DOCSLIB.ORG

Bindsub 957..994

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Bindsub 957..994 Subject index a acoradiene absinthin 278 – acid-catalyzed cyclization to cedrene 236 – wormwood, isolation from Artemisia acorane–cedrane interconversion 237 absinthium L. 277 acoranes acetic acid – biogenetic relationship to zizaenes 255 – synthesis of 42, 921 acrylates – dianion of 301 – reduction of, with magnesium in methanol acetic acid side chain 442 – by alkylation of ketones 314 acrylic acids – mild hydrolysis of 698 – hydrogenation of 111 a-acetoxy ketone acyl anion equivalent – reduction of, with zinc 546 – generation of 862, 864 acetylation – in maytansine synthesis 857 – lipase-catalyzed 440 acyl anion synthons 188 (+)-acetylcephalotaxine 656 acylation acetyl-CoA 802 – of enamine with mixed anhydride 662 – in biosynthesis of cephalotaxine N-acylhomomeroquinene 534 esters 657 acyliminium cyclization 579 acetylenes acyloin condensation 661 – hydroboration of 379 – Ruhlman modification 662 acetylgynuramine 619 acylpyridines 3-acetyl-2-piperideine – hydrogenation of 771, 784 – acylation with methyl chloroformate 770 3-acylpyridines – by hydrogenation of 3-acetyl-pyridine 770 – hydrogenation to vinylogous amide 592 3-acetylpyridine – in general method of synthesis 195, 196, – hydrogenation of 592, 593, 770 593 – in indole alkaloid synthesis 195, 196, 771, 3-acylpyridinium salts 776 – acid-catalyzed cyclization of 593, 782 aconitine 530, 531, 847, 848 – in alkaloid synthesis 195, 196, 592 The Way of Synthesis. TomÐ Hudlick and Josephine W. Reed Copyright 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-31444-7 958 Subject index N-acyl vinylogous urea – of keto ester dianion 435 – attachment of, in palytoxin synthesis 901 1,4-alkylative dearomatization Adam’s catalyst 260, 375, 376, 397, 609, 626 – in cedrene synthesis 234 – hydrogenation of limonene 399 alkylative transposition aflatoxin 847 – of 1,3-carbonyl 664 aflatoxin B1 846 alkyl zinc b-agarofuran – addition to ketone 484 – synthesis 113 – in quassin synthesis 484 AIDS Alloferine 801 – treatment of 910 allyl ether ajmalicine 541, 542, 761 – reductive fission of 299 – in biosynthesis of indole alkaloids 762 allylic alcohols ajmaline 541, 542 – by reduction of malonates 316, 317 alcohol dehydrogenase – directed hydrogenation of 512 – in desymmetrization of meso diols 117 – from epoxides 485 alcyonin 5 – oxidation with MnO2 317 – structure revision 4 – reductive transposition of 488 aldehyde synthesis – by reduction of epoxy mesylates 317 – by hydrolysis of gem-dichloride to 782 allylic bromination 383 aldolase allylic carbamate displacement 741, 742 – in enzymatic aldol condensation 116 – suprafacial 742 aldol condensation 48, 292, 451, 453, 462, 664, – with lithiosilanes 741 766 allylic epoxidation 508 – asymmetric 55, 56 allylic oxidation 400, 472, 474, 476, 477, 509 – in damsin synthesis 305, 306 – chemoselective 310 – intramolecular 306, 583, 776 – of 1,4-diene to dienone 786 – in aspidospermidine synthesis 776 – of olefin to enone 556, 785 – in zizaene synthesis 261 – with 1,3-oxygen shift 352 – transition state model 57 – with retention of olefin regiochemistry alexine 639, 641 588 alizarin – with selenium dioxide 591 – synthesis 41, 42 p-allylnickel complex 319 alkaloid allyloxycarbonyl (ALOC) – origin of the word 527 – reduction of 182 alkaloids 5 allylsilane cyclization – chronology of isolation 528 – of acylimminium ion 627, 743 – general methods of synthesis 767 Amaryllidaceae constituents b-alkoxygenone synthesis 854 – bibliography 721 alkylation – biological acitivites of 689 – a vs. c control 168, 259, 260 – biosynthesis of 689, 691 – C vs. O control 168 – isolation 689 – C vs. O vs. N control 168 – structura 689 – of carbonyl compounds 167 – synthesis of ent-series 720 – of crotonates 167 ambrosin 278 