============================================================== 제 목 : Construction of Quaternary Stereocenters via Pd-Catalyzed Asymmetric Decarboxylative Cycloaddition 연 사 : Prof. Yong Jian Zhang 일 시 : 2017년 11월 23일(목) 오전 10시 30분 장 소 : 화학관 2층 서병인강의실 (330226호실) ============================================================== Construction of Quaternary Stereocenters via Pd-Catalyzed Asymmetric Decarboxylative Cycloaddition Yong Jian Zhang School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China email@example.com The development of efficient methods for the construction of quaternary stereogenic centers is an important objective in modern organic synthesis. In this presentation, I will present our recent research results for the construction of quaternary stereogenic centers via palladium-catalyzed asymmetric decarboxylative cycloaddition of vinylethylene carbonates (VECs) with unsaturated electrophiles. By using chiral palladium complex as catalysts under mild conditions, the transformations that enable rapid access valuable functional heterocycles bearing quaternary stereocenters in high yields and high levels of stereoselectivities.
============================================================== 제 목 : C−H Activation Using Organophosphorus Compounds 연 사 : 이필호 교수님(강원대학교 화학과) 일 시 : 2017년 11월 16일(목) 오후 4시 30분 장 소 : 화학관 2층 서병인강의실 (330226호실) ============================================================== C−H Activation Using Organophosphorus Compounds Phil Ho Lee Department of Chemistry, Kangwon National University C−H bond functionalizations catalyzed by transition metals are interesting since these procedures permit for a more clear-cut synthetic strategy to products devoid of demanding prefunctionalization of starting materials, thus avoiding byproducts in step-economical manner. In order to have a broad synthetic strategy in a C−H functionalization, the desired C−H bond in the starting material should be selectively activated over all the C‒H bonds existing in the substrate. In particular, since there is a trivial difference in the reactivity between the C−H bonds in aromatic compounds, a selective C‒H bond functionalization is very crucial. Recently, a series of examples of C−C and C−heteroatom bond formation have been described by introducing directing groups. As a consequcnce, a number of coordinating directing groups have been employed for atom- and step-economical C−H bond functionalization. Among those, imines, amides and heterocyclic compounds bearing nitrogen are most frequently utilized as directing groups. In addition, C−H functionalization using hydroxyl and carboxyl as directing groups through weak coordination has been studied to a great extent. However, there is still a need to develop useful functional groups for direct ortho-selective C−H bond cleavage, which will provide a significant effect in synthetic applications. Encouraged by a number of transition metal-catalyzed cyclizations using a carboxylic acid group, we imagined that C−H bond functionalization with phosphonic acid monoesters would perform as a desirable platform for the preparation of phosphaisocoumarins, which may be phosphorus heterocycles exhibiting effective biological activity. Moreover, to date, phosphaisocoumarin scaffolds have been synthesized through intramolecular cyclization. Although alkynylarylphosphates or their monoesters have been used in the cyclization, as far as we know, Rh-catalyzed cyclization using alkynes and arylphosphonic acid monoesters has not been utilized for the synthesis of phosphaisocoumarins. Furthermore, to the best of our knowledge, methods using phosphorus compound as a directing group is few. Inspired by recent our interests in organophosphorus compounds, we decided to examine C−H bond functionalization with phosphonic acid monoester. Rh-catalyzed cyclization of phosphinic acids and phosphonic monoesters with alkynes has been developed. The oxidative annulations proceeds with complete conversion of phosphinic acid derivatives and allowed the atom-economic preparation of useful phosphaisocoumarins with high yield and selectivity. The reaction is tolerant of extensive substitution on the phosphinic acid, phosphonic monoester and alkyne, including halides, ketone, and hydroxyl groups as substituents. Furthermore, we found that alkenylphosphonic monoesters proceed to give a wide range of phosphorus 2-pyrones through oxidative annulations with alkynes. Mechanistic studies revealed that C−H bond metalation was the rate-limiting step. An efficient and cost-effective Ru-catalyzed oxidative cyclization of phosphonic acid monoesters or phosphinic acids with alkynes has been developed for the synthesis of a wide range of phosphaisocoumarins in good to excellent yields under aerobic conditions. A multitude of arylphosphonic acid monoesters and arylphosphinic acids having electron-donating and -withdrawing groups were oxidatively cyclized. Various diarylacetylenes, dialkylacetylenes, and alkylarylacetylenes effectively underwent Ru-catalyzed oxidative cyclization. A substrate possessing benzoic acid as well as a phenylphosphonic monoester moiety was smoothly cyclized with hex-3-yne to afford a compound having both isocoumarin and phosphaisocoumarin moieties. Alkenylphosphonic monoester afforded phosphorus 2-pyrone through oxidative cyclization with alkyne. Competition experiments between diaryl- and dialkylalkynes and between diarylacetylenes having 4-methoxy and 4-chloro groups gave results which showed that the present oxidative cyclizations were not affected by the electronic effects of alkynes. Mechanistic studies revealed C−H bond metalation to be the rate-limiting step. References 1. Chan, L. Y.; Kim, S.; Ryu, T.; Lee, P. H. Chem. Commun. 