Professor Janine Cossy
​Title: The Power of Transition Metals. Construction and Functionalization of Heterocycles
Abstract: Heterocycles are present in a great diversity of natural products and/or bioactive compounds. They are also present in ligands, dyes, materials, etc. Due to the importance of heterocycles, it is important to develop efficient and versatile chemoselective methods to access these compounds. In this lecture, different methods will be presented to acess functionalized heterocycles containing oxygen and nitrogen. Depending on the synthetic target to be reached, we will show that transition metals such as gold, iron, cobalt or rhodium are excellent synthetic tools to realize either the functionalization and/or the construction of heterocycles.
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Abstract:
Professor Ruben Martin
​Title: Ni-catalyzed functionalization of remote sp3 C–H bonds
Abstract: In recent years, chemists have been challenged to design new catalytic methodologies for converting (un)saturated hydrocarbons into value-added products by means of catalytic sp3 C-H functionalization. However, the ability to enable catalytic C-C bond-formation from a simple hydrocarbon is not particularly straightforward, as sp3 C-H bonds are less acidic and lack proximal empty low-energy or filled high-energy orbitals that interact with the d orbitals of the transition metal. Indeed, saturated hydrocarbons rank amongst the least reactive molecules, and their inertness is somewhat reflected by the forcing conditions that are required in the very few alkane transformations performed in industry, for example the cracking or reforming processes in oil refineries using heterogeneous catalysts operating at temperatures of approximately 400 to 600 ºC. Additionally, we should take into consideration site-selectivity principles due to the presence of multiple, yet similar, sp3 C-H bonds within the alkyl side chain. Recently, our group has developed a series of Ni-catalyzed reactions that enable the functionalization of remote sp3 C-H bonds in both saturated and unsaturated hydrocarbons via a formal dynamic displacement of the catalyst throughout the alkyl side-chain. These transformations are characterized by its simplicity, generality and modularity, thus increasing our ever-growing arsenal for converting simple precursors into added-value chemicals.
Professor Karol Grela
​Title: Tuning of neutral carbene ligands—the way to control activity, selectivity and stability of ruthenium olefin metathesis catalysts
Abstract: Ruthenium-catalyzed olefin metathesis reactions represent an attractive and powerful transformation for the formation of new carbon-carbon double bonds [1]. This area is now quite familiar to most chemists as numerous catalysts are available that enable a plethora of olefin metathesis reactions. However, formation of substituted and crowded double bonds, decreasing the amount of metal, using metathesis in medicinal chemistry, etc. still remain a challenge, making industrial applications of this methodology difficult [1]. These limitations can be solved by designing new, more active and stable catalysts. Sometimes even a small alteration of the catalyst's structure can lead to a visible change of its properties. This was the case in the so-called Grubbs’ second generation ruthenium catalysts featuring neutral N-Heterocyclic Carbene (NHC) ligands [2,3]. Such NHC ligands typically contain large N-alkyl or N-aryl groups (sometimes called “wings” or “arms” of the NHC ligand). During the lecture some examples of possible structural modifications of the NHC ligands will be presented, mostly based on adjusting the relative size of these N-groups [3,4] or by limiting their free movement [5]. Such alterations of the aromatic “wings” in the NHC ligand can be used to affect the resulted ruthenium olefin metathesis catalyst’s activity, selectivity and stability.
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References
[1] Olefin Metathesis: Theory and Practice, Grela, K. (Ed.), John Wiley & Sons, 2014.
[2] C. Samojłowicz, M. Bieniek, K. Grela, Chem. Rev. 109. (2009) 3708.
[3] L. Monsigny, A. Kajetanowicz, K. Grela, Chem. Rec. 21. (2021) 3648.
[4] S. Planer, P. Małecki, B. Trzaskowski, A. Kajetanowicz, K. Grela, ACS Catal. 10. (2020), 11394.
[5] W. Kośnik, D. Lichosyt, M. Śnieżek, A. Janaszkiewicz, K. Woźniak, M. Malińska, B. Trzaskowski,
A. Kajetanowicz, K. Grela, Angew. Chem. Int. Ed. (2022), e202201472.
Professor Tomislav Rovis
​Title: Controlling Catalysis with Visible Light
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Abstract: Visible light is an abundant energy source that can also be delivered on demand. Harnessing the energy in visible light has recently been accomplished through the use of photoredox catalysis, which can generate radical intermediates by an oxidation or reduction step to initiate a bond formation followed by a return of the electron or hole to close the catalytic cycle. We have been engaged in expanding the versatility of visible light photoredox catalysis and have uncovered strategies to effect C-H activation in unactivated positions of alkanes as well as controlling catalysis spatially and temporally. Reaction development, mechanistic investigations and synthetic applications will be the subject of this lecture.
