n-butyllithium; potassium hydride in tetrahydrofuran; pentane T=-78 - 20°C; 3.5 h; Inert atmosphereDarkness;

1: With potassium hydride in tetrahydrofuran T=0°C; 0.25 h; 2: With tert.-butyl lithium in tetrahydrofuran; pentane 0.183333 h; 3: With boric acid trimethyl ester in tetrahydrofuran; pentane T=-78 - 20°C;