magnesium in tetrahydrofuran 1 h; Heating;

in tetrahydrofuran; 1,4-dioxane under Ar ZnCl2(thf)2/THF stirred at room temp. for 2 h, at 50°C for 1 h, MgMes2/dioxane/THF added, stirred; solvent removed, Et2O added, filtered, residue washed (heated ether), elem. anal.;