DOCSLIB.ORG

1 Chapter 19: Carbonyl Compounds III Learning Objectives: 1. Write the Mechanism for Keto-Enol Tautomerization and Explain the C

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
1 Chapter 19: Carbonyl Compounds III Learning Objectives: 1. Write the Mechanism for Keto-Enol Tautomerization and Explain the C Chapter 19: Carbonyl Compounds III Learning Objectives: 1. Write the mechanism for keto-enol tautomerization and explain the consequence of such tautomerizarion in the optical chiral of compound. 2. Remember the approximate p Ka value for the α-hydrogen of a carbonyl group. 3. Provide appropriate bases for the formation of enolate and use such enolate for halogenation and alkylation. 4. Be able to write the general electron-pushing (arrow-pushing) mechanisms of Aldol reaction, Michael reaction, Claisen condensation, and Dieckmann condensation. 5. Be able to write the general electron-pushing (arrow-pushing) mechanisms for decarboxylation of 3-oxocarboxylic acids 6. Be able to employ the above-mentioned reaction for the formation of new carbon-carbon bond Sections: 19.1 Acidity of α-hydrogens* 19.2 Keto-Enol Tautomerism* 19.3 How Enols and Enolate Ions React* 19.4 Halogenation of the α-Carbon of Aldehydes and Ketones* 19.5 Halogenation of the α-Carbon of Carboxylic Acids: The Hell-Volhard-Zelinski (HVZ) Reaction 19.6 α-Halogenated Carbonyl Compounds in Synthesis* 19.7 Using LDA to form an Enolate* 19.8 Alkylation of the α-Carbon of Carbonyl Compounds* 19.9 Alkylation and Acylation of the α-Carbon via an Enamine Intermediate 19.10 Alkylation of the β-Carbon: the Michael Reaction* 19.11 The Aldol Reaction* 19.12 Dehydration of Aldol Addition Products: Formation of α,β -Unsaturated Aldehydes and Ketones* 19.13 The Mixed Aldol Reaction 19.14 The Claisen Condensation* 19.15 The Mixed Claisen Condensation 19.16 Intramolecular Condensation and Addition Reactions* 19.17 Decarboxylation of 3-Oxocarboxylic Acids* 19.18 The Malonic Ester Synthesis: Synthesis of Carboxylic Acids 19.19 The Acetoacetic Ester Synthesis: Synthesis of Methyl Ketones 19.20 Designing a Synthesis VI: Making New Carbon-Carbon Bonds 19.21 Reactions at the α-carbon in Biological Systems # * Sections that will be focused # Sections that will be skipped Recommended additional problems 19.44 – 19.52, 19.54 – 19.64, 19.66 – 19.80 1 Class Note 19.1 Acidity of α-hydrogens A. pKa of α-hydrogen of carbonyl derivatives O O O O R' α R' R' R' NHR OR R H H H H H O O O O O O R' OR R' R R' H H H H B. Resonance effect 2 19.2 Keto-Enol Tautomerism O OH R' R R' R H A. Mechanism in acidic condition B. Mechanism in basic condition 3 19.3 How Enols and Enolate Ions React A. Analysis of enols and enolates 4 19.4 Halogenation