2013, 49, 4682. 2. Chary, B. C.; Kim, S.; Park, Y.; Kim, J.; Lee, P. H. Org. Lett. 2013, 15, 2692. 3. Seo, J.; Park, Y.; Jeon, I.; Ryu, T.; Park, S.; Lee, P. H. Org. Lett. 2013, 15, 3358. 4. Ryu, T.; Kim, J.; Park, Y.; Kim, S.; Lee, P. H. Org. Lett. 2013, 15, 3986. 5. Park, S.; Seo, B.; Shin, S.; Son, J.-Y.; Lee, P. H. Chem. Commun. 2013,49, 8671. 6. Mo, J.; Lim, S.; Park, S.; Ryu, T.; Kim, S.; Lee, P. H. RSC Adv. 2013, 3, 18296. 7. Park, Y.; Seo, J.; Park, S.; Yoo, E. J.; Lee, P. H. Chem. Eur. J. 2013,19, 16461. 8. Kim, C.-E.; Ryu, T.; Kim, S.; Lee, K.; Lee, C.-H.; Lee, P. H. Adv. Synth. Catal. 2013, 355, 2873. 9. Kang, D.; Cho, J.; Lee, P. H. Chem. Commun.2013, 49, 10501. 10. Park, Y.; Jeon, I.; Shin, S.; Min, J.; Lee, P. H. J.Org. Chem. 2013, 78, 10209. 11. Eom, D.; Jeong, Y.; Kim, Y. R.; Lee, E.; Choi, W.; Lee, P. H. Org. Lett. 2013,15, 5210. 12. Kim, J.; Kang, D.; Yoo, E. J.; Lee, P. H. Eur. J. Org. Chem. 2013, 7902. 13. S. Shin, D. Kang, W. H. Jeon, P. H. Lee, Beilstein J. Org. Chem. 2014, 10, 1220 (invited). 14. Shin, S.; Jeong, Y.; Jeon, W. H.; Lee, P. H. Org. Lett. 2014, 16, 2930. 15. Kim, Y. R.; Cho, S.; Lee, P. H. Org. Lett.2014, 16, 3098. 16. Kim, C.-E.; Son, J.- Y.; Shin, S.; Seo, B.; Lee, P. H. Org. Lett. 2015, 17, 908. 17. Jeon, W. H.; Son, J.-Y.; Kim, S.-E.; Lee, P. H.Adv. Synth. Catal. 2015, 357, 811. 18. Son, J.-Y.; Kim, H.; Jeon, W. H.; Baek, Y.; Seo, B.; Um, K.; Lee, K.; Lee, P. H. Adv. Synth. Catal. 2017, 359, 3194.
============================================================== 제 목 : Ab initio molecular dynamics on nanoscale 연 사 : Prof. Rustam Z. Khaliullin(McGill University) 일 시 : 2017년 11월 9일(목) 오후 4시 30분 장 소 : 화학관 2층 서병인강의실 (330226호실) ============================================================== Ab initio molecular dynamics on nanoscale Rustam Z. Khaliullin Department of Chemistry, McGill University, Quebec, Canada Despite remarkable recent progress in linear-scaling density function theory, the computational cost of exist-ing methods remains too high for routine ab initio molecular dynamics (AIMD) simulations. We developeda linear-scaling AIMD method with an extremely low computational overhead by assuming that electronsin materials are strictly localized within prede ned radii. High eciency of the method is achieved withoutsacri cing its accuracy with a combination of two techniques: (1) on-the-y construction of accurate localizedorbitals without lengthy optimization and (2) the stochastic integrator that is ne-tuned to retain stabledynamics even with imperfect forces. A remarkable feature of the implemented method is that it remainsecient for challenging condensed phase systems even if large accurate basis sets are used. We demonstratedthat, for systems well-represented by localized electrons (e.g. molecular systems, ionic salts), the new AIMDmethod enables simulations on previously inaccessible time and length scales. Applications of the methodto more challenging systems of strongly interacting atoms (e.g. covalent crystals) will also be discussed.1
===================================================================================== 제 목 : Investigation of Innovative Synthetic Approach for Successful Implementation of Fragment-Based Design 연 사 : 홍승우 교수님(KAIST) 일 시 : 2017년 6월 7일(수) 오전 11시 장 소 : 화학관 1층 첨단강의실 (330118호실) ===================================================================================== Investigation of Innovative Synthetic Approach for Successful Implementation of Fragment-Based Design Sungwoo Hong Center for Catalytic Hydrocarbon Functionalizations & Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, Korea e-mail: firstname.lastname@example.org Solutions to problems that are posed by organic, medicinal, biological and material science, demand synthetic innovation with efficient synthetic routes. Our current research is focused on studying breakthrough knowledge in catalytic synthetic methods and molecular design that have high impact on broader scientific fields. The state-of-the-art of approach can be seen using systematic experimental and theoretical methods from three steps: (1) development of innovative synthetic methods that allow rapid access to molecular complexity and structural diversity of privileged fragments, (2) fragment-based drug design (FBDD) and de novo design