Cycloaddition

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  Microwave-Assisted Organic Synthesis

  A Green Chemical Approach

  • Suresh C. Ameta, Pinki B. Punjabi, Rakshit Ameta, Chetna Ameta, Suresh C. Ameta, Pinki B. Punjabi, Rakshit Ameta, Chetna Ameta(Authors)
  • 2014(Publication Date)
  • Apple Academic Press

    (Publisher)

  CHAPTER 8 Cycloaddition ABHILASHA JAIN, K. L. AMETA, PINKI B. PUNJABI, and SURESH C. AMETA CONTENTS 8.1 [2+2] Cycloaddition ......................................................................... 132 8.2 1,3-Dipolar Addition ........................................................................ 135 8.3 [4+2] Cycloaddition ......................................................................... 146 8.4 Other Cycloadditions ....................................................................... 157 Keywords .................................................................................................. 160 References ................................................................................................. 160 132 Microwave-Assisted Organic Synthesis: A Green Chemical Approach A Cycloaddition reaction is a pericyclic reaction in which two or more unsaturated compounds combine with the formation of a cyclic adduct. Cycloaddition reactions have been greatly benefited from the use of microwave irradiation not only by com-pleting the reactions in few minutes, but avoiding many of the disadvantages of the conventional reaction conditions like solvent evaporation and poor yield. As MORE (Microwave organic reaction enhancement) chemistry provides cleaner re-action products as well as conditions for carrying out those reactions, which are unattainable under conventional heating conditions. Microwave-assisted cycloaddi-tion reactions give rapid access to fused multicyclic and heterocyclic systems in a single step process.

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  Asymmetric Synthesis V3

  • James Morrison(Author)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  7 Asymmetric Cycloaddition Reactions Leo Λ. Paquette Department of Chemistry The Ohio State University Columbus, Ohio I. Introduction 455 II. Intermolecular Diels-Alder Reactions 456 A. Chiral Dienophiles in the Absence of Catalysis 456 B. Chiral Dienophiles: Lewis Acid Catalysis 467 C. Chiral Dienophiles: Influence of Pressure 471 D. Chiral Dienes 474 E. Chiral Catalysts 477 III. Intramolecular Diels-Alder Processes 478 IV. [2 + 2] Cycloadditions 483 A. Enamine-Sulfene Condensations 483 B. Asymmetric Synthesis of β-Lactams, β-Lactones, and Cyclobutanones 484 C. Photochemical Formation of Oxetanes and Thietanes . . . 489 D. Cyclobutane Formation 492 V. [3 + 2] Cycloadditions 493 A. Optically Active Cyclopropanes by Diazoalkane Addition . 493 B. Optically Active Cyclopropanes by Other Routes 496 C. Isoxazolidines from Nitrones 496 References 498 I. Introduction The importance of asymmetric organic reactions to organic chemistry lies in their capacity to produce optically active compounds and to serve as a diagnostic tool for the study of reaction mechanisms. The special role of ASYMMETRIC SYNTHESIS VOLUME 3 455 Copyright © 1984 by Academic Press, Inc. All rights of reproduction in any form reserved. ISBN 0-12-507703-3 456 L. A. Paquette Cycloaddition reactions derives from the fact that two new σ bonds are formed in these processes. Consequently, when coupling between carbon atoms is involved, enantioselective carbon-carbon bond formation can operate to produce two pairs of new chiral centers. Efficient control of stereochemistry at these sites is a formidable challenge. Nonetheless, progress in the field has been encouraging. In an asymmetric Cycloaddition reaction, a substrate containing a dou-ble bond combines with a reagent capable of engaging in a [4 + 2], [3 + 2], [2 + 2], or [2 + 1] bonding scheme to generate two diastereomeric transition states.

