1: With 2,2,6,6-tetramethyl-piperidine; n-butyllithium; N,N,N',N'',N''-pentamethyldiethylenetriamine in tetrahydrofuran; hexane T=-75°C; 6 h; 2: With tetrabutyl ammonium fluoride T=25°C;

1.1: sec-butyllithium; N,N,N',N'-pentamethyldiethylenetriamine / pentane; tetrahydrofuran / -75 °C 1.2: 75 percent / I2 / pentane; tetrahydrofuran 2.1: 2,2,6,6-tetramethylpiperidine; N,N,N',N'-pentamethyldiethylenetriamine; BuLi / tetrahydrofuran; hexane / 6 h / -75 °C 2.2: 88 percent / tetrabutylammonium fluoride hydrate / 25 °C View Scheme

1.1: 73 percent / BuLi / hexane; tetrahydrofuran / 25 °C 2.1: sec-butyllithium; N,N,N',N'-pentamethyldiethylenetriamine / pentane; tetrahydrofuran / -75 °C 2.2: 75 percent / I2 / pentane; tetrahydrofuran 3.1: 2,2,6,6-tetramethylpiperidine; N,N,N',N'-pentamethyldiethylenetriamine; BuLi / tetrahydrofuran; hexane / 6 h / -75 °C 3.2: 88 percent / tetrabutylammonium fluoride hydrate / 25 °C View Scheme

1.1: pyrrolidine / dimethylformamide / 6 h / Heating 1.2: 33 percent / Zn / acetic acid; H2O / 5 h / 100 °C 2.1: 73 percent / BuLi / hexane; tetrahydrofuran / 25 °C 3.1: sec-butyllithium; N,N,N',N'-pentamethyldiethylenetriamine / pentane; tetrahydrofuran / -75 °C 3.2: 75 percent / I2 / pentane; tetrahydrofuran 4.1: 2,2,6,6-tetramethylpiperidine; N,N,N',N'-pentamethyldiethylenetriamine; BuLi / tetrahydrofuran; hexane / 6 h / -75 °C 4.2: 88 percent / tetrabutylammonium fluoride hydrate / 25 °C View Scheme