of the α-Carbon of Aldehydes and Ketones A. Acid-catalyzed halogenation O O X2 (Cl2, Br2, I2) + H3O CH3 CH2 X 5 B. Base-promoted halogenation O X2 (Cl2, Br2, I2) O (excess) R HO- R CH2 CX2 C. Haloform reaction O X2 (Cl2, Br2, I2) O (excess) HO- CH O 3 + CHX3 6 19.5 Halogenation of the α-Carbon of Carboxylic Acids: The Hell-Volhard-Zelinski (HVZ) Reaction 1) PBr , Br O 3 2 O 2) H2O R R OH OH Br 7 19.6 α-Halogenated Carbonyl Compounds in Synthesis A. Analysis of α-halogenated carbonyl Compounds B. Examples 8 19.7 Using LDA to form an Enolate N lithium diisopropylamide (LDA) 19.8 Alkylation of the α-Carbon of Carbonyl Compounds A. Analysis of the reaction 9 B. Examples (i) 1) LDA, THF OCH3 2) CH3I O (ii) 1) LDA, THF 2) CH3CH2I CN 10 C. Potential problem in alkylation of the α-carbon of carbonyl compounds O 1) LDA, THF CH3 2) CH3I 11 19.9 Alkylation and Acylation of the α-Carbon via an Enamine Intermediate O N catalytic H+ + N H2O H + pyrrolidine enamine A. Examples 1) catalytic H+ O N H 2) CH3Br + 3) H2O, H 12 19.10 Alkylation of the β-Carbon: the Michael Reaction A. Michael reaction O O O - CH3O + CH CH 3 H3C 3 13 B. Examples (i) O O O base (?) + H3CO OCH3 (ii) O O base (?) CN OCH CH + 2 3 H3C 14 C. Stork enamine reaction O N HCl H2O + CH3 15 19.11 The Aldol Reaction OH O O base R R H H R A. Mechanism 16 19.12 Dehydration of Aldol Addition Products: Formation of α,β -Unsaturated Aldehydes and Ketones A. Aldol condensation B. Examples (i) O O - H MeO + H MeOH (ii) O EtO- Na+ EtOH 17 19.13 The Mixed Aldol Reaction A. Potential problem in aldol reaction (i) O EtO- Na+ EtOH (ii) O O MeO- Na+ + MeOH H 18 B. Solution (i) O O - + H MeO Na + H MeOH 19 19.14 The Claisen Condensation and 19.15 The Mixed Claisen Condensation O O O base R R OR' + HOR' OR' R A. Mechanism 20 B. Examples (i) O base (?) OCH2CH3 (ii) O O base (?) OCH3 + OCH2CH3 21 19.16 Intramolecular Condensation and Addition Reactions A. Intramolecular Claisen reaction (Dieckmann condensation) (i) H3CO OCH3 MeO- Na+ MeOH O O (ii) O EtO- Na+ H3CH2CO OCH2CH3 EtOH O 22 B. Intramolecular aldol reaction (i) H3C CH3 MeO- Na+ MeOH O O (ii) O EtO- Na+ H3C CH3 EtOH O 23 (iii) O EtO- Na+ H3C H EtOH O (iv) Robinson annulation O O + base H , heat + + H2O CH3 O 24 19.17 Decarboxylation of 3-Oxocarboxylic Acids A. Easier in acidic condition: mechanism O O O O R OH R O B. Examples of compounds containing 3-oxocarboxylic acid O O O O HO OH OH R R 25 19.18 The Malonic Ester Synthesis: Synthesis of Carboxylic Acids and 19.19 The Acetoacetic Ester Synthesis: Synthesis of Methyl Ketones O O O ? R H3CH2CO OCH2CH3 OH 26 A. Examples: O O O OH OH OH 27 19.20 Designing a Synthesis VI: Making New Carbon-Carbon Bonds O O CO2H synthesis of from H3CO OCH3 28 .
