1: isopropyl-triphenyl-phosphonium iodide With n-butyllithium in tetrahydrofuran; hexane T=0 - 23°C; 2: 2-bromocyclohex-1-ene-1-carboxaldehyde in tetrahydrofuran; hexane T=0 - 23°C;

1.1: PBr3 / CHCl3 / 1 h / 0 °C 1.2: 81 percent / CHCl3 / 8 h / 20 °C 2.1: n-BuLi / tetrahydrofuran; hexane / 0.5 h / 0 °C 2.2: 80 percent / tetrahydrofuran; hexane / 2 h / 0 °C View Scheme

n-butyllithium in diethyl ether 1.) 0 deg C 2.) R.T., 1 h 3.) 0 deg C, 1 h 4.) R.T., 2 h 5.) reflux, 1 h;