Metal-Mediated Cyclisation of Iminoboranes: Organometallic Chemistry and Functional BN-Isosteres
Final Report Abstract
The majority of the results of this project concern either the expansion of the family of 1,2-azaborinines and the exploration of reactivity of rhodium 1,2-azaborete complexes, about which little was previously known. In both regards, a large body of new compounds and reactions were uncovered, leading to the publication of three original research articles in top journals. The somewhat temperamental synthesis of 1,2-azaborinines from rhodium 1,2-azaborete complexes hampered our efforts to install more exotic, functional units into these heterocyclic species. However, the aforementioned discovery of a new route to 1,2-azaborinines using the more reactive 1-rhoda-3,2-azaborole complexes, which appears to allow reaction with more bulky alkyne components, gives us hope that the construction of a wider range of heterocycles may be possible in future work. These possibilities are currently under investigation in our laboratories. A number of research results remain to be published, including a range of novel reactions of rhodium 1,2-azaborete complexes and 1-rhoda-3,2-azaborole complexes (e.g. with HCl, azides, pyridines, isocyanides and carbodiimides). A particular highlight is the reaction of a 1-rhoda-3,2-azaborole complex with an iminoborane, leading to the first known example of a 1,3-diaza-2,4-diborinine, with a C2B2N2 core and alternating B-N-B-N connectivity. These results require further investigation. Overall, although the azaborinine heterocycles were initially our major focus in this project, the surprisingly reactive rhodium-containing intermediate may turn out to be the true stars of the show: they have already demonstrated a fascinating diversity of reactions, and we have high hopes for their future chemistry.
Publications
- Recent Developments in Azaborinine Chemistry, Eur. J. Inorg. Chem. 2017, 4353–4368
G. Bélanger-Chabot, H. Braunschweig, D. K. Roy
(See online at https://doi.org/10.1002/ejic.201700562) - Cleavage of BN triple bonds by main group reagents, Chem. Commun. 2018, 54, 8210–8213
L. Winner, A. Hermann, G. Bélanger-Chabot, O. F. González-Belman, J. O. C. Jiménez-Halla, H. Kelch, H. Braunschweig
(See online at https://doi.org/10.1039/C8CC02317D) - Diverse Ring-Opening Reactions of Rhodium η4-Azaborete Complexes, Chem. Sci. 2020, 11, 9134–9140
M. Heß, T. E. Stennett, R. Bertermann, M. Schock, M. Schäfer, T. Thiess, H. Braunschweig
(See online at https://doi.org/10.1039/d0sc02283g) - Rhodium-Mediated Stoichiometric Synthesis of Mono-, Bi-, and Bis-1,2-Azaborinines: 1-Rhoda-3,2-azaboroles as Reactive Precursors, Chem. Eur. J.
M. Heß, I. Krummenacher, T. Dellermann, H. Braunschweig
(See online at https://doi.org/10.1002/chem.202100795)
