in diethyl ether (N2) or (Ar); addn. of Mg(C4H6)*2THF in portions to soln. of (iPr)2NBCl2 at -80°C within 1 h under stirring; stirring at -80°C for 2 h; slowly warming to 20°C; stirring overnight; filtration; washing with Et2O; evapn. of Et2O-soln. and then distn. in vac.; condensation; elem. anal.;

Na#K in hexane byproducts: NaCl, KCl; (under N2) to stirred Cl2BN(i-Pr)2 in hexane 1,3-butadiene is added (-40°C), after stirring for 3 h the cool mixt. is added at 20°C to Na/K-alloy in hexane (10 min, low temp.-condenser) on applying warm air the mixt. starts to reflux (3 h); filtn. under pressure, hexane is distd. off, distn., elem. anal.;

in neat (no solvent) N2 atmosphere; molar ratio borolene : Rh-complex = 1000:1, stirring (overnight); distn. (vac.); elem. anal.;