in toluene T=100°C; 48 h; Schlenk technique;

in toluene 2 equiv. (C5Me5)2MgCl*THF, refluxed (24 h);

in toluene at 95-100°C, excess of THF-adduct, stirring under Ar for 2 d; filtering, washing with hot toluene, slurriing in ether, filtering, washing with diethyl ether, drying in vac., recrystn. from hot toluene;