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Séminaire Chimie ED459

Polyfunctional Li-, Mg- and Zn- organometallics in organic synthesis

Prof. Paul Knochel (Department of Chemistry, Ludwig-Maximilians-Universität, Munich, Germany)

publié le

Le Jeudi 15 décembre 2016 à 14h
ENSCM, Amphithéâtre de Forcrand

First, we will describe a new general method for preparing chiral secondary alkyllithium reagents using a stereoselective I/Li-exchange reaction. This chemistry will be used to prepare the natural occurring pheromone (–)-lardolure in a very predictive manner (Scheme 1).

We will then describe new efficient direct insertion procedures of zinc to aromatic and heterocyclic halides and use these methods to prepare a range of polyfunctional organozinc reagents. By using a directed ortho C–H activation triggered by TMPZnOPiv, we will be able to prepare zinc reagents having an air- and moisture-enhanced stability and show their utility in organic synthesis (scheme 2).

We will also report a new quite general cobalt-catalyzed cross-coupling procedure allowing the preparation of various unsaturated molecules. Notice that the catalyst used CoCl2 is 1000 times cheaper then PdCl2 generally used in cross-couplings (Scheme 3).

Finally, we will demonstrate that organozinc and organomagnesium reagents are compatible with various strong Lewis acids. This can be applying to achieve unusual metalations. The use of flow-technology further extends the reaction scope (Scheme 4).

Key references

1. Greshock T.J., Moore K.P., McClain R.T., Bellomo A., Chung C.K., Dreher S.D., Kutchukian P.S., Peng Z., Davies I.W., Vachal P., Ellwart M., Manolikakes S.M., Knochel P., Nantermet P.G., Angew. Chem. Int. Ed. 2016, 55, 13714–13718.
2. Benischke A. D., Leroux M., Knoll I., Knochel P., Org. Lett. 2016, 18, 3626–3629.
3. Haas D., Hammann J. M., Lutter F.H., Knochel P., Angew. Chem. Int. Ed. 2016, 55, 3809–3812.
4. Ellwart M., Makarov I.S., Achrainer F., Zipse H., Knochel P., Angew. Chem. Int. Ed. 2016, 55, 10502–10506.
5. Morozova V., Moriya K., Mayer P., Knochel P. Chem. Eur. J. 2016, 22, 9962–9965.
6. Hammann J.M., Haas D., Knochel P., Angew. Chem. Int. Ed. 2015, 54, 4478–4481.
7. Ellwart M., Knochel P., Angew. Chem. Int. Ed. 2015, 54, 10662–10665.

Contact local ICGM : Dr. Marc Taillefer, D.R. CNRS (équipe AM2N)

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