1: With magnesium in tetrahydrofuran T=20°C; 2 h; 2: With boric acid trimethyl ester in tetrahydrofuran T=20°C; 5 h; Further stages.;

magnesium in tetrahydrofuran (Ar); dissolving Mg and aryl bromide in dry THF, stirring for 2 h at room temp., addn. of borate deriv. at -78°C, stirring for 5 h at room temp.; washing with HCl, water and chloroform, recrystn. (hexane);