DOCSLIB.ORG

C2-Symmetric Chiral Bis(Oxazoline) Ligands in Asymmetric Catalysis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
C2-Symmetric Chiral Bis(Oxazoline) Ligands in Asymmetric Catalysis Chem. Rev. 2006, 106, 3561−3651 3561 C2-Symmetric Chiral Bis(Oxazoline) Ligands in Asymmetric Catalysis Giovanni Desimoni,*,† Giuseppe Faita,† and Karl Anker Jørgensen*,‡ Department of Organic Chemistry, University of Pavia, Viale Taramelli 10, 27100 Pavia, Italy, and Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark Received January 25, 2006 Contents contribution to the art of organic synthesis has become of leading importance.1,2 In the field of chiral Lewis acid 1. Introduction 3561 catalysis, the catalyst, in general, consists of a cation 2. Syntheses of Box Ligands 3562 coordinated/bound to an optically active ligand to give a 3. Structures of Box−Metal Complexes 3566 chiral complex with at least one vacant Lewis acid site 4. Two Commercial Ligands as Box Prototypes: 3570 suitable for coordination and activation of the reagent. To Reactions Using 4-Phenyl- and induce a good level of enantioselection, the coordinated 4-tert-Butyl-Box-Based Catalysts reagent should be suitably oriented to favor a selective attack 4.1a. Intermolecular Cyclopropanation Reactions 3570 to one specific face. One approach to an easier and less costly 4.1b. Intramolecular Cyclopropanation Reactions 3573 route to reduce half the variables required for good face 4.2. Aziridination Reactions 3574 selectivity is the use of a C2-symmetric chiral ligand. 4.3. Aldol and Aldol-like Reactions 3577 C2-symmetric bis(oxazolines) (box’s) are one of the most 4.4. Michael and Mukaiyama−Michael Reactions 3586 popular classes of chiral ligands satisfying all these require- 4.5. Allylic Substitution Reactions 3591 ments, which have received a great deal of attention as 4.6. Radical Reactions 3593 ligands in coordination chemistry3 and in asymmetric 4a 4.7. Diels−Alder Reactions 3596 catalysis. These ligands have two oxazoline rings separated 4.8. Hetero Diels−Alder Reactions 3600 by a spacer, and C2-symmetric bis(oxazolines) having a single carbon atom with two identical substituentssdifferent 4.9. 1,3-Dipolar Cycloaddition Reactions 3605 from hydrogen as the spacersare the topic of this review. 4.10. Ene and Hetero Ene Reactions 3608 The content will try to cover all aspects of these box ligands, 4.11. Other Pericyclic Reactions 3609 except those immobilized on heterogeneous media since a 4.12. Miscellaneous Reactions 3613 recent review deals with this concept.5 5. Other Box Ligands: Effects of Substituents on 3615 In 1991 two back-to-back communications appeared in the the Catalytic Behavior Journal of the American Chemical Society, one by Evans et 5.1. 4-Aryl-Substituted Box’s 3615 al. dealing with asymmetric cyclopropanation of alkenes6 and 5.2. 4-Aryl-5-Substituted Box’s 3616 one by Corey et al. about enantioselective Diels-Alder 5.3. 4-Alkyl-Substituted Box’s 3620 reactions,7 applying chiral Cu(I)- and Fe(III)-box com- 5.4. 4-Alkyl-5-Substituted Box’s 3625 plexes as catalysts, respectively. 5.5. 4-Aryl- and 4-Alkyl-5,5-Disubstituted Box’s 3625 These two communications induced a small revolution in 5.6. Heteroatoms in 4- or 5-Substituents 3626 the field of asymmetric catalysis. The box ligands quickly 5.7. Substituents Other Than Methyls on the 3628 became widely adopted bidentate ligands for their easy and Methylene Bridge flexible synthesis and for the excellent enantioselectivity Downloaded via UNIV OSNABRUECK on September 7, 2019 at 19:09:45 (UTC). 