Single and double activation of acetone by isolobal B[triple bond, length as m-dash]N and B[triple bond, length as m-dash]B triple bonds

B[triple bond, length as m-dash]N and B[triple bond, length as m-dash]B triple bonds induce C–H activation of acetone to yield a (2-propenyloxy)aminoborane and an unsymmetrical 1-(2-propenyloxy)-2-hydrodiborene, respectively. DFT calculations showed that, despite their stark electronic differences, both the B[triple bond, length as m-dash]N and B[triple bond, length as m-dash]B triple bonds activate acetone via a similar coordination-deprotonation mechanism. In contrast, the reaction of acetone with a cAAC-supported diboracumulene yielded a unique 1,2,3-oxadiborole, which according to DFT calculations also proceeds via an unsymmetrical diborene, followed by intramolecular hydride migration and a second C–H activation of the enolate ligand.