n-BuLi in dichloromethane (N2); CH2Cl2 was added to B compd. at -78°C; soln. of n-BuLi in hexane was added; mixt. was stirred at -78°C for 4 h and at 25°C for 2 h; solvent removed; chromd. (silica gel, pentane); elem. anal.;