5.8. Effect of Strained Cyclic Substituents on the 3631 induced first in two very useful reactions, and later in a Box Geometry large variety of other reactions. The communications also 6. Complexes of Phenyl- and tert-Butyl-Box’s with 3639 anticipated the usual protocol of research in box chem- See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. Different Inorganic Salts and Their Behaviors as istry: (a) synthesis of the ligand following a sequence Efficient Asymmetric Catalysts that, for a long time, would become a standard (reaction 7. Relation between the Different Reagents 3642 of dialkylmalonyl dichloride with an optically active 1,2- Coordinated to Phenyl- and tert-Butyl-Box Metal amino alcohol, conversion of the bis-hydroxyamide to the Catalysts and the Stereochemical Outcome corresponding bis-chloroamide, and ring closure under 8. Conclusion 3647 basic conditions); (b) preparation of the chiral catalyst by 9. Aknowledgments 3647 reaction of the box ligand with an inorganic salt (CuOTf 10. References 3647 and FeCl2/I2); (c) testing of the chiral Lewis acid complex as a catalyst for asymmetric induction in the reaction; (d) proposal of a reacting intermediate in which the reagent is 1. Introduction coordinated to the chiral Lewis acid-box complex to Asymmetric catalysis with chiral metal complexes has rationalize the stereochemical outcome of the catalytic received considerable attention in recent years, and its process. This historic approach to asymmetric catalysis with chiral * Corresponding authors. E-mail: [email protected]; [email protected]. - † University of Pavia. Lewis acid box complexes will be followed in this review ‡ Aarhus University. that will cover the literature from 1991 to the spring of 2005 10.1021/cr0505324 CCC: $59.00 © 2006 American Chemical Society Published on Web 08/02/2006 3562 Chemical Reviews, 2006, Vol. 106, No. 9 Desimoni et al. Giovanni Desimoni was born in 1936. He received his laurea degree from Karl Anker Jørgensen was born in 1955 in Aarhus, Denmark, and he the University of Pavia. After a research and teaching period at the same received his Ph.D. from Aarhus University in 1984. He was a post-doctoral university and one year with Alan Katritzky at UEA, in 1975 he joined the researcher with Professor Roald Hoffmann, Cornell University. In 1985 Science Faculty at the University of Pavia as a full professor. He was Karl Anker Jørgensen became an assistant professor at Aarhus University Dean of the Faculty and Director of the Department of Organic Chemistry. and became a professor in 1992. His research interests are the His recent research interests concern the development of new catalysts development, understanding, and application of asymmetric catalysts with for enantioselective reactions, especially those derived from optically active a focus on chiral Lewis-acid-catalyzed reactions and organocatalysis. heterocycles used as chiral ligands, and the understanding of their mechanisms in inducing selectivity. Figure 1. Number of papers dealing with C2-symmetric chiral box ligands appearing in the literature. Giuseppe Faita was born in 1962 and received his degree in Chemistry in 1986 at the Univeristy of Pavia. In 1990 he obtained his Ph.D. at the same university under the supervision of G. Desimoni and he became a (B1) or with 1 equiv of alkyl dihalide to construct a ring on researcher in the Desimoni group in the Department of Organic Chemistry. the spacer (B2); In 2000 he became an associate professor of Organic Chemistry. His re- (C) the manipulations of either the chiral groups on the search interests concern the optimization of asymmetric catalysts involving oxazoline rings (C1) or the groups on the spacer (C2), the Box and Pybox as chiral ligands and solid-phase organic syntheses. former being used to introduce heteroatoms sometimes useful as internal auxiliary ligands to increase the standard bico- (ca. 400 papers) whose frequency strongly increased in the ordination of the box ligand and the latter in general being last years as shown in Figure 1. used to introduce functions suitable for grafting the box ligand to a solid surface. 