methods connecting privileged building blocks, (3) development of potent and selective inhibitors based on understanding the mechanisms at the molecular level. The selective C–H bond functionalization has become the favored reaction methods in practical synthetic processes. The new catalytic synthetic methods allow us to perform the unprecedented disconnection of target molecules, affording innovative and imaginative synthetic strategies of so-called “privileged scaffolds”. The power and efficiency of direct C–H functionalization could be further enhanced by combining such catalytic transformations into a one-pot process, which is highly desirable by providing a powerful platform for constructing complicated key motifs from simple starting materials. Subsequent medicinal chemistry studies involving a modular approach and privileged fragments assembly, will provide bases for the development of pharmaceutical agents via structure-based design. The new catalytic synthetic methods will function as competent tools directly utilized in cross coupling reactions capable of connecting privileged building blocks, providing opportunities for the successful implementation of fragment-based drug design (FBDD) and eventually streamline drug discovery research.
============================================================== 제 목 : Evolution of Form in Metal-Organic Frameworks 연 사 : 최원영 교수님(UNIST) 일 시 : 2017년 6월 1일(목) 오후 4시 30분 장 소 : 화학관 2층 서병인 강의실 (330226호실) ============================================================== Evolution of Form in Metal-Organic Frameworks Wonyoung Choe Department of Chemistry Ulsan National Institute of Science and Technology Ulsan, 44919 Self-assembly has proven to be a widely successful synthetic strategy for functional materials, especially for Metal-Organic Materials (MOMs), an emerging class of porous materials consisting of Metal-Organic Frameworks (MOFs) and Metal-Organic Polyhedra (MOPs). However, there are areas in MOM synthesis in which such self-assembly has not been fully utilized, such as controlling the interior of MOM crystals. Here, we demonstrate sequential self-assembly strategy for synthesizing various forms of MOM crystals, including double-shell hollow MOMs, based on single-crystal to single-crystal transformation from MOP to MOF. Moreover, this synthetic strategy also yields other forms, such as solid, core-shell, double and triple matryoshka, and single-shell hollow MOMs, thereby exhibiting form evolution in MOMs. We anticipate that this synthetic approach might open up a new direction for the development of diverse forms in MOMs, with highly advanced areas such as sequential drug delivery/release and heterogeneous cascade catalysis targeted in the foreseeable future.
====================================== 제 목 : Multiselective Diels–Alder Reaction Induced by Chiral Supramolecular Lewis Acid Catalysts 연 사 : Prof. Kazuaki Ishihara(Nagoya University) 일 시 : 2017년 5월 18일(목) 오후 4시 15분 장 소 : 화학관 1층 첨단강의실(330110호) -------------------------------------- Multiselective Diels–Alder Reaction Induced by Chiral Supramolecular Lewis Acid Catalysts Kazuaki Ishihara Nagoya University, Japan The control of multiple selectivities is still a challenging subject in modern organic chemistry. In this regard, the Diels–Alder (DA) reaction is a significant tool for the total synthesis of complex organic molecules. When used in the DA reaction, conventional chiral catalysts can discriminate the prochiral enantio-face (i.e., re/si-face) of a dienophile regardless of the diene (two-dimensional discrimination). However, they cannot control the diastereo- (i.e., endo/exo-), regio-, site-, or substrate-selectivity, since this would require the three-dimensional discrimination of isomeric transition-state structures. In general, huge enzymes in vivo can realize such multi-selectivity by using a chiral cavity, which provides a three-dimensional space that includes an active site. The cavities of enzymes are conformationally flexible to catch substrates and release products (induced fit function). To overcome the limited selectivity due to the small cavity and conformational rigidity of conventional chiral Lewis acid catalysts, supramolecular catalysts, which are prepared in situfrom small components by coordinating bonds, have been considered. Indeed, there are a few examples of the use of supramolecular O-shaped catalysts that induce anomalous site-selectivity in DA reactions. However, their catalytic activities are not adequate due to their conformational rigidity. In contrast, Prof. Ishihara et al.envisioned that chiral supramolecular U-shaped catalysts, which are more conformationally flexible than O-shaped catalysts, could induce high catalytic activity with multi-selectivity. In this lecture, Prof. Ishihara presents that an asymmetric DA reaction of propargyl aldehyde with cyclopentadiene can be controlled so as to provide high enantio-, endo/exo-, regio-, and substrate-selectivities by using chiral supramolecular U-shaped catalysts.