a-alkylation americanolide 278 – of enone 511 amide reduction – of unsaturated ester 608 – via imino chloride 633 a-alkylation vs. c-alkylation amino cyclitols – of enones 259, 260 – synthesis of 155 Subject index 959 amino hydroxylation 58 – isolation from Cephalosporium aphidicola – asymmetric 641 Petch 449 aminoindanol – isolation from Nigrospora sphaerica 449 – from indane cis-diol 912 – synthesis of 104 (+)–(S)-amphetamine 529 – total synthesis, Corey 455 amphidinolide B 871 – total synthesis, Holton 105, 461 – synthesis of 869 – total synthesis, Ireland 456 (+)-amphidinolide W – total synthesis, McMurry 451 – synthesis of 869 – total synthesis, Trost 451 – revision of structure 871 D-arabinose amprenavir 911 – Kiliani–Fischer chain extension 24 – HIV-I protease inhibitor 910 – proof of stereochemistry 25 androsterone 208 arboflorine 849, 850 anionic cyclization arborescin 278, 295 – of alkoxides to enynes 293 arene–olefin cycloaddition 241, 389, anionic oxygenation 390, 420 – of benzylic carbon 540 – in retigeranic acid synthesis 400 anionic rearrangement – photochemical 372 – of imino esters 633 – in cedrene synthesis 239 a-anion synthons 188 aromadendrene 277, 278 anisole (–)-aromadendrene 325 – demethylation of 735 aromatic dihydroxylation 136 – oxidative cleavage 576, 579 aromatic substitution annopodine 574 – photostimulated 663 annotine 574 aromatin 278 annotinine 574 aromatization 854 – synthesis of 588 aspartyl protease – Wiesner’s synthesis 590 – inhibition of 911 [4+1] annulation 104, 406 aspidoalbine 760 – intramolecular of dienic aspidophytine 780 diazoketones 403 – total synthesis, Padwa 779 [3+2] annulation Aspidosperma alkaloids 761, 763, 764, 820 – in triquinane design 363 – approaches to 775 ansa compounds – general method of synthesis 769, 770, 772, – definition of 879 773, 776, 794 – history of 879 – structure elucidation 780 ansomytocins 851 – chemical interconversion of 764 antascomicin A 871 aspidospermidine 530, 760, 761, 764, 770, 772, – synthesis of 869 773, 776, 780, 794, 815 antascomicin B 871 – bibliography 826 1,4-anti elimination – conversion to vincadifformine 773 – of HBr, in diene synthesis 443 – disconnection analysis 765 aphidicolin 213, 449, 453, 454, 455, 463 – total synthesis, Aube 773 – asymmetric formal synthesis of 461 – total synthesis, Heathcock 775 – bibliography 464 – total synthesis, Kutney 775 – biogenetic-type synthesis 456 – total synthesis, Magnus 775 – biological activity of 449 – total synthesis, Schultz 786 – biomimetic approaches to synthesis 451 – total synthesis, Wenkert 767 – disconnection analysis 450 – total synthesis, Zard 775 960 Subject index (–)-aspidospermidine – synthesis 244 – asymmetric synthesis of 786 – radical cascade of 243, 246 aspidospermine 531, 759, 760, 780, 921 azulene – bibliography 826 – from oil of chamomile 277 – comparison of Stork’s and Ban’s intermediates 767, 768 b – dehydrogenation with zinc dust 31 baccatin III 13, 499, 500 – disconnection analysis 765 – esterification of 507 – Emde degradation of 34 – symmetry-based design 151 – fragmentation of 32 Baeyer–Villiger reaction 118, 308, 309, 321, – Hofmann degradation of 34 485, 555, 556, 557, 560, 579, 705, 720 – isolation from Aspidosperma quebracho – asymmetric 59 blanco 764 – Hudrlik silicon-directed version 785, 786 – oxidation of 32 – in eburnamonine synthesis 786 – structure proof 23, 31 – in quassin synthesis 483 – total synthesis, Stork 765 baker’s yeast reduction – Xray structure 32 – of keto esters 639 Asteraceae families of plants barbatusol 488 – source of pyrrolizidine alkaloids 617 Barton–McCombie deoxygenation 246, 381, asymmetric oxidation 54, 110, 112, 117, 118 383, 388, 404, 409, 419 asymmetric reduction 110 Barton reaction 112 – of enones 667 Baylis–Hillman reaction 578 – with chiral oxazaborolidine catalysts 110, – of ethyl