n-butyllithium in diethyl ether; hexane byproducts: LiCl; under N2; BuLi in hexane is added dropwise to a soln. of Me2S(O)NH in ether, then a soln. of the borolidine in ether is added dropwise, refluxed for 1 h; LiCl is sepd., the solvent is evapd., the oily residue is distd., elem.anal.;

n-butyllithium in diethyl ether; hexane byproducts: LiCl; under N2; BuLi in hexane is added dropwise to a soln. of Me2S(O)NSiMe3 in ether, then a soln. of the borolidine in ether is added dropwise, refluxed; LiCl is sepd., the solvent is evapd., the oily residue is distd.;