Lewis Acid Chelation of [NR]2- by 2,2‘-Diborabiphenyl:  9,11-Diboratacarbazole Heterocycles

A new heterocyclic framework, the dianionic 9,11-diboratacarbazole, has been prepared from a bis(trimethylphosphine)-stabilized 2,2‘-diborabiphenyl derivative, 1, and H2NR (R = Ph, CH2C6H4-p-OMe). The heterocyclic framework is formally assembled via Lewis acid chelation of the [NR]2- dianion by 2,2‘-diborabiphenyl. These dianions are isoelectronic with the well-studied fluorenyl monoanion.