2. Syntheses of Box Ligands Method A has several variants, some being simple mod- The syntheses of box ligands can be roughly classified ifications of the original protocol, and some, much more into three different categories, the last two being modifica- original, may have important drawbacks on the chirality of tions of preformed box: the ligand. For these reasons method A will be discussed in (A) the construction of the oxazolidine rings starting from detail. a symmetrically disubstituted malonic acid derivative (the Scheme 1 reports the variants of the reaction starting from bis-substituted spacer) and 2 equiv of optically active disubstituted malonyl dichloride that reacts with 2 equiv of â-amino alcohol (the chiral messenger), the method followed â-amino alcohol to give the corresponding bis-amide. This by Evans and Corey in their pioneering work; is the key intermediate of the classic approach to box, with (B) the substitution of two hydrogen atoms with two several variants. Method A1 was that first used by Corey et 7 identical groups on the spacer of a preformed box (followed al. and consists of the transformation with SOCl2 into the when the spacer requires substituents other than methyl), a bis-dichloride that is then cyclized to the box under different method that is based on the acidity of the methylene protons. basic conditions. The hydroxy groups of the bis-amide can This method consists of the formation of a dianion with 2 also be transformed with mesyl or tosyl chloride into good equiv of NaH or BuLi (rarely with Et3N) and in the leaving groups suitable to give box under basic conditions nucleophilic substitution either with 2 equiv of alkyl halide (method A2). Sometimes the bis-amide can be (more or less Bis(Oxazoline) Ligands in Asymmetric Catalysis Chemical Reviews, 2006, Vol. 106, No. 9 3563 Scheme 1 Scheme 2 refluxing solvent with CaH2 or molecular sieves (MS) 4 Å, SO2Cl2 or ZnCl2 in refluxing ClCH2CH2Cl, or more sophis- ticated conditions with diethylaminosulfur trifluoride or the poly(ethylene glycol) (PEG)-linked version of methyl N- (triethylammonium-sulfonyl)carbamate (Burgess reagent). A variant of method A can be used when the targeted 4-substituted box is also 5,5-disubstituted.
Load more

Recommended publications
  • Elucidating How Wood Adhesives Bond to Wood Cell Walls Using High-Resolution Solution-State NMR Spectroscopy
    Elucidating How Wood Adhesives Bond to Wood Cell Walls using High-Resolution Solution-State NMR Spectroscopy Daniel J. Yelle U.S. Forest Service, Forest Products Laboratory Madison, WI, 53726, USA [email protected] Introduction Lignin, 25-30% of wood, is a phenolic polymer made Some extensively used wood adhesives, such as up of branched phenylpropanoid units that are capable of pMDI (polymeric methylene diphenyl diisocyanate) and reacting with other phenols during adhesive bonding. PF (phenol formaldehyde) have shown excellent adhesion Model compound studies have shown that under alkaline properties with wood. However, distinguishing whether conditions and ≥100 °C, β-aryl ether linkages release for- the strength is due to physical bonds (i.e., van der Waals, maldehyde to give vinyl ether linkages (Figure 2a) [10]. London, or hydrogen bond forces) or covalent bonds be- Phenylcourmaran linkages release formaldehyde in a simi- tween the adherend and the adhesive is not fully under- lar fashion to give stilbene linkages (Figure 2b) [10]. 13C stood. Previous studies, where pMDI model compounds NMR spectroscopy showed that most of this released for- were reacted with wood, showed that carbamate (urethane) maldehyde ends up as the methylene bridge between the 5- formation with wood polymers is only possible when: 1. positions on guaiacyl units (Figure 2c) [11]. the number of moles of isocyanate is significantly higher a. HO H O than the moles of water molecules in the wood, 2. high γ γ HO β β α O 4 α β O 4 α O 4 temperatures are used, and 3. the isocyanate-based com- OCH3 OCH - OH 3 OCH3 O + CH pound is of low molecular weight [1].
