sodium hydride T=0°C; 5 h;

1: With n-butyllithium in tetrahydrofuran; hexane T=0°C; 2 h; 2: With boric acid trimethyl ester in tetrahydrofuran; hexane T=0 - 20°C; 3: With ammonium chloride in tetrahydrofuran; hexane; water T=20°C; 1 h;