====================================== 제 목 : 현대화학에서 계산양자화학의 역할: 어제와 오늘 연 사 : 이윤섭 교수님(한국과학기술원 화학과) 일 시 : 2017년 4월 27일(목) 오후 4시 15분 장 소 : 화학관 1층 첨단강의실(330110호) -------------------------------------- 현대화학에서 계산양자화학의 역할: 어제와 오늘 이윤섭 한국과학기술원 화학과 계산양자화학의 역사는 전산기의 발달과 궤를 같이하여 최근에 눈부시게 발전하고 있고 당분간은 급속한 확대추이가 지속되리라 예상된다. 그간 계산양자화학의 방법론 발달에서 중요한 사항과 그에 따른 응용예의 확산을 살펴보고자 하는데, 객관적 중요성을 충분히 반영한 역사나 개요보다는 연사의 경험과 관련된 주제의 간단한 설명으로 양자화학에서 상대론 효과를 취급하는 방법과 상대론 효과에 영향을 받은 분자 구조와 특성의 의미 있는 변화를 주로 소개한다. 현대화학이란 어휘는 학문의 특정분야로 인식이 이루어지고 있지는 않으나 현대물리학이 양자역학과 상대성원리를 근간으로 하고 있음을 생각하면, 상대론적 양자화학을 현대화학의 주요주제로 간주할 수 있겠다. 상대론 효과가 현재 수행되는 다수의 양자화학 계산에 일부나마 포함되어 있음을 고려할 때 전자구조에서 나타나는 상대론 효과의 정성적 이해는 미래를 위한 방법론 개발과 현명한 양자화학 계산 응용에 필요하다. 일례로 동전용 금속들에서 금이 은보다 동에 가깝게 보임은 주요원인이 에너지 준위에 영향을 주는 상대론적 효과 때문이다.
============================================================== 제 목 : Physical-Organic Approaches to Studying Protein Chemistry 연 사 : Prof. Kyungtae Kang(Department of Applied Chemistry, Kyung Hee University) 일 시 : 2017년 4월 13일(목) 오후 4시 30분 장 소 : 화학관 2층 서병인 강의실 (330226호실) ============================================================== Physical-Organic Approaches to Studying Protein Chemistry Kyungtae Kang Department of Applied Chemistry, Kyung Hee University, 1732 Dyeogyoung-daero, Giheung-gu, Youngin, Gyeonggi 17104, Republic of Korea Biomolecular recognition is governed as much by rearrangements of the water that hydrates the interacting molecules as it is governed by their direct interactions. A detailed understanding of the mechanisms by which these rearrangements contribute to the thermodynamics of recognition processes is, thus, essential for better understanding—and predicting—the energetics of important biomolecular recognitions. In this respect, the hydrophobic effect—the tendency of nonpolar surfaces to associate in aqueous solution—is one of the major driving forces of many biomolecular recognition events. The hydrophobic effect arises from free energetically favorable rearrangements of water, whose thermodynamic consequences are fairly well understood for flat, nonpolar entities in aqueous solution (where the intermolecular association of such entities gives rise to the entropically favorable, enthalpically unfavorable release of ordered waters from their surfaces), but incompletely understood—and difficult to predict—for interactions between ligands and the morphologically complex and chemically heterogeneous binding pockets of proteins. In this talk, I will introduce our efforts to examine the role of water filling the binding pocket of human carbonic anhydrase II (HCAII, EC 4.2.11) in its bindings with structurally varied sulfonamide ligands, by combining isothermal titration calorimetry, X-ray crystallography, site-directed mutagenesis, and molecular dynamics simulations. By this set of methods, we showed that (i) the hydrophobic surface area of a ligand does not improve DGºb, unless that increased non-polar area is buried in the binding process, and values of DHºb and -TDSºb depend on the structure (or morphology) of a ligand; (ii) reorganizing networks of water inside the binding pocket by mutating amino acids thereof brings about huge and compensating changes in values of DHºband -TDSºb. References 1. D. Chandler, Nature437, 640 (2005). 2. P. W. Snyder, M. R. Lockett, D. T. Moustakas, G. M. Whitesides, Eur. Phys. J.-Spec. Top. 223, 853 (2013).
