in pentane byproducts: (CH3)3SnCl; condensation of B-compd. into a soln. of (Me3Sn)2O in pentane at -196°C under N2, warming to room temp.; removal of volatile compds., sepn. of volatile compds. into product and solvent fractions at -78°C and -196°C, respectively, further sepn. yields (MeBO)3 and further B-compd. at -40°C, at-25°C oxadiborinane;