Phosphorus-carbon Bond Formation PDF Download

Author: Sylvine Deprele
Publisher:
ISBN:
Category : Chemical bonds
Languages : en
Pages : 474

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Author: Robert Engel
Publisher: CRC Press
ISBN: 0203998243
Category : Science
Languages : en
Pages : 200

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Book Description
Synthesis of Carbon-Phosphorus Bonds, Second Edition is a working guide for the laboratory, incorporating classical approaches with the recent developments of carbon-phosphorus (C-P) bond formation. These advances include the preparation of phosphoranes - specifically in the use of transient oxophosphoranes as intermediates in organophosphorus comp

Author: Michael B. Geeson
Publisher:
ISBN:
Category :
Languages : en
Pages : 373

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Chapter 1 takes the format of an "Outlook", and sets forth the case for developing sustainable methods in the synthesis of phosphorus-containing compounds. Methods used by nature for phosphorus-carbon bond-formation, or in the chemistry of other elements such as silicon, are discussed as model processes for the future of phosphorus in chemical synthesis. Chapter 2 describes the discovery of [TBA][P(SiCl3)2], prepared from [TBA]3[P3O9]-.2H2O and trichlorosilane. The bis(trichlorosilyl)phosphide anion is used to prepare compounds that contain P–C, P–O, P–F, and P–H bonds in a method that bypasses white phosphorus (P4), the traditional route to organophosphorus compounds. Chapter 3 extends the phosphate precursors to [TBA][P(SiCl3)2] from trimetaphosphate to crystalline phosphoric acid. Balanced equations are developed for the formation of [TBA][P(SiCl3)2] from phosphate sources and the byproducts are identified as hexachlorodisiloxane and hydrogen gas. Extension of trichlorosilane reduction to bisulfate provides improved access the known trichlorosilylsulfide anion, [TBA][SSiCl3]. This anion was used as a thionation reagent to prepare thiobenzophenone and benzyl mercaptan from benzophenone and benzyl bromide, respectively. Chapter 4 describes the synthesis of neutral phosphine, HP(SiCl3)2, obtained by protonation of [TBA]1 with triflic acid. HP(SiCl3)2 is a highly efficient reagent for photochemical hydrophosphination of terminal alkenes. The phosphorus-silicon bonds in the hydrophosphination products can be functionalized to provide compounds of the general formulae: RPCl2, RPH2, [RP(R')3]Cl, RP(O)(H)(OH), and RP(O)(OH)2. Chapter 5 describes a method to prepare phosphiranes (three-membered rings that contain a phosphorus atom) from anthracene-based phosphinidene precursors and styrenic olefins. The phosphinidene transfer reaction requires an organoiron and fluoride catalyst. The resulting phosphirane is prepared in good yield (73%) with high stereoselectivity (>99%). Experimental investigations into the mechanism point toward the intermediacy of an iron-coordinated fluorophosphide species.

Author: Yamina Belabassi
Publisher:
ISBN:
Category : Chemical bonds
Languages : en
Pages :

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The work presented in this dissertation deals with the development of new methodologies for P-C bond formation as well as synthesizing biologically relevant organophosphorus compounds. A distinct emphasis is given to the important synthetic targets, the H-phosphinates. A review of relevant literature is provided in Chapter 1. Chapter 2 describes the synthesis and structural analyses, of triphenylmethyl-containing phosphorus compounds. For the first time, both phosphonothioic and boranophosphonic acids have been characterized by single X-ray diffractometry. The third chapter details the preparation and the reactivity of phosphine-borane complexes. Novel dialkoxyphosphine-borane complexes were introduced, both as general synthetic intermediates for the preparation of H-phosphinates or disubstituted phosphinic acids, and as boranophosphonate precursors. Related to this chemistry, silylation of an H-phosphinate intermediate can also be conducted and the resulting phosphonite protected with borane. This allows the temporary protection of the sensitive P-H group, so that manipulations of the alkyl chain might be conducted. In chapter 4, the palladium-catalyzed cross-coupling reaction of dialkylphosphites with aryl and heteroaryl halides is presented. An efficient, versatile and economically attractive alternative to the original Hirao cross-coupling by using only 1 mol% (or less) Pd(OAc)2/dppf is described. Moreover, first example of palladium-catalyzed P-C bond formation between activated aryl chlorides and a phosphite are herein reported. Chapter 5 focuses on the free-radical hydrophosphinylation of alkynes. The triethylborane-initiated radical addition of sodium hypophosphite to terminal alkyne affords the previously unknown 1,1-bis-H-phosphinates, precursors of the biologically relevant 1,1-bisphosphonates (e.g., treatment of bone diseases). Thus, the oxidative conversion of 1,1-bis-H-phosphinates to the corresponding bisphosphonates, as well as the synthesis of a series of bio-conjugates (steroids, carbohydrates, fluoroquinolones) was investigated. In the last chapter, the palladium-catalyzed hydrophosphinylation of hypophosphorous acid derivatives to terminal alkynes is reported. In an effort to improve the regioselectivity of the reaction, various terminal alkynes were tested, as well as the solvent and catalyst system.

