Publications 2015

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PUBLICATIONS

New J. Chem. 2015, 39, 9504-9517

Multi-nuclear NMR of axially chiral biaryls in polypeptide orienting solvents: spectral discriminations and enantiorecognition mechanisms

P. Berdagué, J.-E. Herbert-Pucheta, V. Jha, A. Panossian, F. R. Leroux, P. Lesot

In this work, we show how several multi-nuclear 1D/2D-NMR techniques using homopolypeptide chiral liquid crystals as aligning solvents can provide a panel of analytical possibilities to spectrally discriminate enantiomers of a large collection of trisubstituted axially chiral biphenyls. Approaches involving 31P, 13C and 2H 1D- or 2D-NMR experiments at natural abundance levels are explored. Among noteworthy results, the first examples of spectral enantioseparations using 31P nuclei as nuclear probe are reported. Finally, the roles of electronic factors and shape anisotropy in the efficiency of chiral discrimination mechanisms are examined and discussed.

Org. Lett. 2015, 17, 4510-4513

In Situ Generated Fluorinated Iminium Salts for Difluoromethylation and Difluoroacetylation

E. Schmitt, B. Rugeri, A. Panossian, J.-P. Vors, S. Pazenok, F. R. Leroux

The use of TFEDMA, a fluoroalkyl amino reagent, for the difluoromethylation and difluoroacylation of arenes, heteroarenes, and C–H acidic compounds is reported. This approach allows for an efficient access to difluoromethylated products of high added value in good to excellent yields and with scale-up possibilities.

Eur. J. Org. Chem. 2015, 6515-6525

Modular Synthesis of Biaryl‐Substituted Phosphine Ligands: Application in Microwave‐Assisted Palladium‐Catalyzed C–N Cross‐Coupling Reactions

C. Singh, J. Rathod, V. Jha, A. Panossian, P. Kumar, F. R. Leroux

Biarylmonophosphine ligands have been synthesized by “ARYNE” cross‐coupling reaction of aryllithiums with 1,2‐dibromobenzene and subsequent regioselective functionalization. These ligands were employed in Pd‐catalyzed C–N bond formation. A wide variety of amines were successfully coupled with an array of halobenzenes under microwave irradiation to give the expected products in good to excellent yields. A number of biaryl-phosphine ligands showed that steric bulk and electronic properties of substituents on phosphorus play a crucial role in the catalytic activity of C–N cross‐couplings.

Eur. J. Org. Chem. 2015, 6052-6060

A General Approach towards NH‐Pyrazoles That Bear Diverse Fluoroalkyl Groups by Means of Fluorinated Iminium Salts

E. Schmitt, G. Landelle, J.-P. Vors, N. Lui, S. Pazenok, F. R. Leroux

A new and general approach to important fluoroalkyl‐substituted pyrazoles has been developed. The approach is based on the use of FARs and their Lewis acid activation to form a fluoroalkyl iminium salt that acts as a formal “fluoroacyl transfer reagent”. Their interaction with readily available fluoroalkyl azines followed by spontaneous cyclization of the formed intermediates under acidic conditions leads to the formation of 3,5‐disubstituted pyrazoles. The reaction is extremely versatile, high yielding, and allows quick access to pyrazoles that bear two fluoroalkyl functionalities otherwise difficult to prepare. The reaction is scalable and suitable for industrial production.

Tetrahedron Lett. 2015, 56, 5112-5115

Synthesis and biological evaluation of new nucleosides derived from trifluoromethoxy-4-quinolones

K. Plevová, K. Briestenská, F. Colobert, J. Mistríková, V. Milata, F. R. Leroux

The synthesis of new nucleoside derivatives from 6- and 7-trifluoromethoxy-4-quinolones is described. The present synthesis is a combination of the Gould–Jacobs reaction for the preparation of 4-quinolones and a modified Vorbrüggen reaction for the construction of nucleoside derivatives. The target compounds were tested against murine gammaherpesvirus MHV-68 type.

Adv. Synth. Catal. 2015, 357, 2833-2839

Asymmetric Bromine–Lithium Exchange: Application toward the Synthesis of New Biaryl‐Diphosphine Ligands

J. Graff, E. Łastawiecka, L. Guénée, F. Leroux, A. Alexakis

The desymmetrization of the prochiral tetrabromobiphenyl via asymmetric bromine–lithium exchange as a key step of synthesis of novel biphenyl‐diphosphine ligands is reported. This new approach allows an easy access to twelve new enantiomerically pure atropisomeric ligands in one‐ to three‐step reactions in good to excellent yields.

Chem. Soc. Rev. 2015, 44, 3418-3430

Recent advances and new concepts for the synthesis of axially stereoenriched biaryls

J. Wencel-Delord, A. Panossian, F. R. Leroux, F. Colobert

Axial chirality is a key feature of many important organic molecules. Significant efforts in the field of the atropisomeric synthesis of biaryls have hence been undertaken over the past decade. Several major improvements of already known methods to build up such chiral backbones have been achieved and, in parallel, novel concepts have emerged enabling unprecedented synthetic routes toward molecules of this kind. These outstanding steps further unlocked the door to the preparation of previously difficult-to-access precursors of privileged ligands like BINOL, BINAM, QUINAP and many others.

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