    [Show full text]
  • Synthesis, Structure and Attempted Polymerization of a Diepoxide Macrocycle Paul Yarincik Sacred Heart University
    Sacred Heart University DigitalCommons@SHU Chemistry & Physics Faculty Publications Chemistry and Physics 10-2012 Synthesis, Structure and Attempted Polymerization of a Diepoxide Macrocycle Paul Yarincik Sacred Heart University Jeffrey H. Glans Sacred Heart University, [email protected] Follow this and additional works at: http://digitalcommons.sacredheart.edu/chem_fac Part of the Polymer Chemistry Commons Recommended Citation Yarincik, Paul and Glans, Jeffrey H., "Synthesis, Structure and Attempted Polymerization of a Diepoxide Macrocycle" (2012). Chemistry & Physics Faculty Publications. 1. http://digitalcommons.sacredheart.edu/chem_fac/1 This Article is brought to you for free and open access by the Chemistry and Physics at DigitalCommons@SHU. It has been accepted for inclusion in Chemistry & Physics Faculty Publications by an authorized administrator of DigitalCommons@SHU. For more information, please contact [email protected]. Letters in Organic Chemistry, 2012, 9, 545-548 545 Synthesis, Structure and Attempted Polymerization of a Diepoxide Macrocycle Paul Yarincik and Jeffrey H. Glans* Department of Chemistry, Sacred Heart University, Fairfield, CT 06825, USA Received October 19, 2011: Revised December 31, 2011: Accepted January 04, 2012 Abstract: A novel diepoxide containing paracyclophane was synthesized by peracid oxidation of a known paracyclo- phane diene. The resulting diepoxide was characterized. It was investigated as a potential monomer for a cyclophane con- taining polyether by cationic ring opening polymerization. None of the standard catalyst systems for such a polymeriza- tion were successful in producing polymer. Keywords: Cationic polymerization, cyclophane, diepoxide, macrocycle. R INTRODUCTION R O O O+ Cationic polymerization of olefins is one of the major R+ routes to high molecular weight polymers [1]. The mecha- O O+ O nism involves nucleophilic attack of the alkene functional group on the electron poor initiator (initiation) or the grow- ing cationic chain end (propagation).
    [Show full text]
  • Or· 8-Annoquriioltlmb WITH. NIT~~~OI,4
    BIBIUD.~; TliE REACTION 8-AnNOQuriiOLtlmB WITH. NIT~~~OI,4 •' >'•' • or·I,' ",i. by Hugh Bu:rknla·p.·,:Ilona.hoe B.s.• ,. Rookhurst College, 194.3 M.A.,, Univ&rESi.ty of ICansas, · 1947 . Submitted to the Department of ·chemistry and the Faculty. of. the . G:raduate School or the University of Kansas in partial fulfillment ot the ?'equirements for the de• gree of Doctor ot Philosophy. Advisory Committee · May, 19.$0 AOKNOWLEOOMENT The author wishes to ex.press his thanks and appreciation to Dr. J. H. Burokhalter,, who suggested this problem, and Dr. a. A. Vanderwerf for ·their helpful suggestions and guidance during the course of this work. H.B.D. TABLE OF OONTEN'TS Chapter Page I • THE PROBLE?i Olr MALARIA. A. Introduction • • • • • . • • 1 B. The types of malaria. • • • • • • •• 2 O. The biology of malarial infection • • 3 D. The prophylaxis and treatment of malaria: •. ;•' •. • • •. • . ;.. • • : •••• ·• • • ., 6 II. ·Atfl'IMALARIAL ·:DRUGS. :· • · ,, A. Olassific at ion and. screening of antimalarial drugs • • . ,, . .. ' . • • • • 12 B. Historical • • • • • • • • • • • • • 1~ c. Quinine • .. • • • .. • • • • • • • • • 16 D. Synthetic substitutes • • • • • • • • 19 l. Plasmochin • • • • • .. • • • • • 19 2 •. Quinaorine • • • • • .. • • • • • 21 3. Ohloroquine • • • • • • • • • •• 21 q.. Pentaquine •• • • • • • • • • • 23 s. Paludrine • • • • • • • • • • • • 2q. E. Me(lhanism ot action of antimalarial drugs • • • • • • • •• • • • • • • • 2$ 1. The metabolite-antimetaboli te relationship • • • • • • • •• • 2.$ 2. The quinoid•Quinonimine theory • 26 3. Conclusions • • • • • • • • • •• 28 · -Ohapter III.· THE ANTIMALARIAL PROGRAM 1941-1945 . .A. The overall program • • • • • • • • • 30 .a. :._ Tb(j ·4•aminoquinolinea • • • • • • • • .32 · <h ·. The 8-aminoqu.inolines • : • . • • • • • • 34. IV. • DISCUSSION Of THE PROBLEM ) • • • • • .• • • • .38 ·V. · DISCUSSION OF· RESULTS. · - . A.;, Unsymmetrical hybrids related to '. propanediemine * • • • • •. • • • • • 46 B. ··Symmetrical: hybrida related to prc,pan~di8J1iinet ~d methanediamine • • S2 .
