The Parent Borylene: Betwixt and Between

Still elusive: The reduction of dimethylimidazol-2-ylidene dichloroborane by sodium naphthalenide has been suggested to provide a borylene that cycloadds to naphthalene to make a borirane. Evidence has been provided that this borirane instead arises from coupling of a boryl radical and sodium naphthalenide. In contrast, reduction of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene dichloroborane and the related dimesityl derivative provide novel CH insertion products that may have arisen from a borylene.