[Seminar] International seminar about green and low-carbon catalysis

2019-10-23

Venue: Meeting Room on 4F, Shaw Engineering Building
Time: 
Monday, October 28, 8:30-13:00

Topic 1: Green Catalytic cross-couplings from C–H bonds for fast modifications of P and N ligands
Speaker: Prof. Pierre. H. Dixneuf (Université de Rennes 1)
Time: 8:40-9:25
[Abstract]
Ruthenium(II) catalysts associated to a carboxylate partner are able to promote the selective sp2 C–H bond activation of functional arenes and heterocycles to selectively lead to cross-couplings with  hetero(aryl) halides. It is possible now to perform such processes in water in a greener and more sustainable way without surfactant and with higher catalyst activity. The lecture will present several new aspects based on these activation principles. (1) Catalytic sp2 C–H bond activation/functionalization in water can be directed to produce polyheterocycles ligands and Hexaheteroarylbenzenes, with potential as polydentate ligands and for photocatalysis. (2) C(sp3) –H bond functionalization of alkyl goups linked to heterocycles are selectively achieved using simple copper catalysts and in situ generated radicals. (3) Ruthenium-catalyzed alkylations of ortho C–H bonds of phosphine oxides with alkenes can give access to new bifunctional phosphines. (4) Rhodium(I) catalyst can regioselectively functionalize the biaryl group of phosphines at o’ position via formal insertion of alkene to produce functional dialkylated phosphines. (5) The later can be used for efficient carboxylation of arylbromides with CO2. And help of photocatalyst. These green catalytic processes offer new routes for the building of polyfunctional ligands which have potential for the creation of efficient catalysts and for the design of new photoredox systems.


Topic 2: Precious catalysis with non-noble metal catalysts
Speaker: Prof. Matthias Beller (Leibniz Institute for Catalysis)
Time: 9:25-10:10
[Abstract]
The cost-effective and waste-free synthesis of materials, life science goods and all kinds of organic products require efficient chemical transformations. In this regard, development of more active and selective catalysts constitutes a key factor for achieving improved processes and providing the basis for sustainable chemical industry. Despite continuous advancements in all areas of catalysis, still organic syntheses as well as the industrial production of most chemicals can be improved significantly in terms of sustainability and efficiency. In the talk, it will be shown how new and improved homogeneous and heterogeneous catalysts can be developed by learning from each other. Specifically, the phenomenon of cooperative catalysis will be addressed in the context of non-noble metal-based catalysts. In detail, it will be demonstrated that recently developed molecular-defined as well as nano-structured cobalt and iron catalysts enable catalytic (de)hydrogenation processes with high yields and unprecedented selectivity. Examples which demonstrate the potential of such catalytic processes with bio-relevant metal complexes compared to more traditional catalytic reactions will also include reactions for energy technologies.


Topic 3: Site-specific and enantioselective cyanation of Sp3 C–H bonds 
Speaker: Prof. Guosheng Liu (Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences)
Time: 10:10—10:55
[Abstract]
Due to the highly active radical intermediate, the organic transformations via radical pathway have been extensively studied. However, the selective control of radical intermediate is extremely challenging, which significantly retards the success of highly selective radical reaction, especially for the enantioselective version. Recently, Our group recently reveals that the stereoselective control of radical could be achieved by using copper catalyst, and a series of enantioselective difunctionalization of alkenes have been explored by using bisoxazoline (Box)/Cu(I) catalytic system, such as trifluoromethylcyanation, aminocyanation, trifluoromethylarylation. In these studies, a benzylic radical intermediate was involved in the catalytic cycles, which can be enantioselectively trapped by (Box)/CuII intermediate to produce enantiomerically enriched products. Inspired these results, we disclosed a radical delay process for the successful asymmetric oxidative cyanation of benzylic C–H bond by using copper catalyst, which presented one of most efficient method for the efficient synthesis of optical pure alkylnitriles from simple alkyl arenes. Very recently, a site-specific and enantioselective allylic C–H cyanation was disclosed by an unprecedented copper-bound N-centered radicals, which will be presented as well.


Topic 4: Asymmetric hydrogenation using chiral tridentate ligands 
Speaker: Prof. Xumu Zhang (Southern University of Science and Technology)
Time: 10:10—10:55
[Abstract]
Catalytic asymmetric hydrogenation of prochiral ketones is a convenient and economical method to prepare chiral alcohols, which are significant building blocks in pharmaceuticals and natural products. Since Noyori’s milestone work in the 1990s wherein the BINAP-ruthenium-diamine catalytic system was originally developed for hydrogenation of ketones, numerous ligands including bidentate and tridentate ligands have been synthesized and investigated in metal catalyzed asymmetric hydrogenation. Because of the stability and high activity, tridentate ligands have shown promising potential in ketone reduction. In 1998, we had developed a novel tridendate NNN ligand (ambox) which had been successfully used in asymmetric transfer hydrogenation of ketones, which represents the first application of a tridendate ligand in asymmetric (transfer) hydrogenation.[1] Since then, chiral tridendate ligands have attracted increasing attention in highly efficient and enantioselective ketone hydrogenation. In 2010, indan-ambox, a derivative of ambox, had been applied in asymmetric hydrogenation of ketones with excellent enantiocontrol albeit with low efficiency.[2] To solve the efficiency problem, our group has recently developed a series of ferrocene-based tridentate ligands, f-amphox, [3] f-amphol,[4] f-ampha,[5] and f-amphamide, [6] which had shown super activity in iridium-catalyzed asymmetric hydrogenation of ketones (TONs up to 1000000). Compared to Noyori’s BINAP-ruthenium-diamine catalytic system, iridium (III)-hydride complex ligated with theses tridentate ligands have several features, including (1) extreme stability because of d6 configuration of Ir (III); (2) extreme activity because of the two Ir-H trans effect; (3) devoid of product inhibition due to coordinative saturation.


Topic 5: Synthesis of phosphorus-containing ligands and their applications in asymmetric catalysis
Speaker: Prof. Liqin Qiu (Sun Yat-sen University)
Time:
12:00-12:30
[Abstract]
Phosphorus-containg ligands are very important in modern organic synthesis and catalysis. In recent years, we successfully developed several kinds of chiral monophosphine and phosphoramidite ligands based on chiral-bridged biphenyl backbones and their applications in palladium-catalyzed asymmetric Suzuki coupling, iridium-catalyzed asymmetric addition of arylboronic acids to N-protected isatins and iridium-catalyzed enantioselective intramolecular allylic aminations of benzimidazole-tethered allylic carbonates with high efficiency. Impressively, the chiral-bridged biphenyl ligands with tunable dihedral angles exhibited obvious advantages over the BINOL-derived ligands in these explored transformations.



Announced by the School of Chemistry and Chemical Engineering


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