acrylate with 488, 667 m-methoxybenzaldehyde 577 atom economy 96, 727 Beckmann rearrangement 47, 48, 595, 800 – definition of 97 – in ibogamine synthesis 799 atom transposition – of dihydrocodeinone oxime 30 – in cyclic compounds 176 – Barton nitrone version 311, 313 atropine 529, 531 benzene atropoisomerism – chemical oxygenation of 119 – in vancomycin 873 – synthesis from acetylene 214 – in pancratistatin synthesis 698 – asymmetric dihydroxylation of 118 australine 639, 641 benzocyclobutane (+)-australine – cycloreversion 114 – total synthesis, Denmark 639 – in steroid synthesis 209 azabicyclo[3.3.0]octane 619 benzyl ether – disconnective strategies 620 – deprotection with BBr3 352 aza-Diels–Alder reaction N-benzoylmeroquinene 537 – in daphnilactone synthesis 609 o-benzyloxime 709 azadiene formation 609 benzyne alkylation aza–ene reaction – intramolecular 661 – of acylimminium ion 627 benzyne generation azaspiracid-1 6 – with sodium or potassium amide 663 – structure revision 5 Bergman cycloaromatization aza sugars – of ene-diyne subunit 873 – synthesis of 155 Beyermann–Grewe cyclization 737 azide–diene cycloaddition 636 bicyclic ketones N-aziridinyl imine – stability relationships in 177, 179, 180, – in radical cyclization 267 181, 279 Subject index 961 bicyclo[2.2.1]heptane bis(dihydroquinidino)–phthalazine – fragmentation of 308 – in asymmetric amino-hydroxylation 641 – in hydrazulene synthesis 307 1,2-bis(trimethylsiloxy)cyclobutane 663 bicyclo[2.2.2]octanone Bohlman–Wenkert bands – via a Diels–Alder reaction 560 – IR frequencies 576 bicyclo[2.2.2]octene – in structure elucidation of heterocycles – cleavage of 484 575 bicyclo[3.2.1]octanone bond-set analysis 130 – synthesis of 463 Boraginaceae families of plants bicyclo[3.2.1]oxaoctane – source of pyrrolizidine alkaloids 617 – in phorbol synthesis 470, 471 (–)-borneol 507, 517, 518 bicyclo[3.3.1]nonanone Bredt’s rule 588 – synthesis of 586 brevenal 874 bicyclo[3.3.0]octanes – biological activity
Load more

Recommended publications
  • Brittain-DR-1965-Phd-Thesis.Pdf
    POLYMETHYLENE PYRIDINES , A thesis submitted by David Robert Brittain in partial fulfilment of the requirements for the degree of DOCTOR OP PHILOSOPHY in the University of London Organic Chemistry Department, dune, 1965. Imperial College, LONDON, S.W.7. ABSTRACT This thesis describes a series of attempts to syn- thesise 2,5- and 1,4-polymethylene bridged pyridines. Nuclear magnetic resonance theory predicts that protons, which are held directly over an aromatic ring, will be abnormally shielded compared with protons in aliphatic straight-chain hydrocarbons. This prediction has been verified for the central methylene protons of paracyclo- phanes. The degree of shielding, expressed in terms of the distance from the aromatic ring, is a measure of the induced ring current and hence the aromaticity of the benzene ring. Similar measurements upon 2,5- or 1,4— polymethylene bridged pyridines would make it possible to determine the degree of aromaticity of the pyridine ring relative to benzene. A review of the subject of aromaticity is presented in which special reference has been made to its inter- pretation by nuclear magnetic resonance. The synthetic work has not been brougL.t to a truly satisfactory conclusion. However, the synthetic routes to 2,5-dialkylpyridines have been thoroughly investigated and a wide variety of such compounds prepared. The functional groups at the ends of the alkyl chains have been varied in an effort to produce a derivative which would cyclise to give a 2,5-bridged pyridine. The attempted intramolecular oxidative coupling of 2,5-dihex- 51 -ynylpyridine received much attention. In the attempts to obtain a 1,4-bridged pyridine, two tricyclic compounds, each containing two quaternised pyridine rings linked by polymethylene chains, were obtained.
