1: 85 percent / 1.) hexamethylphosphoric triamide, BuLi / tetrahydrofuran; hexane / 2 h / -70 - 0 °C 2: Li in EtNH2 / tetrahydrofuran / 0.5 h / -70 °C / further reagents at other conditions; further coupled p-tosyl sulfones; isomerization of olefinic bond View Scheme

1: 85.3 percent / t-BuOK / tetrahydrofuran; dimethylformamide / 2.5 h / -40 - 20 °C 2: 77 percent / naphthalenyllithium / tetrahydrofuran / 2 h / -78 °C View Scheme