Load more

Recommended publications
  • Stereoselective Reactions of Enolates: Auxiliaries
    1 Stereoselective reactions of enolates: auxiliaries • Chiral auxiliaries are frequently used to allow diastereoselective enolate reactions • Possibly the most extensively studied are the Evan’s oxazolidinones • These are readily prepared from amino acids O O (EtO)2C=O reduction K CO Ph OH 2 3 HN O Ph OH NH2 NH2 Ph (S)-phenylalanine oxazolidinone chiral auxiliary • Enolate formation gives the cis-enolate (remember enolisation of amides) • Two possible conformations exist - but chelation results in one being preferred Li O O O O Me Me N O LDA N O O Me Me Me 1. n-BuLi Me HN O 2. EtCOCl Me Me Me O O Me Li valine LDA derivative O N O O N O Me Me Me Me 123.702 Organic Chemistry 2 Diastereoselective alkylation of Evan’s enolate Li O O O O Me Me N O PhCH2I N O Ph Me Me Me Me I Ph Li O Bn O O O O O H H Me N Me N H Me Me Me Me iso-propyl group blocks bottom face • Clearly (I hope) one face of the enolate is blocked • Chelation results in a rigid structure that provides maximum steric hindrance • The electrophile can only approach from one face 123.702 Organic Chemistry 3 Diastereoselective alkylation of Evan’s enolate Li O O O O Me Me N O PhCH2I N O Ph Me Me Me Me I Ph Li O Bn O O O O O H H Me N Me N H Me Me Me Me iso-propyl group blocks bottom face • Clearly (I hope) one face of the enolate is blocked • Chelation results in a rigid structure that provides maximum steric hindrance • The electrophile can only approach from one face 123.702 Organic Chemistry 4 Diastereoselective functionalisation Li O O O O Br LDA Me Me N O N O H Ph Ph 96% de H O
    [Show full text]
  • Catalytic Direct Asymmetric Michael Reactions
    ORGANIC LETTERS 2001 Catalytic Direct Asymmetric Michael Vol. 3, No. 23 Reactions: Taming Naked Aldehyde 3737-3740 Donors Juan M. Betancort and Carlos F. Barbas III* The Skaggs Institute for Chemical Biology and the Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037 [email protected] Received September 5, 2001 ABSTRACT Direct catalytic enantio- and diastereoselective Michael addition reactions of unmodified aldehydes to nitro olefins using (S)-2-(morpholinomethyl)- pyrrolidine as a catalyst are described. The reactions proceed in good yield (up to 96%) in a highly syn-selective manner (up to 98:2) with enantioselectivities approaching 80%. The resulting γ-formyl nitro compounds are readily converted to chiral, nonracemic 3,4-disubstituted pyrrolidines. The Michael reaction is generally regarded as one of the Typically, carbon nucleophiles that contain an active most efficient carbon-carbon bond forming reactions, and methylene center such as malonic acid esters, â-keto esters, studies concerning this reaction have played an important nitroalkanes, etc. have been studied in the Michael reaction. role in the development of modern synthetic organic Carbonyl compounds, and ketones in particular, have gener- chemistry.1 As the demand for optically active compounds ally only been used as donors following their preactivation has soared in recent years, much progress has been made in by conversion into a more reactive species such as enol or the development of asymmetric variants of this reaction, enamine equivalents.5,6 In these cases, additional synthetic providing for the preparation of Michael adducts with high enantiomeric purity.2 Though remarkable advances have been (3) (a) Chataigner, I.; Gennari, C.; Ongeri, S.; Piarulli, U.; Ceccarelli, S.
    [Show full text]
  • Page 1 of 108 RSC Advances
    RSC Advances This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. This Accepted Manuscript will be replaced by the edited, formatted and paginated article as soon as this is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. www.rsc.org/advances Page 1 of 108 RSC Advances Applications of oxazolidinones as chiral auxiliaries in the asymmetric alkylation reaction applied to total synthesis Majid M. Heravi,* Vahideh Zadsirjan, Behnaz Farajpour Department of Chemistry, School of Science, Alzahra University, Vanak, Tehran, Iran Email: [email protected] Abstract Various chiral oxazolidinones (Evans' oxazolidinones) have been employed as effective chiral auxiliaries in the asymmetric alkylation of different enolates. This strategy has been found promising and successful when used as key step (steps) in the total synthesis of several biologically active natural products. In this report, we try to underscore the applications of Manuscript oxazolidinones as chiral auxiliary in asymmetric alkylation, and particularly in crucial chiral inducing steps in the total synthesis of natural products, showing biological activities.
