1: dimethyl zinc With titanium tetrachloride in dichloromethane; toluene T=-30°C; 0.5 h; 2: 1-(3,5-dimethoxyphenyl)-7-phenoxyheptan-1-one in dichloromethane; toluene T=20°C; 6 h; Further stages.;

1.1: magnesium turnings / tetrahydrofuran / 1.5 h / 20 °C 1.2: 75 percent / tetrahydrofuran / 6 h / 20 °C 2.1: TiCl4 / CH2Cl2; toluene / 0.5 h / -30 °C 2.2: 84 percent / CH2Cl2; toluene / 6 h / 20 °C View Scheme

boron tribromide in dichloromethane T=-78 - 20°C; Yield given;