====================================== 제 목 : Tailor-made Synthesis of Multilayered Trimetallocyclophanes via Transannula p-p Interactions 연 사 : 정옥상 교수님(부산대학교 화학과) 일 시 : 2018년 4월 5일(목) 오후 4시 15분 장 소 : 화학관 1층 첨단강의실(330118호) -------------------------------------- Tailor-made Synthesis of Multilayered Trimetallocyclophanes via Transannula p-pInteractions Ok-Sang Jung* Department of Chemistry, Pusan National University, Pusan 609-735, Korea Abstract Synthesis and operation of a nano-demension 24 × 24 × 15 Å3 “left and right ball-joint-type host-guest system” via one π∙∙∙π interaction and three NH∙∙∙O=C hydrogen-bonds along with the combined helicity are described. The system consists of unprecedented conglomerate aggregates of two distinct helical metallacyclophanes, chiral isomer (P)-[Pd3X6(L1)2]@(M)- [Pd3X6(L1)(L2)] and its enantiomer (M)-[Pd3X6(L1)2]@(P)- [Pd3X6(L1)(L2)]are described. Successive reactions afford desirable four-layered metallacyclophanes via tailor-made procedure. Synthesis and operation of a nano-demension size multilayered metallacyclophane system via one π∙∙∙π interaction along with the combined helicity are described. A synthetic strategy of generation of new molecular species utilizing a provision of nature has been reported: nano-dimensional (23(2) × 21(1) × 16(1) Å3) hetero four-layered trimetalla- cyclophanes via the proof-of-concept experiments that utilize a suitable combination of π∙∙∙π interactions between the central aromatic rings, tailor-made short/long spacer tridentate donors, and the combined helicity are constructed. The unprecedented four-layered metallacyclophane system’s behavior offers a landmark in the development of new molecular system.
============================================================== 제 목 : Transition-Metal-Catalyzed Coupling ReactionsDecarboxylative Coupling & High Throughput Screening Methods 연 사 : 이선우 교수님(전남대학교) 일 시 : 2018년 3월 15일(목) 오후 4시 30분 장 소 : 화학관 2층 세미나실(330226호실) ============================================================== Transition-Metal-Catalyzed Coupling Reactions Decarboxylative Coupling & High Throughput Screening Methods Sunwoo Lee* Department of Chemistry, Chonnam National University, Gwangju 61186 Republic of Korea Transition-metal-catalyzed decarboxylative coupling of alkynoic acids have been studied by our lab for a decade. Since our first report that palladium-catalyzed reactions of aryl halides and propiolic acids afforded the symmetrical and unsymmetrical diaryl alkynes in good yields, a variety of related methodology have been reported by many research groups including us. The development of simple and convenient method for the preparation of aryl alkynoic acids made it easy accessible tool for the introduction of alkynyl group in organic synthesis. Although the decarboxylative coupling of alkynoic acids and Sonogahsira type coupling of terminal alkyne showed similar reactivity in most cases, the unique reactivity of alkynoic acid has been found in the multicomponent reactions including metal-free reactions. Especailly, arylpropiolic acids readily prepared from the coupling reaction of aryl halides and propiolic acid without column chromatography procedure. In this presentation, we would like to discuss some of our recent research progress towards the decarboxylative coupling reactions of alkynoic acids. The development of efficient reaction conditions often requires many rounds of screening. This can be especially true in the case of metal-catalysed couplings, such as the always-popular palladium-catalyzed cross couplings, where it may be necessary to investigate the metal source, ligand, solvent, reaction temperature and bases as well as other additives. Because of the demand for the fast analysis of reaction leads to synthetic methodology development, we developed colorimetric analysis methods using gold nanoparticles, chemosensor and paper based colorimetric iodide sensor (PBCIS). In this seminar, the recent developed decarboxylative coupling reactions and high throughput screening protocol will be presented.
============================================================== 제 목 : Photosynthesis of Value-added Chemicals from Carbon Dioxide and Water Using Oxide Semiconductors 연 사 : 박현웅 교수님(경북대학교) 일 시 : 2017년 12월 14일(목) 오후 4시 30분 장 소 : 화학관 1층 대강의실 (330102호실) ============================================================== Photosynthesis of Value-added Chemicals from Carbon Dioxide and Water Using Oxide Semiconductors Hyunwoong ParkSchool of Energy Engineering, Kyungpook National University, Daegu 41566, Korea E-mail: firstname.lastname@example.org As the costs of carbon-footprinted fuels change continuously and atmospheric carbon dioxideconcentration increases, solar fuels are receiving growing attention as alternative cleanenergy carriers. These fuels include molecular hydrogen and hydrogen peroxide producedfrom water, and hydrocarbons converted from carbon dioxide. For high efficiency solar fuelproduction, not only light absorbers (oxide semiconductors, Si, inorganic complexes, etc)should absorb most sunlight, but also charge separation and interfacial charge transfers needto occur efficiently. Recently, there is renewed interest in the photocatalytic andphotoelectrochemical conversion of CO2 into value-added chemicals using varioussemiconductor particles and electrodes. Common CO2 reduction products are C1 chemicals(CO, HCOOH, CH3OH, and CH4) in aqueous media, while the production of C2-C4hydrocarbons (e.g., C2H6 and C3H8) has also been reported. A number of solar-activematerials have been reported, but they still suffer from low selectivity, poor energy efficiency,and instability, while failing to drive simultaneous water oxidation. This talk presents ourrecent studies on the solar CO2 conversion to value-added chemicals while using water as anelectron donor in various photo-systems.
====================================== 제 목 : Multiple routes of light signaling to the roots - Photochemical approaches - 연 사 : 박충모 교수님(서울대학교) 일 시 : 2017년 11월 30일(목) 오후 4시 15분 장 소 : 화학관 1층 대강의실(330102호) -------------------------------------- Multiple routes of light signaling to the roots - Photochemical approaches - Chung-Mo Park Department of Chemistry, Seoul National University Tel: 02-880-6640, e-mail: email@example.com Living organisms sustain their growth and performance through intricate communications with surrounding environments under changing climates. Accumulating evidence support that the living organisms-environment communication occurs via a wide variety of chemicals, which are often termed chemical language. Light is one of the most important communication media that affect plant growth and development by influencing virtually all aspects of plant growth and developmental processes throughout plant life. A group of photoreceptors perceives a wide range of light wavelengths, such as ultra-violet (UV), blue (B), red (R), and far-red (FR), to monitor the plant’s surrounding environment. The roles of photoreceptors and associated signaling mechanisms have been extensively investigated mostly in the photomorphogenic processes of aerial plant parts. Notably, recent studies strongly support that light also influences the underground root system. However, how the aboveground light influences the root system has not been explored. Here, we show that light is efficiently piped through the stems to the roots, where photoactivated phytochrome B (phyB) triggers photomorphogenic responses, such as root growth and gravitropism. These findings demonstrate that the underground roots directly sense stem-piped light to monitor the aboveground environment during environmental adaptation. Our data would also provide molecular insights into plant intellectual behaviors and, in particular, clues as to a long-sought hypothesis ‘Do plant roots harbor brain or brain-like tissues?’ proposed by Charles Darwin.
============================================================== 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 firstname.lastname@example.org 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: email@example.com 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.