Regioselectivity and Diastereoselectivity of Three
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Stereochemistry CHAPTER3
28 Stereochemistry CHAPTER3 Stereochemistry Stereochemistry : It involves the study of the relative spatial arrangement of atoms within the molecules. Dynamic stereochemistry: Dynamic stereochemistry is the study of the effect of stereochemistry on the rate of a chemical reaction. First Stereochemist – Louis Pasteur (1849): Significance of stereochemistry: One of the most infamous demonstration of the significance of stere- ochemistry was the Thalidomide disaster. Thalidomide is a drug was first prepared in 1957 in Germany, prescribed for treating morning Sickness in pregnant women. It was discovered that one optical isomer i.e. R- Isomer of the drug was safe whereas the S-isomer had teratogenic effect, causing serious genetic damage to early embryonic growth and development. O O H O O H N N 1 2 N 3 O N O H H 4 O R-isomer O S-isomer Drug for morning sickness in pregnant women. Teratogenic effect [Remark: In human body, Thalidomide undergoes racemization: even if only one of the two stereoisomers is ingested, the other one is produced.] Now we have another example - Propanolol. H H N N O O H OH OH H R-Propanolol (contraceptive) S-Propanolol (antihypertensive) Stereochemistry 29 SOME TERMINOLOGY Optical activity: The term optical activity derived from the interaction of chiral materials with polarized light. Scalemic: Any non-racemic chiral substance is called Scalemic. • A chiral substance is enantio pure or homochiral when only one of two possible enantiomer is present. • A chiral substance is enantio enriched or heterochiral when an excess of one enantiomer is present but not the exclusion of the other. -
Organic Chemistry Frontiers
ORGANIC CHEMISTRY FRONTIERS View Article Online REVIEW View Journal | View Issue Progress in the synthesis of perylene bisimide dyes Cite this: Org. Chem. Front., 2019, 6, Agnieszka Nowak-Król and Frank Würthner * 1272 With their versatile absorption, fluorescence, n-type semiconducting and (photo-)stability properties, per- ylene bisimides have evolved as the most investigated compounds among polycyclic aromatic hydro- carbons during the last decade. In this review we collect the results from about 200 original publications, reporting a plethora of new perylene bisimide derivatives whose properties widely enrich the possibility for the application of these dyes beyond traditional fields. While some applications are highlighted, different from other recent reviews, our focus here is on the advances in the synthetic methodologies Received 17th December 2018, that have afforded new bay functionalizations, recently addressed functionalizations at the ortho-positions Accepted 17th February 2019 to the carbonyl groups, and annulation of carbo- and heterocyclic units. An impressive number of DOI: 10.1039/c8qo01368c perylene bisimide oligomers are highlighted as well which are connected by single bonds or spiro linkage rsc.li/frontiers-organic or in a fused manner, leading to arrays with fascinating optical and electronic properties. Creative Commons Attribution 3.0 Unported Licence. Introduction are the leading examples of the class of tetrapyrrole dyes, PBIs are the most important compounds of the family of polycyclic About a hundred years after their discovery, perylene-3,4:9,10- aromatic hydrocarbons. This outstanding role of PBIs has bis(dicarboximide)s, commonly abbreviated as PDIs or PBIs, evolved not only due to their properties, but also due to the have emerged as one of the most important classes of func- incredible development of the synthetic chemistry of this class tional dyes. -
Copyrighted Material