    [Show full text]
  • Converting Disulfide Bridges in Native Peptides to Stable Methylene Thioacetals
    Chemical Science View Article Online EDGE ARTICLE View Journal | View Issue Converting disulfide bridges in native peptides to stable methylene thioacetals† Cite this: Chem. Sci.,2016,7, 7007 C. M. B. K. Kourra and N. Cramer* Disulfide bridges play a crucial role in defining and rigidifying the three-dimensional structure of peptides. However, disulfides are inherently unstable in reducing environments. Consequently, the development of strategies aiming to circumvent these deficiencies – ideally with little structural disturbance – are highly sought after. Herein, we report a simple protocol converting the disulfide bond of peptides into highly stable methylene thioacetal. The transformation occurs under mild, biocompatible conditions, enabling the conversion of unprotected native peptides into analogues with enhanced stability. The developed Received 23rd May 2016 protocol is applicable to a range of peptides and selective in the presence of a multitude of potentially Accepted 24th July 2016 reactive functional groups. The thioacetal modification annihilates the reductive lability and increases the DOI: 10.1039/c6sc02285e serum, pH and temperature stability of the important peptide hormone oxytocin. Moreover, it is shown www.rsc.org/chemicalscience that the biological activities for oxytocin are retained. Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Introduction disulde bond engineering emerged as an important strategy to improve the metabolic stability of disulde-containing peptides, Peptides have recently been enjoying a renewed interest in whilst maintaining their biological activity. For instance, their application as therapeutic agents.1 They provide a large replacements of the disulde group with a lactam,10 thioether,11 a chemical space with a diverse array of molecular frameworks selenium12 or dicarba13 analogues have been reported.5 Many of for the development of novel therapeutics for a plethora of these methods require signicant modication of the synthetic biomedical applications.
    [Show full text]
  • Structure and Conformation of Bilirubin
    364 C. C. KUENZLE, M. H. WEIBEL AND R. R. PELLONI Kuenzle, C. C. (1970b) Biochem. J. 119, 411-435 Kuenzle, C. C., Weibel, M. H., Pelloni, R. R. & Kuenzle, C. C. (1973) in Metabolic Conjugation andMeta- Hemmerich, P. (1973), Biochem. J. 133, 364-368 bolic Hydrolysis (Fishman, W. H., ed.), vol. 3, Academic von Dobeneck, H. & Brunner, E. (1965) Hoppe-Seyler's Press, New York, in the press Z. Physiol. Chem. 341, 157-166 APPENDIX Structure and Conformation of Bilirubin OPPOSING VIEWS THAT INVOKE TAUTOMERIC EQUILIBRIA, HYDROGEN BONDING AND A BETAINE MAY BE RECONCILED BY A SINGLE RESONANCE HYBRID By CLIVE C. KUENZLE,* MATTHIAS H. WEIBEL,* RENATO R. PELLONI* and PETER HEMMERICHt * Department ofPharmacology and Biochemistry, School of Veterinary Medicine, University ofZurich, CH-8057 Zurich, Switzerland and t Department ofBiology, University ofKonstanz, D-7750 Konstanz, Germany A novel conformational structure of bilirubin is presented which obtains maximum stabilization through a system of four intramolecular hydrogen bonds. Two hydrogen bonds link oxygen and nitrogen atoms of each end ring to the contralateral carboxyl group. The proposed structure can explain a variety of uncommon features of bilirubin, and reconciles many seemingly contradictory hypotheses by accommodating them in individual structures which are mesomeric forms of one resonance hybrid. In the light of this newly conceived structure the following characteristics of bilirubin are re-evaluated: the stability of the compound, its reaction with diazomethane, the conformational beha- viour of its dimethyl ester, its spectral properties, the chirality of the compound when complexed to serum albumin, and the structure of its metal chelates. The basic structure of bilirubin was elucidated by when bilirubin is esterified with diazomethane Fischer's group (Fischer et al., 1941; Fischer & (Kuenzle, 1970a).
