boron trichloride in toluene T=-78 - 20°C;

in toluene under Ar; BCl3 added to soln. of N-compd. in toluene at -78°C, mixt. allowed to warm to room temp., stirred for 7 h; 1-(chloro(diisopropylaminoboryl)imidazole filtered off, filtrate evapd. under vac., residue recrystd. from toluene at -18°C;