in tetrahydrofuran 4 h; Ambient temperature;

1: 1.) BuLi / 1.) ether, hexane, RT, 2 h, 2.) pentane, RT, 1 h 2: hexamethyl phosphoric acid triamide / diethyl ether / 4 h View Scheme

N,N,N',N',N'',N''-hexamethylphosphoric triamide in diethyl ether 4 h; Title compound not separated from byproducts;

1: 77.3 percent / hexane / 2 h / Ambient temperature 2: 70.7 percent / tetrahydrofuran / 4 h / Ambient temperature View Scheme

n-butyllithium in diethyl ether byproducts: LiCl; Ar-atmosphere; treatment of ligand with BuLi, ZrCl4 addn., stirring for 1 h; evapn., washing (pentane), extn. into CH2Cl2, filtration (Na2SO4), vol. reduction, recrystn. (layering CH2Cl2 soln. with hexane, -30°C);