    [Show full text]
  • Articles Conformational Analysis of Chirally Deuterated Tunicamycin As an Active Site Probe of UDP-N-Acetylhexosamine:Polyprenol
    13248 Biochemistry 2004, 43, 13248-13255 Articles Conformational Analysis of Chirally Deuterated Tunicamycin as an Active Site Probe of UDP-N-Acetylhexosamine:Polyprenol-P N-Acetylhexosamine-1-P Translocases† Lin Xu,‡ Michael Appell,§,| Scott Kennedy,‡ Frank A. Momany,§,| and Neil P. J. Price*,‡,§,⊥ USDA-ARS-NCAUR, Fermentation Biotechnology Research Unit, and Plant Polymer Research Unit, 1815 North UniVersity Street, Peoria, Illinois 61604, and UniVersity of Rochester Medical Center, 601 Elmwood AVenue, Rochester, New York 14642 ReceiVed August 4, 2004; ReVised Manuscript ReceiVed August 19, 2004 ABSTRACT: Tunicamycins are potent inhibitors of UDP-N-acetyl-D-hexosamine:polyprenol-phosphate N-acetylhexosamine-1-phosphate translocases (D-HexNAc-1-P translocases), a family of enzymes involved in bacterial cell wall synthesis and eukaryotic protein N-glycosylation. Structurally, tunicamycins consist of an 11-carbon dialdose core sugar called tunicamine that is N-linked at C-1′ to uracil and O-linked at C-11′ to N-acetylglucosamine (GlcNAc). The C-11′ O-glycosidic linkage is highly unusual because it forms an R/â anomeric-to-anomeric linkage to the 1-position of the GlcNAc residue. We have assigned the 1H and 13C NMR spectra of tunicamycin and have undertaken a conformational analysis from rotating angle nuclear Overhauser effect (ROESY) data. In addition, chirally deuterated tunicamycins produced 2 by fermentation of Streptomyces chartreusis on chemically synthesized, monodeuterated (S-6)-[ H1]glucose have been used to assign the geminal H-6′a, H-6′b methylene bridge of the 11-carbon dialdose sugar, 4 tunicamine. The tunicamine residue is shown to assume pseudo-D-ribofuranose and C1 pseudo-D- galactopyranosaminyl ring conformers.
    [Show full text]
  • Sc-Homoaromaticity
    This is a repository copy of Modern Valence-Bond Description of Homoaromaticity. White Rose Research Online URL for this paper: https://eprints.whiterose.ac.uk/106288/ Version: Accepted Version Article: Karadakov, Peter Borislavov orcid.org/0000-0002-2673-6804 and Cooper, David L. (2016) Modern Valence-Bond Description of Homoaromaticity. Journal of Physical Chemistry A. pp. 8769-8779. ISSN 1089-5639 https://doi.org/10.1021/acs.jpca.6b09426 Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Modern Valence-Bond Description of Homoaromaticity Peter B. Karadakov; and David L. Cooper; Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K. Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K. Abstract Spin-coupled (SC) theory is used to obtain modern valence-bond (VB) descriptions of the electronic structures of local minimum and transition state geometries of three species that have been con- C sidered to exhibit homoconjugation and homoaromaticity: the homotropenylium ion, C8H9 , the C cycloheptatriene neutral ring, C7H8, and the 1,3-bishomotropenylium ion, C9H11.
