Domino reactions: Cu(I)-Catalyzed Michael addition/aldolisation reactions
For several years, our laboratory has developed methodologies involving the transfer of hydrides, silicon-based and boron-based nucleophiles using copper(I) catalysts. More specifically, domino processes such as copper(I)-catalyzed Michael addition/aldolisation have been the subject of intensive work during the last years. These developments using readily available Michael acceptors, pronucleophiles and electrophiles led to the chemo- and stereoselective syntheses of highly functionalized aldol adducts.
Representative publications :
- Deschamp, J.; Chuzel, O.; Hannedouche, J.; Riant, O.; Angew. Chem. Int. Ed. 2006, 45, 12921297
- Chuzel, O.; Deschamp, J.; Chausteur, C.; Riant, O.; Org. Lett. 2006, 8, 59435946
- Welle, A.; Petrignet, J.; Tinant, B.; Wouters, J.; Riant, O., Chem. Eur. J. 2010, 16, 1098010983
- Welle, A.; Cirriez, V.; Riant, O.; Tetrahedron, 2012, 68, 34353443
Cu(I)-Catalyzed 1,2-addition of nucleophilic silicon to carbonyl compounds
More recently, we turned our attention toward other applications of copper(I) catalysis in the field of pronucleophiles activation. For example, next to the copper-catalyzed 1,4-addition of silicon-based pronucleophiles, we envisioned to use such reagents in a 1,2-addition process on carbonyl compounds. Using this strategy, we developed a straightforward synthesis of acylsilane and enantioenriched α-hydroxysilanes from anhydrides and aldehydes respectively.
Related publications :
- Cirriez, V.; Rasson, C.; Hermant, T.; Petrignet, J.; Diaz Alvarez, J.; Robeyns, K.; Riant, O. Angew. Chem. Int. Ed. 2013, 52, 17851788
- Cirriez, V.; Rasson, C.; Riant, O. Adv. Synth. Catal. 2013, 355, 31373140
Cu(I)-Catalyzed cross-coupling of vinylsilanes with electrophiles
Beside the development of silicon-containing compounds syntheses, we were also interested in studying the reactivity of vinylsilanes in the presence of a copper catalyst. Efficient coupling methods with several electrophiles were elaborated, allowing the synthesis of valuable building blocks, such as 1,4-dienes, allylbenzene derivatives and enynes.
Related publications :
- Cornellisen, L.; Vercruysse, S.; Sanhadji, A; Riant, O. Eur. J. Org. Chem. 2014, 3538
- Cornelissen, L.; Cirriez, V.; Vercruysse, S.; Riant, O. Chem. Commun. 2014, 50, 80188020
- Cornelissen, L.; Lefrancq, M.; Riant, O. Org. Lett. 2014, 16, 30243027
Tandem reactions: Cu(I)-Catalyzed nucleophilic addition/Pd(0)-catalyzed electrophilic allylation
Due to our successful attempts to react in situ generated organocopper species with aldehydes, we envisioned to extend the scope of this strategy by using a π-allyl palladium species as the electrophilic partner. Therefore, we recently reported the enantioselective 1,4-reduction/allylation of enones, thanks to a Cu(I)/Pd(0) cooperative catalysis system. Similarly, the stereoselective synthesis of tetrasubstituted vinylsilanes by the 1,4-silylation/allylation of ynoates was developed.
Representative publications :
- Nahra, F.; Macé, Y.; Lambin, D.; Riant, O. Angew. Chem. Int. Ed. 2013, 52, 32083212
- Vercruysse, S.; Cornelissen, L.; Nahra, F.; Collard, L.; Riant, O. Chem. Eur. J. 2014, 20, 18341838
Development of new copper(I) catalysts: mechanistic studies and applications (in collaboration with Prof. T. Leyssens, UCL)
The development of efficient and stable copper(I) catalysts remains a large research area in our group. During the last years, we focused on the synthesis of air-stable copper(I) catalysts containing the bifluoride counteranion HF2-. Associated with NHC-Cu or diphosphine-Cu complexes, this counter-anion was found to improve the catalytic properties in terms of activation and reactivity.