    [Show full text]
  • Aldol Reactions: E-Enolates and Anti-Selectivity
    Utah State University DigitalCommons@USU All Graduate Plan B and other Reports Graduate Studies 5-2005 Aldol Reactions: E-Enolates and Anti-Selectivity Matthew Grant Anderson Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/gradreports Part of the Organic Chemistry Commons Recommended Citation Anderson, Matthew Grant, "Aldol Reactions: E-Enolates and Anti-Selectivity" (2005). All Graduate Plan B and other Reports. 1312. https://digitalcommons.usu.edu/gradreports/1312 This Report is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Plan B and other Reports by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. ALDOL REACTIONS: E-ENOLATES AND ANTI-SELECTIVITY Prepared By: MATTHEW GRANT ANDERSON A non-thesis paper submitted in partial fulfillment of the requirement for a Plan B Degree of Masters of Science in Organic Chemistry UTAH STATE UNIVERSITY Logan, Utah 2005 Contents Page CONTENTS ...................................................................................... .i LIST OF TABLES, FIGURES AND SCHEMES ....................................... ii,iii ABSTRACT .................................................................................... iv CHAPTER I. ALDOL REACTIONS:E-ENOLATES AND ANTI SELECTIVITY ......... 1 CHAPTER II. SECTION 1. MODELS OF E-ENOLATE FORMATION ...... .... ....... ... 12 SECTION 2. PATERSON ENOLATE PAPER ..... .........................
    [Show full text]
  • Robert Burns Woodward
    The Life and Achievements of Robert Burns Woodward Long Literature Seminar July 13, 2009 Erika A. Crane “The structure known, but not yet accessible by synthesis, is to the chemist what the unclimbed mountain, the uncharted sea, the untilled field, the unreached planet, are to other men. The achievement of the objective in itself cannot but thrill all chemists, who even before they know the details of the journey can apprehend from their own experience the joys and elations, the disappointments and false hopes, the obstacles overcome, the frustrations subdued, which they experienced who traversed a road to the goal. The unique challenge which chemical synthesis provides for the creative imagination and the skilled hand ensures that it will endure as long as men write books, paint pictures, and fashion things which are beautiful, or practical, or both.” “Art and Science in the Synthesis of Organic Compounds: Retrospect and Prospect,” in Pointers and Pathways in Research (Bombay:CIBA of India, 1963). Robert Burns Woodward • Graduated from MIT with his Ph.D. in chemistry at the age of 20 Woodward taught by example and captivated • A tenured professor at Harvard by the age of 29 the young... “Woodward largely taught principles and values. He showed us by • Published 196 papers before his death at age example and precept that if anything is worth 62 doing, it should be done intelligently, intensely • Received 24 honorary degrees and passionately.” • Received 26 medals & awards including the -Daniel Kemp National Medal of Science in 1964, the Nobel Prize in 1965, and he was one of the first recipients of the Arthur C.
    [Show full text]
  • Aldol Condensation
    Chemistry 212 Laboratory Dibenzalacetone via Crossed Aldol Condensation Prelab: Calculate the amounts of all chemicals needed in measurable amounts (i.e. grams or milliliters rather than moles.) Introduction: Aldol condensations are important in organic synthesis, providing a good way to form carbon–carbon bonds. The "aldol" (aldehyde + alcohol) product is a structural unit found in many naturally occurring molecules and pharmaceuticals, and is therefore important. In an Aldol condensation an enolate ion reacts with a carbonyl compound to form a β- hydroxyaldehyde or β-hydroxyketone, followed by dehydration to give a conjugated enone. The general equation is shown in Figure 1. O O O R" B: H R R'" R "R R'" loss of H2O H R' R' Figure 1. The equation for the Aldol Condensation. The reaction involves the nucleophilic addition of an enolate to an aldehyde to form a β-hydroxy carbonyl. The β-hydroxy carbonyl is readily dehydrated under mild conditions. The aldol reaction occurs under both acidic and basic conditions as seen in Figure 2. ENOL pathway (reacts in H O protonated OH form) O O catalytic H+ O O H H R' H2O lost R' R R R' R R H aldol addition product aldol condensation product ENOLATE pathway O O M O M O base O H R' R R' R R enolate H Figure 2. The Aldol reaction and subsequent dehydration under acidic and basic conditions. The reaction we will be doing this week involves the reaction between benzaldehyde and acetone to do a double Aldol Condensation. The overall equation is shown in Figure 3.
