Coupling Reactions
Coupling reactions in chemistry refer to the process of joining two molecular entities to form a new compound. This is typically achieved by the formation of a chemical bond between the two entities, often facilitated by a catalyst or reagent. Coupling reactions are widely used in organic synthesis to create complex molecules and are important in the production of pharmaceuticals, agrochemicals, and materials.
6 Key excerpts on "Coupling Reactions"
eBook - ePub- Greg T. Hermanson(Author)
- 2013(Publication Date)
- Academic Press(Publisher)
...Chapter 3 The Reactions of Bioconjugation Every chemical modification or conjugation process involves the reaction of one functional group with another, resulting in the formation of a covalent bond. The creation of bioconjugate reagents with spontaneously reactive or selectively reactive functional groups forms the basis for simple and reproducible crosslinking or tagging of target molecules. Of the hundreds of reagent systems described in the literature or offered commercially, most utilize common organic chemical principles that can be reduced down to a few dozen or so primary reactions. An understanding of these basic reactions can provide insight into the properties and use of bioconjugate reagents even before they are applied to problems in the laboratory. This section is designed to provide a general overview of activation and coupling chemistry. Some of the reagents discussed in this chapter are not themselves crosslinking or modification compounds, but may be used to form active intermediates with another functional group. These active intermediates can subsequently be coupled to a second molecule that possesses the correct chemical constituents, which allows bond formation to occur. Ultimately, this section is meant to function as a ready-reference database for learning or review of bioconjugate chemistry. In this regard, a reaction can quickly be found, a short discussion of its properties and use understood, and a visual representation of the chemistry of bond formation illustrated. What this section is not meant to be is an exhaustive discussion on the theory or mechanism behind each reaction, nor a review of every application in which each chemical reaction has been used...
eBook - ePub- Gopinathan Anilkumar, Salim Saranya(Authors)
- 2020(Publication Date)
- Wiley-VCH(Publisher)
...4 Cu-Catalyzed HomoCoupling Reactions Ganesh C. Nandi 1, Sundaresan Ravindra 1, Cholakkaparambil Irfana Jesin 1, Parameswaran Sasikumar 2, and Kokkuvayil V. Radhakrishnan 2,3 1 National Institute of Technology, Department of Chemistry, Tiruchirappalli 620015, Tamil Nadu, India 2 CSIR-National Institute for Interdisciplinary Science and Technology, Organic Chemistry Section, Chemical Sciences and Technology Division, Thiruvananthapuram 695019, Kerala, India 3 Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India 4.1 Introduction Transition metal-catalyzed C—C bond formations have been found to be a versatile tool in organic synthesis as they provide easy and cost-effective access to many pharmaceuticals and agrochemicals [ 1 ]. Being a 3d transition metal, copper (Cu) shows variable oxidation states (Cu(0), Cu(I), Cu(II), and Cu(III)), which efficiently catalyze reactions that follow both one- and two-electron pathways [ 2 ]. The foundation stone of copper-catalyzed Coupling Reactions was laid in 1869 [ 3 ], when Glaser synthesized diphenyldiacetylene via air oxidized dimerization of Cu(I)phenyl acetylide. The coordinating ability of Cu to pi-bond assists in activating terminal alkynes easily. Thereafter, Ullman developed the Cu-catalyzed synthesis of bi-aryl system from aryl halide in 1901 via a C–C coupling reaction [ 4 ]. In 1906, Goldberg used Cu for the synthesis of N-aryl compounds via C–N Coupling Reactions [ 5 ]. The successful organic transformations along with the economical and viable nature of the Cu-based catalysts were very attractive to the scientific community, and hence Cu-based catalysts demonstrated their efficiency in various types of C—C and C—X (X = heteroatom) Coupling Reactions [ 6 ]...
eBook - ePub- Victor Edwards, Suzanne Shelley(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
...7 Basic Concepts: Dynamics and Control of Chemical Reactions and Processes Chemical and Biomolecular Synthesis, Catalysis, and Reaction Engineering In Chapter 1, the definition of chemical engineering included the transformation of raw materials into useful products by changes in their physical and/or chemical characteristics. Biomolecular engineering plays an analogous role with biomolecules and biochemical transformations. In both disciplines, chemical and/or biochemical reactions are crucial to the creation of many products used by society. A chemical reaction is a process in which one or more chemical species, the reactants, are converted to one or more different chemical species, the products (Folger 1992). The identity of a chemical species is determined by the kind, number, and configuration of that species’ atoms (Folger 1992). A biochemical reaction is a chemical reaction that involves one or more different biochemical entities. Examples of biochemical entities are molecules such as antibiotics, sugars, and proteins. Enzymes, the catalytic agents of biochemical change in living organisms, and the living organisms themselves, may also be involved in biochemical reactions and may thus be biochemical entities. Chemical reactions between chemical species A and B to form chemical species C and D can be represented as follows: A + B = C + D 7.1 7.1 For an irreversible reaction (A and B react to form C and D, but almost no C and D react in the reverse reaction to form A and B), Equation 7.2 can represent the reaction rate (Solen and Harb 2012; Folger 1992; Harriott...