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  Organic Reaction Mechanisms 2018

  An Annual Survey Covering the Literature Dated January to December 2018

  • Mark G. Moloney(Author)
  • 2021(Publication Date)
  • Wiley

    (Publisher)

  413 11 Addition Reactions: Cycloaddition N. Dennis 3 Camphorlaurel Crt, Stretton, Queensland, 4116 Australia CHAPTER MENU [2 + 2]-Cycloaddition, 418 [2 + 3]-Cycloaddition, 420 [2 + 4]-Cycloaddition, 430 Miscellaneous Cycloadditions, 439 References, 446 The recent achievements in catalytic Cycloadditions of 1, n -dipoles in the synthesis of medium-sized carbo-and heterocyclic compounds has been reviewed. 1 A review of the Cycloadditions between o -carboranes and o -carborynes with unsaturated compounds, alkenes, polycyclic or heterocyclic aromatics, in the past ten years, has been pre-sented. The reaction mechanisms of o -carboryne-involved [2 + 2 + 2]-, [2 + 2 + 1]-, [2 + 2]-, [3 + 2]-, [4 + 2]-and [5 + 2]-Cycloadditions are discussed. 2 The K 2 CO 3 -promoted ring-closing carbonyl-allene metathesis reaction of N -allenyl-𝛽 -enaminones produced 2,4-disubstituted pyrroles with cleavage of the C( sp )-C( sp 3 ) bond. A stepwise [2 + 2]-Cycloaddition/retro [2 + 2]-reaction mechanism has been proposed. 3 The Fe(III)-catalyzed bicyclization of yne-allenones ( 1 ) with indoles ( 3 ) furnished cyclobuta [ a ]naphthalen-4-ols ( 4 ) in good to excellent yields. The reaction mechanism is thought to proceed through an initial intramolecular [2 + 2]-Cycloaddition followed by a 1,6-conjugate addition. The key intermediate is a cyclobutene adduct ( 2 ) (Scheme 1). 4 The rhodium-catalyzed intramolecular Cycloaddition of electron ( e )-deficient 2-phenylnaph-thalene-linked triynes ( 5 ), possessing carbonyl groups at the alkyne termini, yielded [2 + 2 + 2]-and [2 + 1 + 2 + 1]-cycloadducts ( 6 , 7 ) depending on the nature of the carbonyl groups on the alkyne termini. Thus, when the triyne possesses bulky and e -withdrawing isobutanoyl and pivaloyl groups, only [2 + 1 + 2 + 1]-cycloadducts are formed. However, when the triyne has highly coordinating dimethoxycarbamoyl groups, the [2 + 2 + 2]-cycloadducts formed exclusively (Scheme 2).

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  The Conservation of Orbital Symmetry

  • R. B. Woodward, R. Hoffmann(Authors)
  • 2013(Publication Date)
  • Academic Press

    (Publisher)

  (133) 66 6. Theory of Cycloadditions and Cycloreversions A priori, there are in fact four possible modes of combination of the termini of two unlike components in a Cycloaddition reaction. Each mode has a characteristic stereochemical consequence, displayed in Figure 21. m-2 Y X -y γ -: X m-2 -Y Y > X Figure 21. Stereochemical consequences of two-component Cycloadditions. The dia-grams are purely schematic, and do not reflect the actual geometry of the transition states, which of course differs markedly from case to case. Note that there are two possi-ble supra y supra cases when m or «> 2, differing in the mode of approach of the reactants [exo and endo additions]. Similar circumstances obtain in the other cases. When the two reactants are identical the supra t antara and the antara^upra processes are indistinguish-able. 6 . Theory of Cycloadditions and Cycloreversions 67 In using the principle of orbital symmetry conservation to determine whether any Cycloaddition is symmetry-allowed or forbidden, a complete analysis requires that all orbitals — bonding and antibonding — be considered. But a simplified proce-dure is often useful. First, all relevant reactant electrons are placed in fully delocal-ized bonding a molecular orbitals of the product of the Cycloaddition under exami-nation. Then, if the electrons occupying the a orbitals can be moved into bonding orbitals of the products of the cycloreversion when the a bonds are broken with symmetry conservation, the reaction is symmetry-allowed. When the system is one lacking any molecular symmetry, the signs of the orbital lobes are determined by point-to-point transference from an analogous symmetrical system involving the same numbers of orbitals of the same types. We shall illustrate the procedure for all possible [2+2] reactions. In each case the four relevant electrons are first placed in pairs in the two generalized cyclobutane orbitals (136) and (137).