    [Show full text]
  • (+)-Belactosin A
    Total Synthesis of (+)-Belactosin A A thesis submitted by James Nicholas Scutt in partial fulfilment of the requirements for the degree of Doctor of Philosophy TT MU r u * 1630444 Heilbron Laboratory Department of Chemistry Imperial College London London SW7 2AY January 2005 Contents Contents 2 Abstract 4 Acknowledgements 5 Abbreviations 6 Stereochemical notation 9 Chapter 1 - Introduction 10 1.1 Isolation and structure of (+)-belactosin A 11 1.2 Proteasome inhibition 12 1.2.1 Biological activity of (+)-belactosin A 12 1.3 Review of previous work 14 1.3.1 De Meijere's synthesis of(2S/R*, I'R, 2'5)-AcpAla 14 1.3.2 Synthesis of a related (isomeric) p-lactone 20 1.4 Recent synthetic work 22 1.4.1 De Meijere's synthesis of AcpAla (all isomers) 23 1.4.2 Vedaras' synthesis of (2S, 1 'R, 2'S)-AcpAla 25 1.4.3 De Meijere's total synthesis of (+)-belactosin A 26 Chapter 2 - Results and discussion 30 2.1 Project aims 31 2.1.1 Synthesis of trans-AcpAla isomers - overview of synthetic strategy 32 2.2 Boronic ester route 34 2.2.1 Introduction 34 2.2.2 Synthesis of cyclopropyl boronic esters 36 2.2.3 Amination of cyclopropyl boronic esters 39 2.3 Epoxide cyclopropanation route 43 2.3.1 Introduction 43 2.3.2. Stereoselectivity and stereospecificity 47 2.3.3 Wadsworth-Emmons aminocyclopropanation 49 2.3.4 Optimisation of Wadsworth-Emmons cyclopropanation 53 2.3.5 Increasing reactivity 59 2.3.6 Room temperature Wadsworth-Emmons cyclopropanation 62 2.3.7 Horner cyclopropanation 64 2.3.8 Asymmetric Wadsworth-Emmons cyclopropanation 65 2.4 Conversion of cyclopropyl
    [Show full text]
  • A Mild and Effective Method for the Conversion of Alkenes Into Alcohols in Subcritical Water
    J. Serb. Chem. Soc. 72 (10) 941–944 (2007) UDC 547.21+547.313:66.094.3:628–032.2 JSCS–3625 Short communication SHORT COMMUNICATION A mild and effective method for the conversion of alkenes into alcohols in subcritical water RECEP OZEN* and NERMN S. KUS Mersin University, Department of Chemistry, Mersin, Turkey (Received 18 December 2006) Abstract: Alkenes were oxidized to alcohols in subcritical water. A number of alke- nes were oxidized directly to their alcohols in excellent yields. The syntheses were performed in 215 cm3 stainless steel high pressure reactor at 120 ºC in 150 cm3 water. The yields of alcohols increased with the nitrogen pressure. Keywords: alkene, alcohol, subcritical water, oxidation. INTRODUCTION Several methods such as oxymercuration, hydroboration, treatment with water in the presence of an acid catalyst and addition of water to olefins in the presence of a transition metal catalyst as well as strong acid catalyzed reactions in subcritical water have been introduced in the literature for the hydration of alkenes.1 Although the conversion of alkenes to alcohols have been known in sub- critical media (Fig. 1),2 many of the methods3 employ strong acids and metal ca- talysts which are not environmentally friendly. The use of subcritical water as a medium for chemical reactions has recently received a great deal of attention.4–5 In contrast to many other solvents, water not only provides a medium for solution chemistry but also often participates in chemical events. Water also offers practi- cal advantages over organic solvents as it is inexpensive, readily available, non- toxic and non-flammable.