Professor John Bower
​Title: Catalytic Chirality Generation: New Strategies for Organic Synthesis
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Abstract: Our group develops new catalysis platforms that enable the efficient generation of chiral building blocks and heterocyclic scaffolds. Current priority areas include: (i) the development of catalytic C-C bond activation processes and associated cycloadditions [1], (ii) the development of aza-Heck reactions [2], and (iii) the development of enantioselective alkene hydroarylation reactions [3]. Selected recent highlights will be presented.
Representative publications:
[1] Wang, G.-W.; Bower, J. F. J. Am. Chem. Soc. 2018, 140, 2743.
[2] Ma, X.; Hazelden, I. R.; Langer, T.; Munday, R. H.; Bower, J. F. J. Am. Chem. Soc. 2019, 141, 3356.
[3] Grélaud, S.; Cooper, P.; Feron, L. J.; Bower, J. F. J. Am. Chem. Soc. 2018, 140, 9351.
Professor Debabrata Maiti
​Title: Designing of templates to reach the distal C–H bond
Abstract: Mimicking the nature has always been a coveted target for scientific communinities. A precise understanding has emerged as to how enzymes accomplish the chemical transformations. Enzymes catalyze inert C-H bond functionalization in a regio- and stereoselective manner using metal-active site. Inspired by the nature, we have developed catalytic methods to functionalize carbon–hydrogen (C–H) bonds which provides significant economic and environmental benefits over traditional synthetic methods. Applicability of our strategies towards synthesis of various complex molecules will be discussed.
Professor Jared T. Shaw
​Title: Enantioselective C–H Insertion Reactions of Donor/Donor Carbenes for the Synthesis of Complex Natural Products
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Abstract: Rhodium carbenes lacking electron withdrawing groups, or “donor/donor” carbenes, participate in a wide variety of selective reactions. Due to the reduced electrophilicity, these reactive intermediates exhibit remarkable functional group tolerance, enabling access to uniquely complex organic molecules. The development of new methods and their application to the synthesis of a series of complex heterocycles, including several natural products, will be described.
Professor Pauline Chiu
​Title: Cycloadditions for Assembling Cycloheptanoids Towards the Synthesis of Natural Products
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Abstract: To address the synthesis of natural products having a cycloheptanoid framework, we have been studying (4+3) and (5+2) cycloadditions to provide functionalized seven-membered carbocycles, and in enantiomerically enriched forms. In this lecture, we will report our results, and our attempts to apply them to the synthesis of various natural products.
Professor Diego Alves
​Title: Synthesis of highly functionalized 1,2,3-triazoles systems through copper- or organocatalysis protocols
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Abstract: This presentation will provide a comprehensive overview of reported methods particularly copper- and organocatalyzed reactions - for the regioselective syntheses of high functionalized 1,2,3-triazoles systems. These chemical entities are prevalent cores in biologically active compounds and functional materials. In view of their unique properties, substantial efforts have been paid for the design and development of practical approaches for the synthesis of these scaffolds.
Professor Annaliese Franz
​Title: Organosilicon Chemistry for Enantioselective Synthesis, Catalyst Design and Medicinal Chemistry
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Abstract: The successful development of new synthetic methods and catalysts is important for the discovery and production of chiral organic molecules and materials. This talk will highlight several examples of organosilicon chemistry that provide rich opportunities and applications for methodology, mechanism and novel synthetic targets. First, the development of enantioselective synthesis and molecular recognition components involved to access chiral-at-silicon molecules will be presented with applications for the design of new catalyst systems based on siloxy compounds. Second, the unique reactivity of allylsilane and allenylsilane nucleophiles will be featured to demonstrate opportunities to develop efficient methods for the enantioselective synthesis of complex molecules such as spirooxindoles, as well as interesting opportunities to explore mechanistic features of annulation reactions and Lewis acid-catalyzed reactions. Finally, examples for the synthesis of novel organosilicon targets with medicinal applications will be presented. For all studies, results of structural, mechanistic, kinetics and molecular binding studies will be included to provide insight for catalyst activity, design and synthetic applications.
Professor Elisa S. Orth
​Title: Imidazoles: promiscuous or versatile towards organophosphates?
Abstract: Is the broad mechanistic versatility of Imidazoles towards organophosphates, that has inspired many catalysts, beneficial or a threateningly promiscuity? We have been working on unravelling this puzzle and show how varying the nature of the organophosphate can lead to N-phosphorylation or unusual N-alkylation. Also, the structure of imidazole derivatives are evaluated, which also show an interesting trend. Should this add to the known versatility of Imidazole or can it be considered an unsought promiscuity? A concise understanding of the mechanism underlying organophosphates is imperative for effectively applying in real destruction or monitoring systems of agrochemicals. Preferably, one seeks less toxic products and no side reactions. Moreover, we show that one monitoring system may not apply to various toxic agrochemicals, since their structure can shift the mechanism, hence lead to different products and suppress important signals or give false positives.