Index Abbreviations receptor sites 202, 211 weak 122 amino acids, Table 500–1 muscarinic 413 weak, pH calculation 147–8 nucleic acids 551 nicotinic 413 Acid–base nucleotides, Table 551 as quaternary ammonium salt 202 catalysis, enzymes 516 peptides and proteins 504 Acetylcholinesterase equilibria 121 phosphates and diphosphates 277 enzyme mechanism 519–21 interactions, predicting 155–7 structural, Table 14 hydrolysis of acetylcholine 279 Acidic reagents, Table 157 ACE (angiotensin-converting enzyme) inhibitors 279 Acidity enzyme action 532 Acetyl-CoA carboxylase, in fatty acid acidity constant 122 inhibitors 532 biosynthesis 595 bond energy effects 125 Acetal Acetyl-CoA (acetyl coenzyme A) definition 121 in etoposide 233 as acylating agent 262 electronegativity effects 125 formation 229 carboxylation to malonyl-CoA 595, hybridization effects 128 polysaccharides as polyacetals 232 609 inductive effects 125–7 as protecting group 230 Claisen reaction 381 influence of electronic and structural Acetal and ketal enolate anions 373 features 125–34 cyclic, as protecting groups 481 in Krebs cycle 585 and leaving groups, Table 189 groups in sucrose 231 from β-oxidation of fatty acids 388 pKa values 122–5 Acetaldehyde, basicity 139 as thioester 262, 373 resonance / delocalization effects 129–34 Acetamide, basicity 139 Acetylene, bonding molecular orbitals 31 Acidity (compounds) Acetaminophen, see paracetamol Acetylenes, acidity 128 acetone 130 Acetoacetyl-CoA, biosynthesis from N-Acetylgalactosamine, in blood group acetonitrile 365 acetyl-CoA 392 -
New Chiral Auxiliaries for the [3+2]-Cycloaddition of Nonstabilised Azomethine Ylides
New Chiral Auxiliaries For The [3+2]-Cycloaddition Of Nonstabilised Azomethine Ylides Allan Rostrup Forup Jensen A thesis submitted in partial fulfilment of the degree of Doctor of Philosophy Christopher Ingold Laboratories University College London London 20 Gordon Street WC1H OAJ ProQuest Number: 10610918 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10610918 Published by ProQuest LLC(2017). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 /\cjmowieugemenis First and foremost I wish to thank my supervisor, Professor K. J. Hale, for the constant support, encouragement and guidance he has provided throughout the duration of this project. I also wish to take this opportunity to thank my sponsor, Rhone- Poulenc-Rorer, without whom this project would not have been possible. I also wish to thank past and present members of the Hale group for their friendship and encouragement. In particular, Dr. J. Cai was an invaluable help and inspiration. For their friendship and enormous support through good and bad times, Rukpong Tupprasoot, Neha Jogiya, Andrew Calabrese, Dr. Gurpreet Bhatia, Marc Hummersone, Rafaqat Hussain, also deserve to be mentioned. -
Organic Stereoisomerism
Organic : Stereoisomerism Stereoisomerism Introduction: When two compounds have same structure(hence same name) but still they are not identical and some of their properties are different then it means they are stereoisomers. They are not superimposable with each other. They differ in the spatial relationship between their atoms or groups. See this example. CH3 CH3 CH3 H CC CC H H H CH3 cis(Z)-but-2-ene trans(E)-but-2-ene Both are but-2-ene, but they are not identical. Their melting points and boiling points are different. They evolve different heat energy when hydrogenated. So what is the difference between them ? Is it structure- wise ? The answer is NO, as their structures are same i.e but-2-ene. They differ with respect the relationship between some atoms or groups in space. In cis-but-2-ene, the –CH3 groups are on the same side of the double bond and so also the H atoms. However, in trans-but-2-ene, the –CH3 groups lie on opposite sides of the double bond and so also the H atoms. For that reason, the two are not superimposable with each other. If you carry the model of cis-but-2-ene and try to overlap with trans-but-2-ene for the purpose of matching of groups and atoms, what do you find ? Are the two superimposable ? When one –CH3 group matches, the other not. When one –H atom matches, the other not. Thus the structures are non-superimposble. This kind of stereoisomerism is called Geometrical Isomerism(now-a-days called E-Z isomersm), because the geometrical relationsip between groups are different. -