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  Organic Reaction Mechanisms 2015

  An annual survey covering the literature dated January to December 2015

  • A. C. Knipe(Author)
  • 2019(Publication Date)
  • Wiley

    (Publisher)

  CHAPTER 11 Addition Reactions: Cycloaddition N. Dennis 3 Camphor Laurel Crt, Stretton, Queensland, Australia 2 + 2-Cycloaddition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519 2 + 3-Cycloaddition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523 2 + 4-Cycloaddition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540 Miscellaneous Cycloadditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562 A review of advances in Nickel-catalysed Cycloaddition reactions directed towards the synthesis of carbocycles and heterocycles has been presented. The discussion includes the development and mechanistic studies of the Ni/NHC catalysts that couple diynes and nitriles to form pyridines. The use of vinyl cyclopropanes, aldehydes, ketones, tropones, 3-azetidinones, and 3-oxetenones as substrates in new Ni-catalysed Cycloaddition reactions is also discussed. 1 A second extensive review concerning Ni-catalysed Cycloaddition reactions that have been studied since 2004 has been published. 1,3-Dipolar Cycloadditions, Diels–Alder Cycloadditions, 2 + 2 + 2- Cycloadditions, and 3 + 3-Cycloadditions are discussed in this review. 2 The microwave irradiation of 4-(dimethylamino)-2H-chromen-2-one (1) with dimethyl acetylene dicarboxylate (DMAD) yielded dimethyl 1-(dimethylamino)naphthalene-2,3- dicarboxylate (2) as the product of a 2 + 2-Cycloaddition followed by 6-disrotatory electrocylization and elimination of CO 2 . The second product, 4-(dimethylamino) naphthalene-1,2-dicarboxylate (3), resulted from a 4 + 2-Cycloaddition followed by elimination of CO 2 (Scheme 1). 3 HelPhos-P-AuCl catalysts have been shown to be highly effective catalysts in the 2 + 2-, 4 + 2-Cycloadditions, and tandem cycliza- tion/addition reactions of allenenes and allene-dienes.

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  Organic Reaction Mechanisms 2019

  • Mark G. Moloney(Author)
  • 2023(Publication Date)
  • Wiley

    (Publisher)

  473 11 Addition Reactions: Cycloaddition N. Dennis 3 Camphorlaurel Crt, Stretton, Queensland, 4116 Australia CHAPTER MENU 2 + 2-Cycloaddition, 475 2 + 3-Cycloaddition, 477 2 + 4-Cycloaddition, 491 Miscellaneous Cycloadditions, 502 References, 513 An extensive review detailing the formal Cycloadditions of allenes and allenamides, catalysed by gold(I) and palladium(II) catalysts, has been presented. Formal [4 + 3]-, [4 + 2]-, [2 + 2]-, [2 + 3]-, [3 + 2]-, [2 + 1]-, [5 + 2]-, and [2 + 2 + 2]-annulations are discussed. 1 A detailed review of transition metal vinylidene- and allenylidene-mediated catalysis in organic synthesis includ- ing cyclopropanation and Cycloaddition has been presented. 2 A review of the 6-azaelectrocyclization of 1-, 2-, and 3-azatrienes and 1-azadienes in the total synthesis of natural products, bioactive heterocycles, and complex molecules is presented in detail. 3 The 2 + 1-Cycloaddition of oxa(aza)bicyclic alkenes/norbornene (1) in the presence of sodium azide (NaN 3 ) and arylsulfonyl chlorides afforded aziridine products (2, 3) in good yields (up to 82%). However, oxa(aza)bicyclic alkenes (1) with NaN 3 and chloroalkanes produced exo-1,2,3-triazolines (4) via a 3 + 2-Cycloaddition reaction in excellent yields (up to 95%) (Scheme 1). 4 The platinum-catalysed 3 + 2- and 2 + 2-Cycloadditions of allenes with alkene derivatives follow a stepwise process. Unsubstituted allenes and alkenes favour 3 + 2-Cycloaddition, while substituted allenes and unsubstituted alkenes favour 2 + 2-Cycloaddition. The selectivity between 3 + 2- and 2 + 2-Cycloadditions is controlled by the substituent on the allene moiety. 5 Tetrafluorothiophene-S,S-dioxide reacts with terminal alkynes to yield 2 + 2-cycloadducts and 4 + 2-Diels–Alder cycloadducts. The 2 + 2-cycloadducts are formed in a stepwise reac- tion via a singlet diradical intermediate. The [4 + 2]-adducts are produced in an asynchronous orbital symmetry allowed Diels–Alder reaction.