Professor Daniel Werz
​Title: Carbopalladation Cascades – Not only syn, but also anti
Abstract: A characteristic feature of carbopalladation reactions is the syn-attack of the organopalladium species LnX[Pd]-R on the reacting π-system [1]. Such a step results in compounds bearing Pd and R on the same side of the originating alkene moiety. Embedded into longer domino sequences complex structures are efficiently obtained by a repetition of this syn-carbopalladation step. In this way, linear oligoynes were cyclized in a dumbbell-mode and led to benzene-type structures or higher oligoenes [1]. We exploited this chemistry to synthesize not only chromans, isochromans [2] and dibenzopentafulvalenes [3], but also to access the most truncated π-helicenes which only consist of a Z,Z,Z,..-oligoene chain that is fixed in an all s-cis arrangement [4]. All these domino processes are based on a syn-carbopalladation cascade. However, a carbopalladation cascade involving formal anti-carbopalladation steps opens new avenues to create compounds with tetrasubstituted double bonds. Such a process was realized, and mechanistically and computationally investigated. The synthetic potential was demonstrated for the preparation of various oligocyclic frameworks (including natural products) by making use of a variety of different terminating processes [5].
[1] E. Negishi, G. Wang, G. Zhu, Top. Organomet. Chem. 2006, 19, 1-48; [2] M. Leibeling, D. C. Koester, M. Pawliczek, S. C. Schild, D. B. Werz, Nat. Chem. Biol. 2010, 6, 199; [3] J. Wallbaum, R. Neufeld, D. Stalke, D. B. Werz, Angew. Chem. Int. Ed. 2013, 52, 13243; [4] B. Milde, M. Leibeling, M. Pawliczek, J. Grunenberg, P. G. Jones, D. B. Werz, Angew. Chem. Int. Ed. 2015, 54, 1331; [5] a) M. Pawliczek, T. F. Schneider, C. Maaß, D. Stalke, D. B. Werz, Angew. Chem. Int. Ed. 2015, 54, 4119. b) M. Pawliczek, B. Milde, P. G. Jones, D. B. Werz, Chem. Eur. J. 2015, 21, 12303; c) A. Düfert, D. B. Werz, Chem. Eur. J. 2016, 22, 16718; d) B. Milde, M. Pawliczek, P. G. Jones, D. B. Werz, Org. Lett. 2017, 19, 1914.
Professor Cristiano Raminelli
​Title: Benzyne Chemistry: Synthetic Methods and Total Syntheses
Abstract: The benzyne chemistry has found applications in organic chemistry, including total syntheses of natural products and preparations of functional materials. In this context, 2-(trimethylsilyl)aryl trifluoromethanesulfonates can be considered an important alternative for the generation of benzyne and derivatives, enlarging the scope of benzyne chemistry applications in preparative organic chemistry. Accordingly, in our lecture we intend to present useful synthetic methods for the preparation of heterocyclic compounds and concise approaches to the total syntheses of natural products and bioactive compounds, involving the generation of benzyne and derivatives via fluoride-induced reactions under mild conditions.
Professor María Laura Uhrig
​Title: From thiosugars and thiodisaccharides to supramolecular multivalent ligands
Abstract: Thioglycosides and thiodisaccharides represent a synthetic challenge for carbohydrate chemists due to their increasing importance in the Glycobiology field. In these compounds, the anomeric oxygen has been replaced by a sulfur atom, and so, they are considered carbohydrate mimetics with great potential as enzyme inhibitors or new ligands for lectins, given that this replacement does not interfere with recognition events. Moreover, this structural feature makes them more resistant towards enzymatic and acidic hydrolysis. Therefore, the development of new synthetic methods to obtain thiosugars and their use as building blocks for the synthesis of new carbohydrate-derived compounds have been an active research field over the years. In our laboratory, we are interested in developing multivalent systems with high affinity for lectins, constructed from glycomimetics such as thiosugars and thiodisaccharides. Thus, after exploring a range of covalently-constructed multivalent structures, we undertook the study of self-assembled multivalent systems produced from amphiphilic compounds. In all cases, we have incorporated thiosugars such as 1-thiolactose, β-S-N-acetylglucosamine and even thiodisaccharides as recognition elements, which were, at the same time, the polar moiety of the amphihile. Pyrene and resorcinarene systems, as well as long chain diacyl-derived tartaric residues, have been used as hydrophobic residues. Thus, in this presentation I will refer to our latest results on the synthesis and characterization of supramolecular multivalent ligands for lectins. It will include the synthetic results regarding the construction of GlcNAc-thiodisaccharides, and also our experience on a variety of self-assembled and micellar systems, including gels, which have shown high affinity for model lectins.