    [Show full text]
  • The Development and Application of Metal-Catalyzed Processes for Organic Synthesis
    The Development and Application of Metal-Catalyzed Processes for Organic Synthesis by Edward J. Hennessy B.A. Chemistry Northwestern University, 2000 Submitted to the Department of Chemistry in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY IN ORGANIC CHEMISTRY at the Massachusetts Institute of Technology June 2005 © 2005 Massachusetts Institute of Technology All Rights Reserved Signature of Author: " - - 1_"' .Da-uirnt of Chemistry May 19, 2005 Certified by: Stephen L. Buchwald Camille Dreyfus Professor of Chemistry Thesis Supervisor Accepted by: Robert W. Field Chairman, Departmental Committee on Graduate Students ARCHIVES: This doctoral thesis has been examined by a committee of the Department of Chemistry as follows: -/ Professor Gregory C. Fu: " Ch Chair Professor Stephen L. Buchwald Thesis Supervisor Professor Timothy M. Swager: , -L i \ O 2 The Development and Application of Metal-Catalyzed Processes for Organic Synthesis by Edward J. Hennessy Submitted to the Department of Chemistry on May 19, 2005 in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy at the Massachusetts Institute of Technology ABSTRACT Chapter 1. Copper-Catalyzed Arylation of Stabilized Carbanions A mild, general catalytic system for the synthesis of a-aryl malonates has been developed. Aryl iodides bearing a variety of functional groups can be effectively coupled to diethyl malonate in high yields using inexpensive and widely available reagents, making this a superior method to those previously described that employ copper reagents or catalysts. The functional group tolerance of the process developed makes it complementary to analogous palladium-catalyzed couplings. Importantly, a set of mild reaction conditions has been developed that minimize product decomposition, a problem that had not been addressed previously in the literature.
    [Show full text]
  • Nucleophilic Aromatic Substitution
    NUCLEOPHILIC AROMATIC SUBSTITUTION Ms. Prerana Sanas M.Pharm (Pharmceutical Chemistry) Asst.Professor, NCRD’s Sterling Institute of Pharmacy Nerul Navi Mumbai Nucleophilic aromatic substitution results in the substitution of a halogen X on a benzene ring by a nucleophile (:Nu– ). Aryl halides undergo a limited number of substitution reactions with strong nucleophiles. NAS occurs by two mechanisms i) Bimoleccular displacement (Addition –Elimination) ii) Benzyne Formation( Elimination –Addition) 7/5/2019 Ms.Prerana Sanas 2 Bimolecular displacement (Addition – Elimination) Aryl halides with strong electron-withdrawing groups (such as NO2) on the ortho or para positions react with nucleophiles to afford substitution products. For example, treatment of p-chloronitrobenzene with hydroxide (– OH) affords p-nitrophenol by replacement of Cl by OH. Nucleophilic aromatic substitution occurs with a variety of strong nucleophiles, including – OH, – OR, – NH2, – SR, and in some cases, neutral nucleophiles such as NH3 and RNH2 . 7/5/2019 Ms.Prerana Sanas 3 Mechanism…… The mechanism of these reactions has two steps: Step i) Addition of the nucleophile (:Nu– ) forms a resonance-stabilized carbanion with a new C – Nu bond—three resonance structures can be drawn. • Step [1] is rate-determining since the aromaticity of the benzene ring is lost. In Step ii) loss of the leaving group re-forms the aromatic ring. This step is fast because the aromaticity of the benzene ring is restored. 7/5/2019 Ms.Prerana Sanas 4 Factors affecting Bimolecular displacement Increasing the number of electron-withdrawing groups increases the reactivity of the aryl halide. Electron-withdrawing groups stabilize the intermediate carbanion, and by the Hammond postulate, lower the energy of the transition state that forms it.