Representative publications:
- Vergote, T.; Nahra, F., Welle, A.; Luhmer, M.; Wouters, J.; Mager, N.; Riant, O.; Leyssens, T. Chem. Eur. J. 2012, 18, 793798
- Vergote, T.; Nahra, F., Peeters, D.; Riant, O.; Leyssens, T. J. Organomet. Chem. 2013, 730, 95103
- Cirriez, V.; Rasson, C.; Hermant, T.; Petrignet, J.; Diaz Alvarez, J.; Robeyns, K.; Riant, O. Angew. Chem. Int. Ed. 2013, 52, 17851788
Supported catalysis: Heterogenization of homogenous catalysts on nanocarbons and silica (in collaboration with Prof. S. Hermans, A. Jonas, B. Nysten, UCL)
In addition to our developments in the field of homogeneous catalysis, our group has more recently contributed to the design and elaboration of supported transition metal-based catalysts on supports such as silica or nanocarbons. These projects are carried out in collaboration with the groups of Prof. Sophie Hermans, Prof. Alain Jonas and Prof. Bernard Nysten from UCL.
At first, our group aims to develop methods in order to anchor organic ligands on carbon nanotubes and graphene, in order to immobilize transition metals on them. In this purpose, literature-known or original methods were studied.
Related publication:
- Vriamont, C.; Devillers, M. ; F.; Riant, O.; Hermans, S. Chem. Commun. 2013, 49, 1050410506
Pyrene-containing phosphine gold cluster were non-covalently deposited on carbon nanotubes by π-π stacking interactions. After thermal activation, the obtained metal nanoparticles turned out to be efficient supported catalysts for the cinnamaldehyde hydrogenation with good selectivity and recyclability.
Related publication:
- Vriamont, C.; Haynes, T.; McCargueMurphy, E.; Pennetreau, F.; Riant, O.; Hermans, S. J. Catal. 2015, 329, 389400
Our group also focused on the covalent linkage of organic moieties on nanocarbon by using radical chemistry based on the xanthate functional group. Post-functionalization of the anchored species allowed the incorporation of phosphines on the surface, which could then be used as ligands for transition metal catalysts.
Representative publications:
- Vanhorenbeke, B.; Vriamont, C.; Pennetreau, F.; Devillers, M.; Riant, O.; Hermans, S. Chem. Eur. J. 2013, 19, 852856
- Pennetreau, F.; Riant, O.; Hermans, S. Chem. Eur. J. 2014, 20, 1500915012
The covalent anchoring of homogeneous catalysts on silica has also been studied. Terpyridine ligands possessing a silicon-based moiety to allow the immobilization on silica were prepared. Palladium complexes could be formed on the surface by coordination with the anchored tridentate ligands. The catalytic activity was evaluated using a π-allyl palladium-involved reaction in order to form a coumarin-based fluorophore. It was demonstrated that the activity of the immobilized catalyst was superior to the homogeneous control reactions.
Related publications:
- Fernandes, A. E.; Devillez, S.; d’Haese, C.; Deumer, G.; Haufroid, V.; Nysten, B.; Riant, O.; Jonas, A. M. Langmuir, 2012, 28, 1482214828
- Fernandes, A. E.; Hensenne, P.; Mathy, B.; Guo, W.; Nysten, B.; Jonas, A. M.; Riant, O. Chem. Eur. J. 2012, 18, 788792
Besides, the anchoring of transition metal complexes was carried out by using a copper(I)-catalyzed alkyne-azide cycloaddition to link the metal complex with the anchoring moiety.
Related publications:
- Fernandes, A. E., Jonas, A. M.; Riant, O. Tetrahedron 2014, 70, 17091731
- Fernandes, A. E.; Ye, Q.; Collard, L.; Le Duff, C.; d’Haese, C., Deumer, G., Haufroid, V.; Nysten, B.; Riant, O.; Jonas, A. M. ChemCatChem, 2015, 7, 856864