===================================================================================== 제 목 : Chiral Tetrahydrothiophene Ligands in Asymmetric Catalysis 연 사 : Prof. Rong-Jie Chein(Institute of Chemistry, Academia Sinica) 일 시 : 2017년 4월 4일(화) 오후 4시 30분 장 소 : 화학관 1층 강의실 (330118호실) ===================================================================================== Chiral Tetrahydrothiophene Ligands in AsymmetricCatalysisRong-Jie CheinInstitute of Chemistry, Academia Sinica, Nankang, Taipei 11529, TaiwanE-mail: email@example.com Chiral sulfur ligands are becoming a versatile tool in organic chemistry due to theblossomed development achieved in the past years. This presentation describes anexpeditious and efficient preparation of enantiopure (thiolan-2-yl)diarylmethanols andthe applications of their derivatives to catalytic and asymmetric Corey-Chaykovskyepoxidation,1 the imino Corey-Chaykovsky aziridination,2,3 as well as the firstoxathiaborenium catalyzed asymmetric Diels-Alder reaction.4,5 Figure 1. Synthesis and applications of chiral THT ligands Reference1. Wu, H.-Y.; Chang, C.-W.; Chein, R.-J. J. Org. Chem. 2013, 78, 5788-5793.2. Huang, M.-T.; H.-Y. Wu; Chein, R.-J. Chem. Commun. 2014, 50, 1101-1103.3. Wang, S.-H.; Chein, R.-J. Tetrahedron, 2016, 72, 2607-2615..4. Kumar, S. N.; Yu, I. F.; Chein, R.-J. Org. Lett. 2017, 19, 22-25. (Highlighted byC&EN 2017, 95(1), 9).5. Tsai, M.-L.; Chein, R.-J. to be submitted.Rong-Jie Chein (陳榮傑), National Chiao Tung University (Ph.D., 2005), HarvardUniversity (Postdoctoral Fellow, E. J. Corey Lab, Jan. 2007 - June 2009). AssistantResearch Fellow of Academia Sinica (July 2009 - May 2015). Associate ResearchFellow (May 2015 - ). Research fields: (1) Development of new synthetic strategiesand methods. (2) Total synthesis and the study of the chemistry and biology of naturalproducts and designed molecules.
============================================================== 제 목 : Soft Matter at Rubbing Interfaces: Lessons from Nature to Design Water-friendly Tribosystems 연 사 : 이승환 교수님(Technical University of Denmark) 일 시 : 2017년 3월 30일(목) 오후 4시 30분 장 소 : 화학관 2층 서병인강의실 (330226호실) ============================================================== Soft Matter at Rubbing Interfaces: Lessons from Nature to Design Water-friendly Tribosystems Seunghwan Lee Department of Mechanical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark Life-long maintenance of biotribosystems, such as synovial joints, ocular tracts, and oral cavity, is remarkable and even puzzling considering that the base stock for the lubrication is water. For most man-made engineering systems, water is generally excluded as lubricant due to its poor capabilities to withstand external loads on its own. Nature solves this problem by incorporating pressure-responsive, “smart coatings”, such as mucus gel layers on the surface, and thus facilitate the entrainment and retainment of water (lubricant) at the rubbing interfaces. Mucins, a family of high-molecular-weight glycoproteins and a main macromolecular constituent of mucus gels, are interesting also because they show unique slipperiness at the interface composed of synthetic materials too. This, in turn, has inspired the development of mucin-like, brush-forming synthetic polymers, which can be applied in the lubrication of engineering materials with water. Biophysical properties of both mucinous glycoproteins and their mimics, brush-forming polymers, are very sensitive to environmental changes, and this feature can be exploited to optimize their properties for particular applications. Studies on soft matter at the rubbing interfaces firstly help understand the biological mechanisms of lubrication and provide useful hints for biomimetic lubrication engineering. Furthermore, various fundamental properties of soft matter on surface can be revealed only by being exposed to interfacial shear stresses. This talk will provide an overview on recent researches on the conformation, surface adsorption, and biotriobological properties of mucins/mucus gels with varying origin, purity, and environment as well as synthetic brush-like polymer chains, including poly(ethylene oxide)(PEO)-based copolymers, carbohydrate-based copolymers, and polyeletrolyte-based copolymers.