    [Show full text]
  • Total Synthesis of Natural Products: a Themed Issue Dedicated to Professor Dr. Dieter Schinzer for His 65Th Birthday”
    molecules Editorial Editorial to the Special Issue “Total Synthesis of Natural Products: A Themed Issue Dedicated to Professor Dr. Dieter Schinzer for His 65th Birthday” Ari M. P. Koskinen Department of Chemistry and Materials Science, Aalto University School of Chemical Engineering, Kemistintie 1, P.O. Box 16100, 02150 Espoo, Finland; ari.koskinen@aalto.fi Received: 4 December 2020; Accepted: 9 December 2020; Published: 10 December 2020 Natural products have intrigued humans throughout history. Plants with physiological activities, fermentation products, extracts with aroma, scent, or other properties have catalyzed the development of physical methods of separation of compounds and eventually the chemical synthesis of compounds. It is no coincidence that the first synthesis of an organic compound was that of a natural product. Since Wöhler’s synthesis of urea (no stereocenters) nearly two centuries ago, the synthesis of natural products has evolved through Komppa’s synthesis of camphor (one independent stereocenter) a century ago to a stage where compounds of enormous complexity can be attained through chemical synthesis (e.g., palytoxin with 64 stereocenters by Kishi in 1994). This development continues undauntedly, and it stimulates the invention of new synthetic reactions, new technological inventions, and new strategic thinking. The synthesis of natural products also stimulates the minds of medicinal chemists to develop ever better pharmaceutical products inspired by nature. Professor Dieter Schinzer had his initial training in organic synthesis with eminent mentors (Professors Manfred Reetz, Clayton Heathcock and Ekkehard Winterfeldt). Despite his wide research interests in organometallic chemistry (especially silicon, tin and manganese), synthetic methodology and medicinal chemistry, Dr. Schinzer is first and foremost a devoted natural product chemist.
    [Show full text]
  • Recoverable Phospha-Michael Additions Catalyzed by a 4-N,N
    molecules Article Recoverable Phospha-Michael Additions Catalyzed by a 4-N,N-Dimethylaminopyridinium Saccharinate Salt or a Fluorous Long-Chained Pyridine: Two Types of Reusable Base Catalysts Eskedar Tessema 1,†, Vijayanath Elakkat 1,† , Chiao-Fan Chiu 2,3,*, Jing-Hung Zheng 1, Ka Long Chan 1, Chia-Rui Shen 4,5, Peng Zhang 6,* and Norman Lu 1,7,* 1 Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan; [email protected] (E.T.); [email protected] (V.E.); [email protected] (J.-H.Z.); [email protected] (K.L.C.) 2 Department of Pediatrics, Linkou Medical Center, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan 3 Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan 4 Department of Medical Biotechnology and Laboratory Sciences, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan; [email protected] 5 Department of Ophthalmology, Linkou Medical Center, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan 6 Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221-0172, USA 7 Development Center for Smart Textile, National Taipei University of Technology, Taipei 106, Taiwan Citation: Tessema, E.; Elakkat, V.; * Correspondence: [email protected] (C.-F.C.); [email protected] (P.Z.); Chiu, C.-F.; Zheng, J.-H.; Chan, K.L.; [email protected] (N.L.) Shen, C.-R.; Zhang, P.; Lu, N. † These authors contributed equally to this work. Recoverable Phospha-Michael Additions Catalyzed by a Abstract: Phospha-Michael addition, which is the addition reaction of a phosphorus-based nucle- 4-N,N-Dimethylaminopyridinium ophile to an acceptor-substituted unsaturated bond, certainly represents one of the most versatile and Saccharinate Salt or a Fluorous powerful tools for the formation of P-C bonds, since many different electrophiles and P nucleophiles Long-Chained Pyridine: Two Types can be combined with each other.
