Jean-francois betzer - Academia.edu (original) (raw)

Papers by Jean-francois betzer

ChemInform, Jun 23, 2010

and Enynols: Regio-and Stereoselectivities.-The Pd-catalyzed hydrostannylation proceeds with high... more and Enynols: Regio-and Stereoselectivities.-The Pd-catalyzed hydrostannylation proceeds with high regio-and stereoselectivity which strongly depends on the substitution pattern of educt. The stannylcupration also proceeds with high regio-and stereoselectivity depending on reaction conditions as well as educt structure. However, modest selectivity is observed by radical reaction.-(BETZER,

Reaction Chemistry and Engineering, 2022

Piancatelli rearrangement of furyl carbinols is a relevant reaction to produce cyclopentenone der... more Piancatelli rearrangement of furyl carbinols is a relevant reaction to produce cyclopentenone derivatives. However, on large scale, Piancatelli rearrangement suffers several serious drawbacks such as long reaction period, high dilution conditions, moderate yields and the formation of dark brown polymeric materials. We described here the first use of Zippertex, an innovative technology reaching the subcritical water conditions (100-150 °C and 100 bars). In these conditions, this rearrangement proceeds smoothly to provide clean crude reaction mixtures without the formation of side-products and dark brown polymeric materials. Thus, a series of simple furyl carbinols directly obtained from bio-sourced furfural, and more challenging non-symmetrical furan-2,5-dicarbinol substrates, also obtained from bio-sourced raw material (HMF), were efficiently transformed into cyclopentenone derivatives in good yields. This technology could be applied successfully on challenging substrates substituted by an aliphatic group and also performed on 500 mmol scale. a.

European Journal of Organic Chemistry, Apr 7, 2021

https://icsn.cnrs.fr/ Supporting information for this article is given via a link at the end of t... more https://icsn.cnrs.fr/ Supporting information for this article is given via a link at the end of the document.

Comptes rendus de l'Académie des sciences, Aug 1, 2001

ABSTRACT

Elsevier eBooks, 2015

Chapter Outline 1. INTRODUCTION 2. SYNTHETIC APPROACH AND SYNTHETIC METHODS DEVELOPMENT 2.1. Reac... more Chapter Outline 1. INTRODUCTION 2. SYNTHETIC APPROACH AND SYNTHETIC METHODS DEVELOPMENT 2.1. Reactivity of an -Oxygenated Crotyltitanium 2.2. Reactivity of a Z-O-Enecarbamate Group 2.3. 1,2-Dyotropic Rearrangement of Dihydrofuran 3. TOTAL SYNTHESIS OF (+)-DISCODERMOLIDE (DDM) 3.1. Strategic Considerations 3.2. Preparation of C8-C14 Subunit B 3.3. Preparation of C15-C24 Subunit A 3.4. Preparation of C1-C7 Subunit C 3.5. Completion of Total Synthesis of DDM 4. CONCEPTION, SYNTHESIS AND BIOLOGICAL EVALUATION OF DDM-ANALOGUES 4.1. Conformation of DDM and Conception of Analogues 2 4.2. Modification of Terminal Diene C15-C24 Part 4.3. Modification of the Trisubstituted C13-C14 Double Bond 4.4. Modification of C1-C5 Lactone Part 4.5. Biological Evaluation of Synthetic Analogues 5. CONCLUSION Acknowledgements References

Organic chemistry frontiers, 2021

Substituted and non-symmetrical furan-2,5-dicarbinols were readily prepared from hydroxymethylfur... more Substituted and non-symmetrical furan-2,5-dicarbinols were readily prepared from hydroxymethylfurfural (HMF), a renewable raw material from biomass. The Piancatelli rearrangement of these furan-2,5-dicarbinols, catalyzed by DyCl3 and under microwave activation, affords 5-substituted-4-hydroxymethyl-4-hydroxycyclopentenones in a regio-and diastereoselective manner. This methodology can be extended to aza-Piancatelli type reactions by using nitrogen nucleophiles, to furnish the corresponding aminocyclopentenone derivatives. These synthetized bis-hydroxylated cyclopentenone derivatives exhibited significant cytotoxicity against eight human tumor cell lines.

Advanced Synthesis & Catalysis, Jul 11, 2018

This manuscript discloses the first uses of chiral phosphates based on C2-symmetric paracyclophan... more This manuscript discloses the first uses of chiral phosphates based on C2-symmetric paracyclophane scaffolds as chiral counterions in transition metal catalysis, showing that they may compare favorably with other known chiral phosphates, such as the TRIP phosphate. The targeted catalytic reaction is a silver(I) promoted domino heterocyclization of 2-(1-alkynyl)-2-alken-1-one derivatives, in the presence of C-, or N-nucleophiles, which provides an efficient access to substituted bicyclic furans. Results show that high levels of enantioselectivity can be attained with either paracyclophanebased phosphates or TRIP phosphates, when the nucleophilic reactants display N-H functions in appropriate positions, near to the nucleophilic center. Therefore, the involvement of H-bonding between the NH function and the phosphate in the enantiodetermining step is postulated.

