in dichloromethane under N2; soln. of C6F5Cu in CH2Cl2 added dropwise over 20 min to soln. of BCl3 (3 equiv) in CH2Cl2 at -78 °C; mixt. stirred at -78 °C for 1 h and then allowed to slowly warm to room temp. and stirred for 3 h; after filtration all volatiles slowly removed under high vac. first at -25 °C and subsequently over 3 h at 0 °C; crude product distd. under dynamic vac. at ca. 40 °C into cold trap (liq. N2); vac. transfer into storage flask;