    [Show full text]
  • New Mesoporous Silica-Supported Organocatalysts Based on (2S)-(1,2,4-Triazol-3-Yl)-Proline: Efficient, Reusable, and Heterogeneo
    molecules Article New Mesoporous Silica-Supported Organocatalysts Based on (2S)-(1,2,4-Triazol-3-yl)-Proline: Efficient, Reusable, and Heterogeneous Catalysts for the Asymmetric Aldol Reaction Omar Sánchez-Antonio 1 , Kevin A. Romero-Sedglach 1 , Erika C. Vázquez-Orta 1 and Eusebio Juaristi 1,2,* 1 Departamento de Química, Centro de Investigación y de Estudios Avanzados, Avenida IPN # 2508, 07360 Ciudad de México, Mexico; [email protected] (O.S.-A.); [email protected] (K.A.R.-S.); [email protected] (E.C.V.-O.) 2 El Colegio Nacional, Luis González Obregón # 23, Centro Histórico, 06020 Ciudad de México, Mexico * Correspondence: [email protected] or [email protected] Academic Editor: Derek J. McPhee Received: 16 September 2020; Accepted: 1 October 2020; Published: 3 October 2020 Abstract: Novel organocatalytic systems based on the recently developed (S)-proline derivative (2S)-[5-(benzylthio)-4-phenyl-(1,2,4-triazol)-3-yl]-pyrrolidine supported on mesoporous silica were prepared and their efficiency was assessed in the asymmetric aldol reaction. These materials were fully characterized by FT-IR, MS, XRD, and SEM microscopy, gathering relevant information regarding composition, morphology, and organocatalyst distribution in the doped silica. Careful optimization of the reaction conditions required for their application as catalysts in asymmetric aldol reactions between ketones and aldehydes afforded the anticipated aldol products with excellent yields and moderate diastereo- and enantioselectivities. The recommended experimental protocol is simple, fast, and efficient providing the enantioenriched aldol product, usually without the need of a special work-up or purification protocol. This approach constitutes a remarkable improvement in the field of heterogeneous (S)-proline-based organocatalysis; in particular, the solid-phase silica-bonded catalytic systems described herein allow for a substantial reduction in solvent usage.
    [Show full text]
  • Development of the Interrupted Nazarov Cyclization of Allenyl Vinyl Ketones, with Application to the Total Synthesis of the Cyclooctane Natural Product Roseadione
    Development of the Interrupted Nazarov Cyclization of Allenyl Vinyl Ketones, with Application to the Total Synthesis of the Cyclooctane Natural Product Roseadione by Vanessa M. Marx Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Dalhousie University Halifax, Nova Scotia May 2011 © Copyright by Vanessa M. Marx, 2011 DALHOUSIE UNIVERSITY DEPARTMENT OF CHEMISTRY The undersigned hereby certify that they have read and recommend to the Faculty of Graduate Studies for acceptance a thesis entitled “Development of the Interrupted Nazarov Cyclization of Allenyl Vinyl Ketones, with Application to the Total Synthesis of the Cyclooctane Natural Product Roseadione” by Vanessa M. Marx in partial fulfilment of the requirements for the degree of Doctor of Philosophy. Dated: May 19, 2011 Supervisor: _________________________________ Readers: _________________________________ _________________________________ _________________________________ Departmental Representative: _________________________________ ii DALHOUSIE UNIVERSITY DATE: May 19, 2011 AUTHOR: Vanessa M. Marx TITLE: Development of the Interrupted Nazarov Cyclization of Allenyl Vinyl Ketones, with Application to the Total Synthesis of the Cyclooctane Natural Product Roseadione DEPARTMENT OR SCHOOL: Department of Chemistry DEGREE: PhD CONVOCATION: October YEAR: 2011 Permission is herewith granted to Dalhousie University to circulate and to have copied for non-commercial purposes, at its discretion, the above title upon the request of individuals or institutions. I understand that my thesis will be electronically available to the public. The author reserves other publication rights, and neither the thesis nor extensive extracts from it may be printed or otherwise reproduced without the author’s written permission. The author attests that permission has been obtained for the use of any copyrighted material appearing in the thesis (other than the brief excerpts requiring only proper acknowledgement in scholarly writing), and that all such use is clearly acknowledged.