    [Show full text]
  • Ethylene Polymerization in Supercritical Carbon Dioxide with Binuclear Nickel(N) Catalysts
    Ethylene polymerization in supercritical carbon dioxide with binuclear nickel(n) catalysts Damien Guironnet, Tobias Friedberger and Steran Mecking* Received 30th June 2009, Accepted 1st September 2009 First published as an Advance Article on the web 21st September 2009 DOl: IO.1039/b912883b A series of new, highly fluorinated neutral (KZ-N,O) chelated Ni(IJ) binuclear complexes based on salicylaldimines bridged in p-position of the N -aryl group were prepared. The complexes are single-component catalyst precursors for ethylene polymerization in supercritical carbon dioxide and toluene. Solubility of the catalyst precursors in supercritical carbon dioxide is effected by a large number of up to 18 trifluoromethyl groups per molecule. Semicrystalline polyethylene with a low degree of branching is formed (ca. 10 branches/WOO carbon atoms). Polymer microstructures are independent of the nature of the bridging moiety, while stability of the catalysts appears to differ. Introduction emulsion systems this can be crucial for the control of nanopartic\e 7d size and structure. ,e Concerning reactions in CO2 , tailoring of the 8 Polymerization of olefins catalyzed by complexes of d metals catalyst precursors to provide solubility in the reaction medium is (late transition metals) has been investigated intensively recently. I required. In comparison to their early transition metal counterparts, We now report binuclear salicylaldiminato Ni(u) methyl com­ they are much more tolerant towards functional groups in the plexes soluble in dense CO2 and their polymerization properties. 2a substrates ,b or reaction media.le Thus, ethylene and I-olefins can be copolymerized with electron-deficient polar vinyl monomers, such as e.g.
    [Show full text]
  • The Synthesis and Reactivity of Heterodinuclear Iron, Ruthenium, and Cobalt Compounds Containing Bridging Dithiomethylene Ligands
    Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1984 The synthesis and reactivity of heterodinuclear iron, ruthenium, and cobalt compounds containing bridging dithiomethylene ligands. Attempted synthesis of the iron carbyne compound Cp(CO)Fe(triple bond)CSCH3 John R. Matachek Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Inorganic Chemistry Commons Recommended Citation Matachek, John R., "The synthesis and reactivity of heterodinuclear iron, ruthenium, and cobalt compounds containing bridging dithiomethylene ligands. Attempted synthesis of the iron carbyne compound Cp(CO)Fe(triple bond)CSCH3 " (1984). Retrospective Theses and Dissertations. 8191. https://lib.dr.iastate.edu/rtd/8191 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages.
    [Show full text]
  • Hydrosilylation of Alkenes Catalyzed by Bis-N-Heterocyclic Carbene Rh(I) Complexes a Density Functional Theory Study
    TECHNISCHE UNIVERSITÄT MÜNCHEN FACHGEBIET FÜR THEORETISCHE CHEMIE Hydrosilylation of Alkenes Catalyzed by Bis-N-Heterocyclic Carbene Rh(I) Complexes A Density Functional Theory Study Dipl. –Chem. Univ. Yin Wu Vollständiger Abdruck der von der Fakultät für Chemie der Technische Universität München zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigten Dissertation. Vorsitzender: Univ.–Prof. Dr. K. Köhler Prüfer der Dissertation: 1. Univ.–Prof. Dr. Dr. h.c. N. Rösch, i. R. 2. Univ.–Prof. Dr. Dr. h.c. B. Rieger Die Dissertation wurde am 14.04.2014 bei der Technischen Universität München eingereicht und durch die Fakultät für Chemie am 08.05.2014 angenommen. i Acknowledgment First and foremost, I want to give my deepest thanks to my Doktorvater, Prof. Dr. Notker Rösch, for giving me the opportunity to do the doctoral thesis in his research group. This dissertation would not have been completed without his guidance and support. Under his supervision, I learned a lot about how to meet academic challenges. The knowledge I gained over these years is very valuable to me. I owe a debt of gratitude to Dr. Alexander Genest, without whose help I would never have learned how to approach a scientific task and resolve essential problems. He also showed me how to communicate efficiently in a team. I am truly thankful to Prof. Dr. Rieger and all colleagues from the Wacker Institute of Silicon Chemistry for the interdisciplinary discussions. It is a pleasure to thank Dr. Virve Karttunen for providing me with the background knowledge about this interesting and complex topic, and for her patience and encouragement, especially in the initial phase of this project.
    [Show full text]