    [Show full text]
  • The Total Synthesis of Securinine and Other Methodology Studies
    University of Windsor Scholarship at UWindsor Electronic Theses and Dissertations Theses, Dissertations, and Major Papers 2010 The total synthesis of securinine and other methodology studies Bhartesh Dhudshia University of Windsor Follow this and additional works at: https://scholar.uwindsor.ca/etd Recommended Citation Dhudshia, Bhartesh, "The total synthesis of securinine and other methodology studies" (2010). Electronic Theses and Dissertations. 8275. https://scholar.uwindsor.ca/etd/8275 This online database contains the full-text of PhD dissertations and Masters’ theses of University of Windsor students from 1954 forward. These documents are made available for personal study and research purposes only, in accordance with the Canadian Copyright Act and the Creative Commons license—CC BY-NC-ND (Attribution, Non-Commercial, No Derivative Works). Under this license, works must always be attributed to the copyright holder (original author), cannot be used for any commercial purposes, and may not be altered. Any other use would require the permission of the copyright holder. Students may inquire about withdrawing their dissertation and/or thesis from this database. For additional inquiries, please contact the repository administrator via email ([email protected]) or by telephone at 519-253-3000ext. 3208. The Total Synthesis of Securinine and Other Methodology Studies by Bhartesh Dhudshia A Dissertation Submitted to the Faculty of Graduate Studies through the Department of Chemistry and Biochemistry in Partial Fulfillment of the Requirements
    [Show full text]
  • Organic Synthesis: New Vistas in the Brazilian Landscape
    Anais da Academia Brasileira de Ciências (2018) 90(1 Suppl. 1): 895-941 (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690 http://dx.doi.org/10.1590/0001-3765201820170564 www.scielo.br/aabc | www.fb.com/aabcjournal Organic Synthesis: New Vistas in the Brazilian Landscape RONALDO A. PILLI and FRANCISCO F. DE ASSIS Instituto de Química, UNICAMP, Rua José de Castro, s/n, 13083-970 Campinas, SP, Brazil Manuscript received on September 11, 2017; accepted for publication on December 29, 2017 ABSTRACT In this overview, we present our analysis of the future of organic synthesis in Brazil, a highly innovative and strategic area of research which underpins our social and economical progress. Several different topics (automation, catalysis, green chemistry, scalability, methodological studies and total syntheses) were considered to hold promise for the future advance of chemical sciences in Brazil. In order to put it in perspective, contributions from Brazilian laboratories were selected by the citations received and importance for the field and were benchmarked against some of the most important results disclosed by authors worldwide. The picture that emerged reveals a thriving area of research, with new generations of well-trained and productive chemists engaged particularly in the areas of green chemistry and catalysis. In order to fulfill the promise of delivering more efficient and sustainable processes, an integration of the academic and industrial research agendas is to be expected. On the other hand, academic research in automation of chemical processes, a well established topic of investigation in industrial settings, has just recently began in Brazil and more academic laboratories are lining up to contribute.