    [Show full text]
  • Tripeptide-Catalyzed Asymmetric Aldol Reaction Between Α-Ketoesters and Acetone Under Acidic Cocatalyst-Free Conditions
    catalysts Article Tripeptide-Catalyzed Asymmetric Aldol Reaction Between α-ketoesters and Acetone Under Acidic Cocatalyst-Free Conditions Kazumasa Kon 1, Hiromu Takai 2, Yoshihito Kohari 3,* and Miki Murata 1,2,3 1 Graduate School of Manufacturing Engineering, Kitami Institute of Technology, 165 Koen-Cho, Kitami, Hokkaido 090-8507, Japan; [email protected] 2 Graduate School of Materials Science and Engineering, Kitami Institute of Technology, 165 Koen-Cho, Kitami, Hokkaido 090-8507, Japan; [email protected] 3 School of Earth, Energy and Environmental Engineering, Faculty of Engineering, Kitami Institute of Technology, 165 Koen-Cho, Kitami, Hokkaido 090-8507, Japan; [email protected] * Correspondence: [email protected]; Tel.: +81-157-26-9432 Received: 17 April 2019; Accepted: 6 June 2019; Published: 9 June 2019 Abstract: Here, we report the tripeptide-catalyzed asymmetric aldol reaction between α-ketoesters and acetone under acidic cocatalysts-free conditions. H-Pro-Tle-Gly-OH 3g-catalyzed reactions between α-ketoesters and acetone resulted in up to 95% yield and 88% ee. Analysis of the transition state using density functional theory (DFT) calculations revealed that the tert-butyl group in 3g played an important role in enantioselectivity. Keywords: organocatalyst; aldol reaction; peptide catalyst; α-ketoesters 1. Introduction Optically active tertiary alcohols are partial structures present in various natural products and biologically active compounds [1–5]. Various synthetic methods for these compounds have been developed. Asymmetric nucleophile addition to functionalized ketones is one of the most useful synthetic methods, because highly functionalized optically active tertiary alcohols, which can undergo various transformations, can be obtained.
    [Show full text]
  • Reaction of Glucose Catalyzed by Framework and Extraframework Tin Sites in Zeolite Beta
    Reaction of Glucose Catalyzed by Framework and Extraframework Tin Sites in Zeolite Beta Thesis by Ricardo Bermejo-Deval In Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2014 (Defended 12 May 2014) ii 2014 Ricardo Bermejo-Deval All Rights Reserved iii ACKNOWLEDGEMENTS The past years at Caltech have been one of the most challenging periods of my life, learning to be a better person and being part of the world of science. I feel privileged to have interacted with such talented and inspiring colleagues and scientists, as well as those I have disagreed with. The variety of people I have encountered and the experiences I have gathered have helped me to gain scholarship, wisdom, confidence and critical thinking, as much as to become an open-minded person to any opinion or people. First and foremost, I am very grateful to my advisor and mentor, Professor Mark E. Davis, for his financial, scientific and personal support. I appreciate his patience, flexibility, advice and scientific discussions, helping me to grow and mature scientifically. I would like to thank the thesis committee Professors Richard Flagan, Jay Labinger and Theodor Agapie, for their discussions and kindness. I appreciate everyone in the Davis group for helping me in the lab throughout these years. Special thanks to Yasho for helping me get started in the lab, to Bingjun and Raj for scientific advice, and to Marat for helpful talks. I am also very thankful to Sonjong Hwang for SS NMR, David Vandervelde for NMR and Mona Shahgholi for mass spectrometry.
    [Show full text]