I-isopropyl-2-methyl-I, 3, 2-diazaborolidine (la) can be prepared either by method C, by method A, using the ethylenediamines and H, CB [N (CH,),], to eliminate HN (CH3) z, or by method B, starting with CH3BBr2, NR,, and the corresponding ethylenediamines. The unsaturated 2, 3-dihydro-l HI, 3, tdiazaboroles lt7b are synthesized by catalytic dehydrogenation in either liquid (lb-3b) or gaseous (4b-7b) state. Diazaboroles can act as ...