    [Show full text]
  • Reactions of Aromatic Compounds Just Like an Alkene, Benzene Has Clouds of  Electrons Above and Below Its Sigma Bond Framework
    Reactions of Aromatic Compounds Just like an alkene, benzene has clouds of electrons above and below its sigma bond framework. Although the electrons are in a stable aromatic system, they are still available for reaction with strong electrophiles. This generates a carbocation which is resonance stabilized (but not aromatic). This cation is called a sigma complex because the electrophile is joined to the benzene ring through a new sigma bond. The sigma complex (also called an arenium ion) is not aromatic since it contains an sp3 carbon (which disrupts the required loop of p orbitals). Ch17 Reactions of Aromatic Compounds (landscape).docx Page1 The loss of aromaticity required to form the sigma complex explains the highly endothermic nature of the first step. (That is why we require strong electrophiles for reaction). The sigma complex wishes to regain its aromaticity, and it may do so by either a reversal of the first step (i.e. regenerate the starting material) or by loss of the proton on the sp3 carbon (leading to a substitution product). When a reaction proceeds this way, it is electrophilic aromatic substitution. There are a wide variety of electrophiles that can be introduced into a benzene ring in this way, and so electrophilic aromatic substitution is a very important method for the synthesis of substituted aromatic compounds. Ch17 Reactions of Aromatic Compounds (landscape).docx Page2 Bromination of Benzene Bromination follows the same general mechanism for the electrophilic aromatic substitution (EAS). Bromine itself is not electrophilic enough to react with benzene. But the addition of a strong Lewis acid (electron pair acceptor), such as FeBr3, catalyses the reaction, and leads to the substitution product.
    [Show full text]
  • AROMATIC NUCLEOPHILIC SUBSTITUTION-PART -2 Electrophilic Substitution
    Dr. Tripti Gangwar AROMATIC NUCLEOPHILIC SUBSTITUTION-PART -2 Electrophilic substitution ◦ The aromatic ring acts as a nucleophile, and attacks an added electrophile E+ ◦ An electron-deficient carbocation intermediate is formed (the rate- determining step) which is then deprotonated to restore aromaticity ◦ electron-donating groups on the aromatic ring (such as -OH, -OCH3, and alkyl) make the reaction faster, since they help to stabilize the electron-poor carbocation intermediate ◦ Lewis acids can make electrophiles even more electron-poor (reactive), increasing the reaction rate. For example FeBr3 / Br2 allows bromination to occur at a useful rate on benzene, whereas Br2 by itself is slow). In fact, a substitution reaction does occur! (But, as you may suspect, this isn’t an electrophilic aromatic substitution reaction.) In this substitution reaction the C-Cl bond breaks, and a C-O bond forms on the same carbon. The species that attacks the ring is a nucleophile, not an electrophile The aromatic ring is electron-poor (electrophilic), not electron rich (nucleophilic) The “leaving group” is chlorine, not H+ The position where the nucleophile attacks is determined by where the leaving group is, not by electronic and steric factors (i.e. no mix of ortho– and para- products as with electrophilic aromatic substitution). In short, the roles of the aromatic ring and attacking species are reversed! The attacking species (CH3O–) is the nucleophile, and the ring is the electrophile. Since the nucleophile is the attacking species, this type of reaction has come to be known as nucleophilic aromatic substitution. n nucleophilic aromatic substitution (NAS), all the trends you learned in electrophilic aromatic substitution operate, but in reverse.
    [Show full text]
  • Aryl Halides
    Block 3 Aromatic Hydrocarbons and Halogen Derivatives UNIT14 ARYL HALIDES Structure 14.1 Introduction Electophilic Substitution Reactions Expected Learning Outcomes 14.2 Structure and Reactivity Reactions due to C−X bond 14.5 Reactivity and Relative 14.3 Preparation of Aryl Halides Strength of C−X Bonds in 14.4 Reaction of Aryl Halides Halogen Derivatives Nucleophilic Substitution by 14.6 Summary Addition-Elimination 14.7 Terminal Questions Nucleophilic Substitution via 14.8 Answers Benzene Intermediate 14.1 INTRODUCTION In Unit 13, we have pointed out that there is a difference in the nature of C−X bond of aryl halides and aryl halides. Because of this aryl halides differ from the alkyl halides in their preparation and properties. In this Unit, we will study the unique chemistry of aryl halides. First, we shall take up the structure and reactivity of aryl halides, which is followed by their preparations and properties. At the end of the unit we shall compare the reactivity and relative strength of C−X bond in different type of halogen derivatives. Expected Learning Outcomes After studying this unit, you should be able to: explain why aryl halides are less reactive than alkyl halides, outline the methods of preparation of aryl halides, describe the reactions of aryl halides, and explain the difference in structure and reactivity of alkyl, alkenyl and aryl halides towards nucleophilic substitution reactions. 94 Unit 14 Aryl Halides 14.2 STRUCTURE AND REACTIVITY Before going into the details of the preparations and properties of aryl halides let us take a look at the structure and reactivity of these compounds so that we can understand why their reactions are different from alkyl halides.