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  Science of Synthesis: Photocatalysis in Organic Synthesis

  • Burkhard König(Author)
  • 2019(Publication Date)
  • Thieme Chemistry

    (Publisher)

  16 Photocatalytic Cycloadditions A. G. Amador, S. O. Scholz, K. L. Skubi, and T. P. Yoon General Introduction PhotoCycloaddition reactions rank among the most important transformations available through photochemical activation. Like all Cycloaddition reactions, they can establish multiple new bonds and new stereocenters in a single operation, which makes them pow- erful tools for the rapid construction of molecular and stereochemical complexity. How- ever, the unique reactivity profile of electronically excited intermediates can lead to dis- tinctive product distributions, regioselectivities, and stereoselectivities that can differ dramatically from those of thermal Cycloadditions. Thus, photochemical activation al- lows direct access to complex molecular structures that are often not available through other approaches. The success of these processes is often dependent on the method of photochemical activation. For example, excited-state organic intermediates generated via direct UV irradiation often suffer from unproductive singlet-state deactivation path- ways such as fluorescence and E/Z isomerization that make these reactions relatively in- efficient. In some cases, it is possible to access similar product classes utilizing photocata- lytically generated radical ion, radical, and triplet excited-state intermediates. Classically, this approach exploited UV-activated organic photocatalysts such as benzophenone or an- thracene-9,10-dicarbonitrile. Recent methodologies, however, have made use of photoca- talysts that operate using visible irradiation. This chapter will highlight the most robust methodology in this area that makes use of visible-light-absorbing photocatalysts to pro- mote Cycloadditions, organized by the size of the ring formed. For a more comprehensive overview of modern photocatalysis, several general reviews have been recently pub- lished, [1,2] including applications in total synthesis.

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  Organic Reaction Mechanisms 2016

  An annual survey covering the literature dated January to December 2016

  • A. C. Knipe(Author)
  • 2019(Publication Date)
  • Wiley

    (Publisher)

  CHAPTER 11 Addition Reactions: Cycloaddition N. Dennis 3 Camphor Laurel Court, Stretton, Queensland, Australia 2 + 2-Cycloaddition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664 2 + 3-Cycloaddition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 666 2 + 4-Cycloaddition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 674 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 684 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 693 Tetrafluorothiophene S,S-dioxide is a potent cycloaddend that reacts as a Diels–Alder diene, a dienophile, and a 2 + 2-addend. Both Diels–Alder and 2 + 2-Cycloadditions can occur with terminal alkynes. 1 A tandem rhodium-catalysed C–H activation/intramolecular Diels–Alder reaction/ 1,3-dipolar Cycloaddition cascade process involving a diazole (1) and an eneyne (2) has yielded a decahydropyrene (3) with high stereoselectivity (Scheme 1). 2 Unsym- de  metrical aryl (mesityl) iodonium salts (4) are precursors of arynes for 1,3-dipolar and 4 + 2-Cycloaddition reactions with azides and furans, respectively. 3 Mechanistic studies on the Garratt–Braverman cyclization reactions have shown that for bis-propargyl ethers, an anionic 4 + 2-cyclization is involved. However, for bis-propargyl sulfones, a diradical mechanism is proposed. 4 The 2 + 2-Cycloaddition of N-alkyl imines with methanesulfonyl sulfene at 20 ∘ C yielded trans- -sultams in up to 69% yields. However, at low temperatures of −78 ∘ C, a 2 + 2 + 2-Cycloaddition with N-methyl imines produced 1,2,4-thiadiazine 1,1-dioxides (4-aza--sultams) in up to 80% yields. 5 de  The Pd(0)-catalysed intermolecular 2 + 2 + 1- and 2 + 2 + 2-carboCycloadditions of (1,n)-diynes (n = 6–9) with bromophenols provide an efficient route to tricyclic scaffolds possessing a quaternary carbon centre.