- Sunil S Joshi, Vivek V. Ranade(Authors)
- 2016(Publication Date)
- Elsevier(Publisher)
...Powerful coupling methodologies, such as Heck, Suzuki, Sonogashira, Negishi, Tsuji-Trost, and Buchwald-Hartwig coupling, enable synthetic organic chemists to accelerate total syntheses of APIs via carbon-carbon coupling. [ 34, 35, 36 ] Among the various name reactions in C–C coupling, Suzuki coupling has become the most practiced reaction in industry as evidenced by a recent literature search [ 37 – 41 ]. As shown in the scheme below, the choices of the ligand, metal, base, and solvent are important in determining the oxidative addition, transmetalation, and reductive elimination steps. Application in pharmaceutical industry 1. Synthesis of (+)-dicodermolide antifungal, immunosuppressive and cytotoxic [ 38 ]. 2. Synthesis of bis-indole alkaloid Dragmacidin D [ 39 ]. 3. Synthesis of diterpene (+)-phomactin A is a biologically active marine natural product [ 40 ]. 4. Synthesis of yuehhukene [ 41 ]. Heck coupling A Japanese scientist, Mizoroki (1971) and an American scientist, Heck (1972) independently developed a protocolto couple, an aryl or alkenyl halide or pseudohalide with an olefin in the presence of a Pd based catalyst [ 73, 74 ]. The application of this chemistry includes the synthesis of hydrocarbons, conducting polymers, light emitting electrodes, dyes, and enantioselective synthesis of natural...
eBook - ePub- J Fisher, J.R.P. Arnold, Julie Fisher, John Arnold(Authors)
- 2020(Publication Date)
- Taylor & Francis(Publisher)
...In some instances, it is necessary to activate the potential leaving group to make it a better leaving group and thus promote the substitution reaction. Substitution reactions are a feature of carboxylic acid chemistry and aromatic chemistry. Elimination reactions Elimination reactions occur with the loss of (generally) a small neutral molecule, from a larger molecule. These reactions are common with alkyl halides and alcohols, leading, in each case, to the formation of alkenes. Oxidation and reduction processes In organic systems oxidation and reduction reactions are those that involve the gain or loss of oxygen, respectively. Reduction reactions can also involve the gaining of hydrogen; equivalent to the loss of oxygen. In many instances these processes involve free radicals. Oxidation and reduction reactions are features of the chemistry of almost all organic compounds, and are of great significance in biology. Related topics (A1) The periodic table (A2) Electron confguration Addition reactions An addition reaction is said to have occurred when a molecule has combined with another, without the loss of any part (atom or groups of atoms) of either molecule. There are two general classes of addition reaction that may be considered, nucleophilic and electrophilic addition (Section I1). For either type of addition reaction to occur one or more units of unsaturation must be present in the molecule being added to. Consequently, addition reactions are only possible with, for example, alkenes, alkynes, aldehydes, and ketones...
eBook - ePub- Mukesh Doble, Anil Kumar Kruthiventi, Vilas Ganjanan Gaikar, Mukesh Doble, Anil Kumar Kruthiventi, Vilas Ganjanan Gaikar(Authors)
- 2004(Publication Date)
- CRC Press(Publisher)
...To add value is to profit. So, from the beginning, transformation was essential, whether in the making of metals and alloys, in medicinal preparations, in cooking, in dyeing and coloring, in tanning leather, or in the cosmetics. Reaction is fundamentally bringing about transformation. A directed reaction, which is a specific controlled reaction, can also be termed molecular engineering. Today, when a chemist thinks of a “reaction,” he or she sees both the macroscopic transformation as of old and the microscopic molecular change. Now we know, that in any chemical reaction the motions of the electrons and nuclei of atoms determine how the molecules interact and those interactions in turn create the forces that govern the reaction dynamics. 2.2.1 Basic Types of Reactions in Organic Chemistry At the molecular level a reaction starts when two molecules come close enough—within the bonding distance, approximately 0.1 nm—then they begin to interact. The electrons get rearranged; they start moving from an electron-rich center to an electron-deficient center. Transitory states are produced which either gets converted to the products or back to the reactants. These transitory states can be a transition state or an intermediate. Ahmed Zewail, a scientist from Caltech in the United States received the Nobel prize in chemistry (1999) for developing femtosecond laser photography to photograph these transitory states. The time scales for these transition states range from about 10 to 100 fs. A femtosecond is a very small unit of time. A femtosecond is to a second what a second is to 32 million years. Furthermore, while in 1 s light travels nearly 300,000 km—almost the distance between the earth and moon—in 1 fs light travels only 0.3 ìm—about the diameter of a smallest bacterium. When the movement/rearrangement of these electrons and nuclei is within the same molecule, it is termed an intramolecular reaction—similar to clasping of both the hands...