The Use of Spirocyclic Scaffolds in Drug Discovery ⇑ Yajun Zheng , Colin M
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Bioorganic & Medicinal Chemistry Letters 24 (2014) 3673–3682 Contents lists available at ScienceDirect Bioorganic & Medicinal Chemistry Letters journal homepage: www.elsevier.com/locate/bmcl BMCL Digest The use of spirocyclic scaffolds in drug discovery ⇑ Yajun Zheng , Colin M. Tice, Suresh B. Singh Vitae Pharmaceuticals Inc., 502 West Office Center Drive, Fort Washington, PA 19034, United States article info abstract Article history: Owing to their inherent three-dimensionality and structural novelty, spiro scaffolds have been increas- Received 15 April 2014 ingly utilized in drug discovery. In this brief review, we highlight selected examples from the primary Revised 17 June 2014 medicinal chemistry literature during the last three years to demonstrate the versatility of spiro scaffolds. Accepted 27 June 2014 With recent progress in synthetic methods providing access to spiro building blocks, spiro scaffolds are Available online 5 July 2014 likely to be used more frequently in drug discovery. Ó 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND Keywords: license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Spirocyclic Scaffold Drug discovery One widely used strategy in drug design is to rigidify the ligand present in a number of bioactive natural products such as mito- conformation by introducing a ring.1 The resulting cyclic analog mycins, it is generally difficult to construct such aziridines from will suffer a reduced conformational entropy penalty upon binding unfunctionalized olefins. A recent report of a facile synthetic route to a protein target. -
The Arene–Alkene Photocycloaddition
The arene–alkene photocycloaddition Ursula Streit and Christian G. Bochet* Review Open Access Address: Beilstein J. Org. Chem. 2011, 7, 525–542. Department of Chemistry, University of Fribourg, Chemin du Musée 9, doi:10.3762/bjoc.7.61 CH-1700 Fribourg, Switzerland Received: 07 January 2011 Email: Accepted: 23 March 2011 Ursula Streit - [email protected]; Christian G. Bochet* - Published: 28 April 2011 [email protected] This article is part of the Thematic Series "Photocycloadditions and * Corresponding author photorearrangements". Keywords: Guest Editor: A. G. Griesbeck benzene derivatives; cycloadditions; Diels–Alder; photochemistry © 2011 Streit and Bochet; licensee Beilstein-Institut. License and terms: see end of document. Abstract In the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para photocycloaddition. This short review aims to demonstrate the synthetic power of these photocycloadditions. Introduction Photocycloadditions occur in a variety of modes [1]. The best In the presence of an alkene, three different modes of photo- known representatives are undoubtedly the [2 + 2] photocyclo- cycloaddition with benzene derivatives can occur, viz. the addition, forming either cyclobutanes or four-membered hetero- [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para cycles (as in the Paternò–Büchi reaction), whilst excited-state photocycloaddition (Scheme 2). The descriptors ortho, meta [4 + 4] cycloadditions can also occur to afford cyclooctadiene and para only indicate the connectivity to the aromatic ring, and compounds. On the other hand, the well-known thermal [4 + 2] do not have any implication with regard to the reaction mecha- cycloaddition (Diels–Alder reaction) is only very rarely nism. -
Catenanes and Quasi&Lsqb;1&Rsqb;Rotaxanes Via A
