1: Methyltriphenylphosphonium bromide With n-butyllithium in tetrahydrofuran; hexane T=0 - 23°C; 2: (1S,9R)-6,10,10-trimethylbicyclo[7.2.0]undec-(5E)-en-2-one in tetrahydrofuran; hexane T=23°C; 1 h; Further stages.;