    [Show full text]
  • Aromatic Substitution Reactions: an Overview
    Review Article Published: 03 Feb, 2020 SF Journal of Pharmaceutical and Analytical Chemistry Aromatic Substitution Reactions: An Overview Kapoor Y1 and Kumar K1,2* 1School of Pharmaceutical Sciences, Apeejay Stya University, Sohna-Palwal Road, Sohna, Gurgaon, Haryana, India 2School of Pharmacy and Technology Management, SVKM’s NMIMS University, Hyderabad, Telangana, India Abstract The introduction or replacement of substituent’s on aromatic rings by substitution reactions is one of the most fundamental transformations in organic chemistry. On the basis of the reaction mechanism, these substitution reactions can be divided into electrophilic, nucleophilic, radical, and transition metal catalyzed. This article also focuses on electrophilic and nucleophilic substitution mechanisms. Introduction The replacement of an atom, generally hydrogen, or a group attached to the carbon from the benzene ring by another group is known as aromatic substitution. The regioselectivity of these reactions depends upon the nature of the existing substituent and can be ortho, Meta or Para selective. Electrophilic Aromatic Substitution (EAS) reactions are important for synthetic purposes and are also among the most thoroughly studied classes of organic reactions from a mechanistic point of view. A wide variety of electrophiles can effect aromatic substitution. Usually, it is a substitution of some other group for hydrogen that is of interest, but this is not always the case. For example, both silicon and mercury substituent’s can be replaced by electrophiles. The reactivity of a particular electrophile determines which aromatic compounds can be successfully substituted. Despite the wide range of electrophilic species and aromatic ring systems that can undergo substitution, a single broad mechanistic picture encompasses most EAS reactions.
    [Show full text]
  • JUN 1 51998 Science
    Efforts Toward the Syntheses of Natural Products: Part A: Paeoniflorin Part B: (+)-Taxusin A thesis presented by Rebecca J. Carazza B.S. Chemistry University of Massachusetts, Amherst, 1993 Submitted to the Department of Chemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry at the Massachusetts Institute of Technology June 1998 © 1998 Massachusetts Institute of Technology. All rights reserved. SinatureofAuthor: SignatureT- -~- -- .. -uof -Author: -- I- ----- D4pdrtment o('ihemistry May 26, 1998 Certified by: ,Scott C. Virgil Thesis Advisor Acceuted bv: Dietmar Seyferth Chairman, Departmental Committee on Graduate Students O-V .Z\ . JUN 1 51998 Science UR PAES This doctoral thesis has been examined by a committee of the Department of Chemistry as follows: Professor Rick L. Danheiser - Chairman Professor Scott C. Virgil / Th/sis Supervisor Professor Peter H. Seeberger Efforts Toward the Syntheses of Natural Products: Part A: Paeoniflorin Part B: (+)-Taxusin by Rebecca J. Carazza Submitted to the Department of Chemistry on May 26, 1998 in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry Massachusetts Institute of Technology ABSTRACT Part A Efforts toward the synthesis of the monoterpene glycoside paeoniflorin (1) are discussed. Optimization of the previous synthetic route was successful. Synthesis of the key cc-diazo intermediate 30 was achieved and the construction of the carbocyclic frame was completed. Key reactions of the strategy involve a ring contraction via a Wolff rearrangement, and formation of the lactone 78 which undergoes diisobutylaluminum hydride reduction followed by acid catalyzed cyclization to the paeoniflorin ring system 80. A new synthetic strategy was initiated to prepare the key [3.2.1]bicyclooctanone 81 using a palladium mediated olefin cyclization of the acyloin substrate 82.