UvA-DARE (Digital Academic Repository) Synthesis of spiro quasi[1]catenanes and quasi[1]rotaxanes via a templated backfolding strategy Steemers, L.; Wanner, M.J.; Lutz, M.; Hiemstra, H.; van Maarseveen, J.H. DOI 10.1038/ncomms15392 Publication date 2017 Document Version Final published version Published in Nature Communications License CC BY Link to publication Citation for published version (APA): Steemers, L., Wanner, M. J., Lutz, M., Hiemstra, H., & van Maarseveen, J. H. (2017). Synthesis of spiro quasi[1]catenanes and quasi[1]rotaxanes via a templated backfolding strategy. Nature Communications, 8, [15392]. https://doi.org/10.1038/ncomms15392 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:29 Sep 2021 ARTICLE Received 3 Mar 2017 | Accepted 27 Mar 2017 | Published 25 May 2017 DOI: 10.1038/ncomms15392 OPEN Synthesis of spiro quasi[1]catenanes and quasi[1]rotaxanes via a templated backfolding strategy Luuk Steemers1, Martin J. -
1,3-Dipolar Cycloaddition of Azomethine Ylides Generated from Aziridines in Supercritical Carbon Dioxide Paulo J
Tetrahedron Letters 47 (2006) 5475–5479 1,3-Dipolar cycloaddition of azomethine ylides generated from aziridines in supercritical carbon dioxide Paulo J. S. Gomes, Cla´udio M. Nunes, Alberto A. C. C. Pais, Teresa M. V. D. Pinho e Melo* and Luis G. Arnaut Department of Chemistry, Coimbra University, 3004-535 Coimbra, Portugal Received 8 March 2006; revised 26 May 2006; accepted 30 May 2006 Abstract—The 1,3-dipolar cycloaddition of azomethine ylides with DMAD in supercritical carbon dioxide is reported. The photo- lysis reaction conditions were optimized with a suitable adjustment of pressure, temperature, irradiation time and co-solvent concen- tration leading to a more efficient reaction than in neat acetonitrile. Similar results were observed using thermal reaction conditions. Supercritical carbon dioxide with a minute co-solvent addition is shown to be a very efficient medium for promoting this type of cycloadditions. Ó 2006 Elsevier Ltd. All rights reserved. Over the last decade, supercritical fluids (SCF) received ology for the synthesis of nitrogen-heterocyclic significant attention as a new class of environmentally compounds. We chose the 1,3-dipolar cycloaddition friendly solvents for organic synthesis. Supercritical flu- of azomethine ylides generated from aziridines as the ids have properties intermediate between the gas and the model reaction. Aziridines (1) undergo electrocyclic ring liquid phases that can be tuned simply by changing the opening in a disrotatory manner upon irradiation and pressure and temperature. In particular, changes of pres- conrotatory ring opening upon thermolysis, giving sure close to the critical point enable drastic changes in azomethine ylides (2), which participate in 1,3-dipolar density and viscosity. -
Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis Christopher K
Review pubs.acs.org/CR Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis Christopher K. Prier, Danica A. Rankic, and David W. C. MacMillan* Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, United States References 5360 1. INTRODUCTION CONTENTS A fundamental aim in the field of catalysis is the development 1. Introduction 5322 of new modes of small molecule activation. One approach 2+ toward the catalytic activation of organic molecules that has 2. Photochemistry of Ru(bpy)3 5323 3. Net Reductive Reactions 5324 received much attention recently is visible light photoredox 3.1. Reduction of Electron-Poor Olefins 5324 catalysis. In a general sense, this approach relies on the ability of 3.2. Reductive Dehalogenation 5326 metal complexes and organic dyes to engage in single-electron- 3.3. Reductive Cleavage of Sulfonium and transfer (SET) processes with organic substrates upon Sulfonyl Groups 5328 photoexcitation with visible light. 3.4. Nitrogen Functional Group Reductions 5329 Many of the most commonly employed visible light 3.5. Radical Cyclizations 5330 photocatalysts are polypyridyl complexes of ruthenium and iridium, and are typified by the complex tris(2,2′-bipyridine) 3.6. Reductive Epoxide and Aziridine Opening 5331 2+ 3.7. Reduction-Labile Protecting Groups 5331 ruthenium(II), or Ru(bpy)3 (Figure 1). These complexes 4. Net Oxidative Reactions 5332 4.1. Functional Group Oxidations 5332 4.2. Oxidative Removal of the PMB Group 5334 4.3. Oxidative Biaryl Coupling 5335 4.4. Oxidative Generation of Iminium Ions 5335 4.5. Azomethine Ylide [3 + 2] Cycloadditions 5338 4.6. -
