in pentane inert atmosphere, addn. of soln. of tin compound to soln. of Et2BBr at -30°C, stirring (25°C, 1 h); pptn. of (CH3)3SnBr at -78°C, filtration (-78°C), reductn.of volume (reduced presssure), warming to room temp., addn. (pentane), cooling (-78°C), filtration, reductn. of volume (vacuum), distill ation (vacuum, low temperature);

in pentane byproducts: LiBr; inert atmosphere, addn. of soln. of excess Et2BBr to suspension of lithium compound below -40°C with stirring; filtration from LiBr, removement of solvent (reduced pressure), distillation (40-50°C, 0.3 Torr);

in neat (no solvent) dropwise addn. of 2 equiv. stannane to Et2BCl at -40°C, stirring at -40°C for 60 min; distn. into cold trap (0.001 Torr);

in neat (no solvent) Ar atmosphere, slow heating to 100°C, 120°C, gentle reflux(2 h), cooling to room temp.; removement of volatiles (vacuum), condensation of Et3B;