1.1: N,N,N',N'',N''-pentamethyldiethylenetriamine; tert-butyllithium / tetrahydrofuran / 1 h / -25 °C 1.2: 60 percent / tetrahydrofuran / -25 - 20 °C 2.1: 76 percent / aq. HCl / ethyl acetate / 1 h / 20 °C View Scheme