Vabilo na Preglov kolokvij / Invitation to the Pregl Colloquium, 5. 6. 2014

[Brigita Pirc]

VABILO NA PREGLOV KOLOKVIJ /  INVITATION TO THE PREGL COLLOQUIUM


Dr. Dominique Cahard
UMR 6014 CNRS COBRA, University et INSA de Rouen, 76821 Mont St. Aignan, France; E-mail: dominique.cahard at univ-rouen.fr<mailto:dominique.cahard at univ-rouen.fr>

Četrtek, Thursday, 5. 6. 2014, ob / at 13h
Velika predavalnica Kemijskega inštituta / Lecture Hall at the National Institute of Chemistry; Hajdrihova 19, Ljubljana

Enantioselective Metal-Catalyzed Hydrogen Transfer Reactions for the Construction of CF3-bearing Stereogenic Carbons
The synthesis of enantiopure molecules featuring a trifluoromethyl motif at a stereogenic carbon centre increasingly stimulates high interest in many laboratories. Such compounds can be approached by direct introduction of the CF3 group or by exploitation of prochiral trifluoromethylated substrates.[1] The stereoselective construction of all-C tertiary CF3-bearing stereogenic carbon centres without any heteroatom substituent undoubtedly belongs to the most fundamental topics in fluorine chemistry and remains highly challenging. As tool for this purpose, we have investigated the ruthenium catalyzed redox isomerization of trifluoromethylated allylic alcohols to access enantioenriched *-trifluoromethyl carbonyl compounds. The catalytic redox isomerization is an efficient, selective, atom-economic, one-step process for isomerization of C=C bond of O-allylic substrates into saturated carbonyl compounds.[2] In this method, a transition metal assists the migration of the carbon-carbon double bond into an enol which tautomerizes to the carbonyl compound. It is a conceptually attractive approach, which compares favorably with the more conventional sequential two-step oxidation and reduction reactions. Several issues were addressed during the search for optimal reaction conditions and will be detailed in the lecture. It includes (a) the choice of the catalyst, (b) the impact of the highly electron-withdrawing CF3 group: electronic, steric, and position effects, (c) the gain of mechanistic insights, and (d) the stereocontrol of the newly created stereogenic centre.[3]
[1] (a) J.-A. Ma, D. Cahard, Chem. Rev. 2008, 108, PR1-PR43. (b) J. Nie, H.-C. Guo, D. Cahard, J.-A. Ma, Chem. Rev. 2011, 111, 455-529.
[2] (a) R. Uma, C. Crévisy, R. Grée, Chem. Rev. 2003, 103, 27-51. (b) L. Mantilli, C. Mazet, Chem. Lett. 2011, 40, 341-344.
[3] (a) V. Bizet, X. Pannecoucke, J.L. Renaud, D. Cahard, Angew. Chem. Int. Ed. 2012, 51, 6467-6470. (b) D. Cahard, V. Bizet, X. Dai, S. Gaillard, J.L. Renaud, J. Fluorine Chem. 2013, 155, 78-82. (c) V. Bizet, X. Pannecoucke, J.L. Renaud, D. Cahard, Adv. Synth. Catal. 2014, 355, 1394-1402.


Vljudno vabljeni! / Kindly invited!

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