A** 2' 0 11 Cnev\
CONJUGATE ADDITIONS AND REDUCTIVE TRANSFORMATIONS OF FULVENES AND 6-VINYLFULVENES A thesis submitted to the faculty of San Francisco State University A** In partial fulfillment of 3 (c the requirements for 2 ' 0 11 the Degree c n e v \ Master of Science In Chemistry: Organic Synthesis by Teresa de Jesus Ortega San Francisco, California August 2019 Copyright by Teresa de Jesus Ortega 2019 CERTIFICATION OF APPROVAL I certify that I have read Conjugate additions and reductive transformations of fulvenes and 6-vinylfulvenes by Teresa de Jesus Ortega, and that in my opinion this work meets the criteria for approving a thesis submitted in partial fulfillment of the requirement for the degree Master of Science in Chemistry: Organic synthesis at San Francisco State University. Ihsan Erden, Ph.D Professor in Chemistry Taro Amagata, Ph.D Professor in Chemistry Weiming Wu, Ph.D Professor in Chemistry CONJUGATE ADDITIONS AND REDUCTIVE TRANSFORMATIONS OF FULVENES AND 6-VINYLFULVENES Teresa de Jesus Ortega San Francisco, California 2019 Fulvenes are a group of cross-conjugated compounds that have been of interest due to their diverse chemical and physical properties. Since the discovery of fulvenes by Thiele in the 1900s, and improved synthetic methods, fulvene chemistry has been explored and applications in organometallic chemistry and natural product synthesis have been unveiled. Herein, we disclose our results on the reactions of fulvenes and 6-vinylfulvenes with carbon nucleophiles and reducing agents. For this study, the carbon nucleophiles selected includes the carbon acids nitromethane and ethyl nitroacetate, furthermore, the reducing agent consists of UAIH4. Moreover, selective diazene reduction of fulvenes has been explored in the hopes of gaining a convenient access to 1,2-dihydrofulvenes. -
PERSONAL ACCOUNT Binap and Phosphoramidites As Privileged
PERSONAL ACCOUNT Carmen Nájera,*[a] and José M. Sansano*[b] Binap and phosphoramidites as Dedication ((optional)) privileged chiral ligands for the metal-catalyzed enantioselective 1,3-dipolar cycloaddition of azomethine ylides and dipolarophiles ((Insert Picture for Frontispiece here [18.0×18.0 cm])) [a] Title(s), Initial(s), Surname(s) of Author(s) including Corresponding Author(s) Department Institution Address 1 E-mail: [b] Title(s), Initial(s), Surname(s) of Author(s) Department Institution Address 2 Supporting information for this article is given via a link at the end of the document.((Please delete this text if not appropriate)) 1 PERSONAL ACCOUNT Abstract: Binap and phosphoramidites are privileged chiral starting from enolizable substrates I and electron-deficient ligands which have been tested in the coinage metal-catalyzed alkenes III promoted by coinage metals and the named chiral 1,3-dipolar cycloadditions of metalloazomethine ylides and ligands on the basis of the dipolarophile employed (Scheme 1). electrophilic alkenes. Silver(I), copper(II) and gold(I) salts have Rigid chiral metallodipoles II control of the final absolute been evaluated in all these reactions. Maleimides, acrylates, configuration of the up to four stereogenic centers of fumarates, 1,2-bis(phenylsulfonyl)ethylene and enones reacted polysubstituted proline derivatives IV. with imino esters giving the corresponding endo-prolinates such as HCV inhibitors in high diastereo- and enantioselectivity. In the case of nitroalkenes exo-4-nitroprolinates were obtained. Azlactones reacted with maleimides and acrylates to give pyrrolines only in the presence of binap-gold(I) complexes. The observed enantioselectivity and the mechanism of these 1,3-DC was studied by means of DFT calculations.