.1: 99 percent / toluene / 100 °C 2.1: t-BuLi / pentane; tetrahydrofuran / 2 h / -50 °C 2.2: 86 percent / pentane; tetrahydrofuran / 25 °C View Scheme

1.1: 99 percent / toluene / 100 °C 2.1: t-BuLi / pentane; tetrahydrofuran / 2 h / -50 °C 2.2: 86 percent / pentane; tetrahydrofuran / 25 °C View Scheme

1: With hydrogen bromide 0.25 h; Heating; 2: With hydrogen bromide; copper(I) bromide; sodium nitrite 0.75 h; Heating;