    [Show full text]
  • Syntheses of Morphine and Codeine (1992 – 2002): Templates for Exploration of Synthetic Tools
    Current Organic Synthesis, 2006, 3, 99-120 99 Syntheses of Morphine and Codeine (1992 – 2002): Templates for Exploration of Synthetic Tools L. M. Mascavage#, M. L. Wilson and D. R. Dalton* Department of Chemistry (016-00), Beury Hall, 13th and Norris Streets, Temple University, Philadelphia, PA 19122, USA and Department of Chemistry, Arcadia University, Glenside, PA, 19038, USA Abstract: Morphine (1) and its O-methylated analogue codeine (2), analgesic alkaloids of the opium poppy (Papaver Somniferium), have been targets of organic chemists engaged in synthetic activities for at least half a century. The “first” (Gates) and “most efficient” (Rice) syntheses of morphine (1) and codeine (2) are well known and have been reviewed and analyzed extensively numerous times. However, syntheses of the same two alkaloids that have been reported since 1992 and which have been used as devices to advance the art of organic synthesis are not as widely recognized and they have not been as thoroughly reviewed. Here they are analyzed in the spirit of the use of these two compounds as templates. Further, since both racemic and enantiospecific syntheses are important and since all eight (8) approaches (since 1992) are sufficiently different so as to warrant more tha n superficial examination, they are all considered. H HO 7 H 8 15 6 H H 6 14 N 5 CH3 H 13 NCH3 HO 14 13 9 16 9 O 16 12 15 10 O 10 4 4 11 1, R = H 2, R = CH 1 1 3 RO 3 RO 3 2 2 It is nearly two hundred years since the initial report the ubiquitous standard opium poppy or with cultivars that (1806) of the isolation of morphine (1, R = H) from the might be subsequently generated through genetic unripe seed pods of the opium poppy, Papever somniferum, manipulations so as to maximize production of these or by Friedrich Wihelm Adam Setürner [1], seventy five years related bases.
    [Show full text]
  • Simple, Efficient Catalyst System for the Palladium-Catalyzed Amination of Aryl Chlorides, Bromides, and Triflates
    1158 J. Org. Chem. 2000, 65, 1158-1174 Simple, Efficient Catalyst System for the Palladium-Catalyzed Amination of Aryl Chlorides, Bromides, and Triflates John P. Wolfe,† Hiroshi Tomori, Joseph P. Sadighi,‡ Jingjun Yin, and Stephen L. Buchwald* Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Received October 29, 1999 Palladium complexes supported by (o-biphenyl)P(t-Bu)2 (3)or(o-biphenyl)PCy2 (4) are efficient catalysts for the catalytic amination of a wide variety of aryl halides and triflates. Use of ligand 3 allows for the room-temperature catalytic amination of many aryl chloride, bromide, and triflate substrates, while ligand 4 is effective for the amination of functionalized substrates or reactions of acyclic secondary amines. The catalysts perform well for a large number of different substrate combinations at 80-110 °C, including chloropyridines and functionalized aryl halides and triflates using 0.5-1.0 mol % Pd; some reactions proceed efficiently at low catalyst levels (0.05 mol % Pd). These ligands are effective for almost all substrate combinations that have been previously reported with various other ligands, and they represent the most generally effective catalyst system reported to date. Ligands 3 and 4 are air-stable, crystalline solids that are commercially available. Their effectiveness is believed to be due to a combination of steric and electronic properties that promote oxidative addition, Pd-N bond formation, and reductive elimination. Owing to the many important applications of aniline derivatives, and the limitations of most methods for their synthesis, a considerable amount of effort has been recently devoted to the development of catalysts that are capable of effecting the cross-coupling of amines with aryl halides and sulfonates.1 However, the proper choice of catalyst (Pd source, ligand choice) is crucial for the success of these reactions.
    [Show full text]