Chemistry: A European Journal, Jul 26, 2011

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Journal of Organic Chemistry, Feb 9, 2018

The enantioselective H-transfer hydrogenation of quinoline by Hantzsch ester is a relevant exampl... more The enantioselective H-transfer hydrogenation of quinoline by Hantzsch ester is a relevant example of Brønsted acid catalyzed cascade reactions, with phosphoric acid being privileged catalysts. The generally accepted mechanism points out the hydride transfer step as the rate-and stereo-determining step, however computations based on these models do not totally fit with experimental observations. We hereby present a computational study that enlightens the stereochemical outcome and quantitatively reproduces the experimental enantiomeric excesses in a series of H-transfer hydrogenations. Our calculations suggest that the high stereocontrol usually attained with BINOL-derived phosphoric acids results mostly from the steric constraints generated by an aryl substituent of the catalyst, which hinders the access of the Hantzsch ester to the catalytic site and enforces approach through a specific way. It relies on a new model involving the preferential assembly of one of the stereomeric complexes formed by the chiral phosphoric acid and the two reaction partners. The stereodetermining step thus occurs prior to the H-transfer step.

Tetrahedron, Nov 1, 1996

Absrrucr : Title compounds were prepared by the intramolecular cyclisatlon of 4-aminocycloheptano... more Absrrucr : Title compounds were prepared by the intramolecular cyclisatlon of 4-aminocycloheptanones as the key step. The functionalisation of the iron-complexed uopone gave cyclohepta-1,3-dienes. The 4-aminocycloheptanones result from a heterocycloaddition between an acylnitroso compound and a cyclohepta-1.3.diene.

Chemistry: A European Journal, Feb 2, 2016

The key structural feature of the new phosphoramidites is a paracyclophane scaffold in which two ... more The key structural feature of the new phosphoramidites is a paracyclophane scaffold in which two aryl rings are tethered by both a 1,8-biphenylene unit and a O-P-O bridge. Suitable aryl substituents generate planar chirality. The corresponding gold(I) complexes promote the cycloisomerization of prochiral nitrogentethered dienynes. These reactions afford bicyclo[4.1.0]heptene derivatives displaying three contiguous stereogenic centres, with very high diastereoselectivity and up to 95% ee. Supporting information for this article is given via a link at the end of the document.

Advanced Synthesis & Catalysis, Feb 11, 2011

A new synthetic approach to hexahydroisoindol-4-ones is reported, based on the formal [3+2] cycli... more A new synthetic approach to hexahydroisoindol-4-ones is reported, based on the formal [3+2] cyclization reaction between N-arylsulfonylimines and cyclic conjugated dienes, under phosphine catalysis. Key substrates are 3-vinylcyclohex-2-enones with electronwithdrawing substituents (ester, amido, cyano, phosphoryl and keto groups) on the exocyclic double bond, which afford the three atom synthons for the construction of the pyrroline ring. Total syn stereoselectivity is observed in these annulations. The scope of the reaction has been demonstrated and mechanistic issues are considered, based on deuteration experiments and DFT calculations.

Journal of Organic Chemistry, Oct 6, 2014

Phosphoric acids with planar chiral paracyclophane scaffolds have been prepared in optically pure... more Phosphoric acids with planar chiral paracyclophane scaffolds have been prepared in optically pure form starting from 1,8-dibromobiphenylene, by means of a chiral phosphorodiamidate as the phosphorylating agent. Structural characterization and configurational assignment have been performed by X-ray diffraction studies. The acids promote the organocatalytic enantioselective Htransfer reduction of -arylquinolines with up to 90% enantiomeric excess.

Bioconjugate Chemistry, May 17, 2016

Chemistry: A European Journal, Dec 8, 2008

Elsa de Lemos, [a] François-Hugues Porée, [a] Arnaud Bourin, [a] Julien Barbion, [a] Evangelos Ag... more Elsa de Lemos, [a] François-Hugues Porée, [a] Arnaud Bourin, [a] Julien Barbion, [a] Evangelos Agouridas, [a] Marie-Isabelle Lannou, [a] Alain Commerçon, [b] Jean-François Betzer,* [a] Ange Pancrazi,* [a] Janick Ardisson* [a]

Journal of Organic Chemistry, Oct 1, 1997

Different enynols and propargyl derivatives were sumitted to radical hydrostannylation (Bu 3 SnH/... more Different enynols and propargyl derivatives were sumitted to radical hydrostannylation (Bu 3 SnH/ AIBN), Pd(0)-catalyzed hydrostannylation [Bu 3 SnH/Pd(0)], and stannylcupration [Bu 3 Sn(R)CuCNLi 2 ] conditions. Except for the radical stannylation reaction, high regio-and stereoselective formation of vinyl-and dienylstannanes are obtained. Results are tentatively explained in terms of steric Interactions between the alkyne or enyne substituents and the palladium or cuprate moieties in the different reaction intermediates.

Encyclopedia of Reagents for Organic Synthesis, Oct 20, 2014

HAL (Le Centre pour la Communication Scientifique Directe), Apr 28, 2022

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.