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  Lecture Notes On Fullerene Chemistry: A Handbook For Chemists

  A Handbook for Chemists

  • Roger Taylor(Author)
  • 1999(Publication Date)
  • ICP

    (Publisher)

  9 Cycloadditions Of all fullerene reactions, Cycloadditions have received by far the most study. This popularity stems from the ability to control the reaction so that only one addend becomes attached to the cage, making analysis of the produces relatively easy. The object of many of these syntheses is to produce intermediates for further reaction, though some of the functional groups do not undergo their normal reactions either readily or at all, when attached to fullerenes. This is due to both the strong electron withdrawal by the cage, and steric constraints. Six types of reaction are known: [1 + 2], [2 + 2], [3 + 2], [4 + 2], [6 + 2] and [8 + 2] Cycloadditions. The [4 + 2] group (Diels-Alder reactions) have been the subject of most attention. The number of compounds that have been made by Cycloaddition is already too vast to be described in detail here, consequently the reactions shown are selected either to be representative of general features, or have some aspect of special interest. There have been recent reviews on some of these reactions. 1-3 9.1 [1 + 2] Cycloadditions: Reactions That Produce Methano- and Homofullerenes and Their Heteroanalogues These additions involve either carbon, oxygen, nitrogen and silicon, numerous derivatives based upon these additions being now known. Addition of carbon has been the most studied to date, but addition of nitrogen (which leads to azafullerenes described in Chap. 13) and of oxygen (which can occur spontaneously) are rapidly gaining in importance. Two possible products are obtainable, arising from insertion into a 6,5 a-bond giving 9.1, or addition to a 137 9 Cycloadditions 9.1 [1 + 2] Cycloadditions: Reactions That Produce Methano- and Homofullerenes and Their Heteroanalogues 138 Lecture Notes on Fullerene Chemistry: A Handbook for Chemists 6,6 n-bond giving 9.2, the reason for these preferences having been given in Sec.

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  Organic Reaction Mechanisms 2014

  An annual survey covering the literature dated January to December 2014

  • A. C. Knipe(Author)
  • 2017(Publication Date)
  • Wiley

    (Publisher)

  141 The gold-catalysed formal (2 + 2 + 1)-Cycloaddition reaction of 1,6-diyne carbonates and esters with aldehydes formed 4-(cyclohexa-1,3-dienyl)-1,3- dioxolanes in good to excellent yields. An alkenylgold carbenoid (111) species is an important intermediate in this reaction. 142 The Ni(COD) 2 -catalysed (2 + 2 + 2)-Cycloaddition reaction of unsymmetrical diynes with CO 2 was investigated by DFT calculations. The regioselectivity of the catalytic reaction was elucidated during this investigation. 143 Again, the Ni(0)-catalysed inter- molecular (2 + 2 + 2)-Cycloaddition reaction of ethyl acrylate with norbornadiene N Pr i Pr i Pr i Pr i Au NCPh + SbF 6 – (111) O O O O R R (112) O O R R O O (113) Co(I) Scheme 37 11 Addition Reactions: Cycloaddition 607 (NBD) was investigated by DFT at the PBE level. The formation of the first C–C bond between the coordinated NBD and ethyl acrylate is the rate-determining step of the mechanism. 144 The Co(I)-catalysed intramolecular (2 + 2 + 2)-Cycloaddition reaction of yne-ene-yne diesters (112) produced highly strained pentacyclic bis-lactones (113), which can be transformed into tetraaryl N-hydroxyphthalimides (Scheme 37). 145 The intermolecular Rh-catalysed (2 + 2 + 2)-Cycloaddition reaction of benzothiophene dioxides with ,-diynes formed condensed polycyclic sulfone-containing cycloadducts in high yields. 146 The Ru(II)-catalysed intermolecular (2 + 2 + 2)-Cycloaddition reaction of o-alkenylarylacetylenes with terminal alkynes yielded dihydrobiphenylenes. Deuterium coupling experiments support a catalytic cycle mechanism. 147 The Rh-catalysed consecutive inter- and intra-molecular (2 + 2 + 2)-Cycloaddition reactions of thiophenylene-tethered triynes (114) yielded macrocyclic heteroarylenes as mixtures of dimers (115) and trimers (116) (Scheme 38). 148 The Nicholas reac- tion/(2 + 2 + 2)-Cycloaddition reactions were used to generate two new C 3 -symmetric hexasubstituted benzenes for molecular recognition studies.

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