1: N'-(2-Bromo-4-methylphenyl)-N,N-dimethylurea With methyllithium in tetrahydrofuran; diethyl ether T=0°C; 2: With tert.-butyl lithium in tetrahydrofuran; diethyl ether; n-heptane T=0°C; 1 h; 3: carbon monoxide in tetrahydrofuran; diethyl ether; n-heptane T=0°C; 0.5 h;