Professor Braulio Rodríguez-Molina
​Title: Synergic Properties in Organic Crystals: The implication of Motion at the Molecular Level
Abstract: The study and control of the internal motion in crystalline solids is the ultimate goal in the field of molecular rotors and motors. Recently, we have focused on the development of new fluorescent organic materials, trying to regulate the internal dynamics in the solid state. In this presentation, I will discuss the synthesis, structure, inner dynamics, and associated crystal transformations of these rotors, highlighting the cases where the rotary components are able to show ultrafast motion and noticeable macroscopic behavior. The relationship between these properties and their potential applications will be addressed in this talk
Professor Ross Denton
​Title: Organocatalytic Alcohol Activation
Abstract: Nucleophilic substitution reactions are fundamental transformations in organic synthesis because they allow readily available alcohols to be converted into a wide variety of functional groups with predictable inversion of stereochemistry. However, they are inherently wasteful since alcohol activation is necessary and takes place at the expense of a stoichiometric reagent. The lecture will describe the design and development of organocatalytic platforms for catalytic nucleophilic substitution reactions of alcohols and epoxides as well as applications in natural product and active pharmaceutical ingredient synthesis.
Professor László Kürti
​Title: Electrophilic Nitrogen-Transfer Processes
​Abstract: Amines and their derivatives are ubiquitous substances since they make up the overwhelming majority of drug molecules, agrochemicals as well as many compounds that are produced by plants and living organisms (i.e., natural products) [1]. Aromatic amines appear as substructures in more than one third of drug candidates. Not surprisingly, organic chemists spend a considerable amount of their time with the synthesis and late-stage functionalization of amines that serve as key chemical building blocks for the preparation of biologically active compounds, especially in medicinal chemistry. There is an urgent need for the development of novel carbon-nitrogen bond-forming methods and reagents that expand the toolbox of synthetic organic chemists and enable the environmentally friendly construction of complex molecular structures using the fewest number of chemical steps and generating the least amount waste. Given this background, the Kürti group actively pursues catalytic C-N bond-forming strategies and processes (i.e., novel modes of nitrogen-transfer) in which the nitrogen-containing group is introduced directly in an unprotected form (i.e., NH2, NH-alkyl and NH-aryl) [2-6]. Despite the recent substantial research effort focused in this area, progress has been limited. This is in part due to a general lack of development of a wide variety of electrophilic aminating agents and catalysts with finely-tuned electronic and steric properties to provide optimal reactivity with a wide range of substrates. The presentation will highlight our latest results on the currently underexplored field of organocatalytic nitrogen-transfers that allow the direct NH-aziridination of isolated/unactivated C=C bonds with high chemoselectivity. These type of processes are intriguing both from a mechanistic and sustainability point of view.
[1] Kürti, László. “Streamlining Amine Synthesis” – A Perspective. SCIENCE 2015, Vol 348, no 6237, p864-865.
[2] Jat, Jawahar L; Paudyal, Mahesh P.; Gao, Hongyin; Xu, Qing-Long; Yousufuddin, Muhammed.; Devarajan, Deepa; Ess, Daniel H.; Kürti, László and Falck, J.R. “Direct and Stereospecific Synthesis of Unprotected N-H and N-Me Aziridines from Olefins.” Science 2014, Vol 343, no 6166, p 61-65.
[3] Gao, Hongyin; Zhou, Zhe; Kwon, Doo-Hyun; Coombs, James; Jones, Steven; Behnke, Nicole E.; Ess, Daniel H. and Kürti, László. “Rapid heteroatom transfer to arylmetals utilizing multifunctional reagent scaffolds.” Nature Chemistry, 2017.
[4] Zhou, Zhe; Ma, Zhiwei; Behnke, Nicole Erin; Gao, Hongyin and Kürti, László. “Non-Deprotonative Primary and Secondary Amination of (Hetero)Arylmetals.” J. Am. Chem. Soc. 2017, 139, 115-118.
[5] Padmanabha V. Kattamuri, Jun Yin, Surached Siriwongsup, Doo-Hyun Kwon, Daniel H. Ess*, Qun Li, Guigen Li*,, Muhammed Yousufuddin, Paul F. Richardson, Scott C. Sutton and Kürti, László.* “Practical Singly and Doubly Electrophilic Aminating Agents: A New, More Sustainable Platform for Carbon-Nitrogen Bond-Formation.” J. Am. Chem. Soc. 2017, 139, 11184-11196.
[6] Zhou, Zhe; Cheng Qingqing and Kürti, László. “Aza-Rubottom Oxidation: Synthetic Access to Primary a-Aminoketones.” J. Am. Chem. Soc. 2019, 141, 2242-2246.