PhD candidate (M/F) in organic chemistry - 2-Pyridylidene ligands for iron catalysis

This thesis is funded as part of an individual research project (2Pyr4FeCat) led by a young researcher (JCJC) supported by the French national research agency (ANR).
All work will be carried out at the Institute of Chemical Sciences of Rennes (ISCR), located on the Beaulieu campus, within the Organometallics: Materials & Catalysis (OMC) group under the supervision of L. Jarrige (CR CNRS) and G. Alcaraz (DR CNRS).
The doctoral student (M/F) will be attached to the Doctoral School Sciences of Matter, Molecules and Materials (S3M, No. 638) co-accredited by the University of Rennes (UR) (supporting establishment), the University Bretagne Ouest (UBO), the National School of Chemistry of Rennes (ENSCR) and the National Institute of Applied Sciences of Rennes (INSA).

Since their discovery in early 1990's,[1] stable N-Heterocyclic Carbenes (NHCs) were subjected to an impressive development in organometallic catalysis, leading to a wide and successful use as ligands in many metal-catalysed transformations.[2] The design of complementary architectures, displaying various steric and electronic properties, easy to access, and able to induce new types of reactivity, remains a current issue. In this context, the proposed research project focuses on an emerging class of NHC ligands named 2-pyridylidenes with exceptional electronic properties, with both strong electron-donation as well as ligand binding energies.[3] Their synthesis is easy with short routes, directly involving the pyridine core as well as robust, reproducible and scalable transformations, thus offering a wide choice of structural modulations.

This project aims to study the 2-pyridylidene scaffold as ligand in transition-metal complexes and enlarge the current very limited library of catalytically active metal complexes.[4] A particular emphasis will be placed on earth-abundant metals, and especially iron. To achieve these objectives, the proposed research project is divided into two distinct parts. The first one consists in the extension of the structural diversity of this class of ligands through an important synthetic work in order to acquire a wide library of (a)chiral diversely substituted pyridiniums salts as 2-pyridylidene precursors. Once these species in hands, they will be subjected to the coordination with the metal center in order to obtain the corresponding (a)chiral transition metal-complexes (Part 2). The catalytic activity as well as the induced selectivity will be evaluated for all the newly prepared organometallic species in various transformations of high interest for both academic and industrial settings.[5]

References:
[1] Arduengo, A. J.; Harlow, R. L.; Kline, M. J. Am. Chem. Soc. 1991, 113, 361.
[2] Pour d'excellents livres traitant des NHCs, voir : a) N-Heterocyclic Carbenes in Synthesis (Ed.: S. P. Nolan), Wiley-VCH, Weinheim, 2006; b) N-Heterocyclic Carbenes in Transition Metal Catalysis (Ed.: F. Glorius), Topics in Organometallic Chemistry, Springer Verlag, 2006.
[3] Tukov, A. A.; Normand, A. T.; Nechaev, M. S. Dalton Trans. 2009, 7015.
[4] Pour des exemples rapportés de complexes métalliques basés sur des ligands 2-pyridylidènes, voir : (a) Strong, E. T. J.; Price, J. T.; Jones, N. D. Dalton Trans. 2009, 9123. (b) Roselló-Merino, M.; Díez, J.; Conejero, S. Chem. Commun. 2010, 46, 9247. (c) Hata, K.; Segawa, Y.; Itami, K. Chem. Commun. 2012, 48, 6642. (d) Huang, Y.; Brown, M. K. Angew. Chem. Int. Ed. 2019, 58, 6048. Pour des applications en catalyse de complexes métalliques basés sur les 2-pyridylidènes,voir : (e) Hata, K.; Ito, H.; Segawa, Y.; Itami, K. Beilstein J. Org. Chem. 2015, 11, 2737. (f) Huang, Y.; Bergmann, A. M.; Brown, M. K. Org. Biomol. Chem. 2019, 17, 5913. (g) Trammel, G. L.; Kannangara, P. B.; Vasko, D.; Datsenko, O.; Mykhailiuk, P.; Brown, M. K. Angew. Chem. Int. Ed. 2022, 61, e202212117.
[5] a) Bézier, D.; Sortais, J.-B.; Darcel, C. Adv. Synth. Catal. 2013, 355, 19; b) Riener, K.; Haslinger, S.; Raba, A.; Högerl, M. P.; Cokoja, M.; Herrmann, W. A.; Kühn, F. E. Chem. Rev. 2014, 114, 5215; c) Liang, Q.; Song, D. Chem. Soc. Rev. 2020, 49, 1209.