in diethyl ether to suspn. of PhBCl2 in Et2O slowly added MgC4H6*2THF at -80 °C with stirring under N2, stirred for 2 h at -80 °C and for 1 h at 20°C; filtered, evapd. in vac., distd. bei 40-60 °C at 1E-6 bar; elem.anal.;