in tetrahydrofuran; diethyl ether; hexane byproducts: LiCl; to a soln. of LiCHCl2 (THF, hexane) boronic ester in diethyl ether was added at -100°C in one portion, the soln. was allowed to warm slowly to 20-25°C and kept overnight, Ar atm.; CH2Cl2 was added to precipitate LiCl, filtration, evapn. in vac., distn.; elem. anal.;