1: methyl propargyl bromide With aluminium; PbCl2 in tetrahydrofuran T=0°C; 1 h; Inert atmosphere; 2: cyclohexanone in tetrahydrofuran T=0°C; Inert atmosphere;

titanium tetrachloride in dichloromethane T=-78°C; Yield given;

1: 60 percent / toluene 2: 86 percent / LDA / tetrahydrofuran / 0 °C View Scheme