1: phenyl-carbamic acid tert-butyl ester With tert.-butyl lithium in tetrahydrofuran; pentane T=-70 - -20°C; 2.5 h; 2: (4-oxo-cyclohexyl)-carbamic acid tert-butyl ester With potassium tert-butylate in tetrahydrofuran; pentane T=-70 - 20°C; 3: With hydrogenchloride in tetrahydrofuran; diethyl ether; water; pentane T=0°C; pH=7;

t-BuOK; tert.-butyl lithium 1.) pentane, THF, a) -70 deg, 0.5 h, b) -20 deg, 2.5 h, 2.) THF, a) from -70 deg to RT, 4 h, b) RT, 16 h; Yield given. Multistep reaction;

trifluoroacetic acid in dichloromethane 1 h; Ambient temperature;

1: 1.) NaH / 1.) DMF, 20 deg, 0.5 h, 2.) DMF, 20 deg, 1 h 2: 78 percent / trifluoroacetic acid / CH2Cl2 / 2 h / Ambient temperature View Scheme