Unexpected rearrangements in the synthesis of an unsymmetrical tridentate dianionic N-heterocyclic carbene

Abstract
Starting from the same ethylenediamine species, three valuable carbene precursors were synthesized under differing conditions: a tridentate dianionic N-heterocyclic carbene bearing an aniline, a phenol and a central dihydroimidazolium salt, its benzimidazolium isomer by intramolecular rearrangement and a dicationic benzimidazolium-benzoxazolium salt by changing the Brønsted acid from HCl to HBF4. A DFT study was performed to understand the rearrangement pathway. The structure of a bis[(NCO)carbene] zirconium complex was determined. © 2013 The Royal Society of Chemistry.

Citation
Despagnet-Ayoub E, Miqueu K, Sotiropoulos J-M, Henling LM, Day MW, et al. (2013) Unexpected rearrangements in the synthesis of an unsymmetrical tridentate dianionic N-heterocyclic carbene. Chem Sci 4: 2117. Available: http://dx.doi.org/10.1039/c3sc22171g.

Acknowledgements
This work was supported by a KAUST Center-In-Development Grant to King Fahd University of Petroleum and Minerals (Dhahran, Saudi Arabia) and the USDOE Office of Basic Energy Sciences (Grant no. DE-FG03-85ER13431). The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology, CHE-0639094.

Publisher
Royal Society of Chemistry (RSC)

Journal
Chemical Science

DOI
10.1039/c3sc22171g

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