1: With n-butyllithium in diethyl ether; hexane T=-78 - 0°C; 2: in diethyl ether; hexane; N,N-dimethyl-formamide T=50°C; Peterson elimination; 2 h; Further stages.;

1: 1-bromo-1-trimethylsilylethene With tert.-butyl lithium in diethyl ether; pentane T=-78°C; 2: 1,5-Diphenylpentan-3-one in diethyl ether; pentane T=0°C; 3: in diethyl ether; N,N-dimethyl-formamide; pentane T=80°C; Peterson allenation; Further stages.;