Author: Henry C. Fisher
Publisher:
ISBN:
Category : Chemical bonds
Languages : en
Pages :

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The work in this dissertation deals with the continued development of new methodologies for P-C and P-O bond formation using alternative methods that avoid the use of PCl3. A review of the relevant literature that proceeds this work is presented in Chapter 1. Chapter 2 describes the study of the P(III) to P(V) tautomerization of phosphinylidene compounds and the structural influences that effect the thermodynamic and kinetic properties to favor the more reactive P(III) species. A collaboration using both computational and experimental methods, show that electron withdrawing groups such as phenyl stabilize the tautomerization of phosphinylidene compounds. The second part of this work highlights the influence of various catalysts on P(III) to P(V) tautomerization. Using computational chemistry as a screening tool, a variety of organic acids and bases were tested. The calculations and experimental results are in good agreement. Chapter 3 describes the work to develop the nickel-catalzyed hydrophosphinylation of unactivated alkenes, an extension of the work started with the nickel-catalyzed hydrophosphosphinylation of alkynes. The results show that nickel chloride is pre-activated to an active Ni(0) species and can be stabilized by the inexpensive bisphosphine ligand, ethylbis(diphenylphosphine), dppe. The reaction occurs at room temperature and works on a variety of different alkene substrates. Other manipulations used in tandem with the initial nickel hydrophosphinylation are highlighted, and show the reaction to be a versatile tool for making alkyl-H-phosphinate derivatives as precursors for further use. Chapter 4 details the development of manganese-promoted intermolecular and intramolecular additions of alkenes, alkynes and aryl compounds with H-phosphinates is described. The system utilizing catalytic Mn(OAc)2 either neat or in DMSO, is successful for a variety of different alkenes and two alkyne substrates. A more efficient and cost-effective system was recently developed for H-phosphinate arylations using catalytic Mn(OAc)2 and MnO2 as an oxidant, and further applied to alkene phosphonochlorination with LiCl. In Chapter 5, nickel-catalyzed oxidation of alkyl hypophosphites is utilized to prepare ubiquitous alkyl-H-phosphonates starting from hypophosphorous acid and avoiding the use of PCl3. The reaction can be considered a form of water splitting. The studies show that after the intitial esterification step, NiCl2 or Ni/SiO2 is enough to oxidize the first P-H bond to form the desired phosphonate. The reaction has been applied to the synthesis of the global herbicide glyphosate.

Author: Robert Engel
Publisher: CRC Press
ISBN: 9781135502034
Category : Science
Languages : en
Pages : 200

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Book Description
Synthesis of Carbon-Phosphorus Bonds, Second Edition is a working guide for the laboratory, incorporating classical approaches with the recent developments of carbon-phosphorus (C-P) bond formation. These advances include the preparation of phosphoranes - specifically in the use of transient oxophosphoranes as intermediates in organophosphorus compound synthesis ñ along with the new approaches towards the preparation of compounds with aromatic and vinylic C-P bonds. Synthesis of Carbon-Phosphorus Bonds, Second Edition serves as a useful tool in the laboratory. It offers detailed surveys of IUPAC nomenclature recommendations, common notation systems, and various experimental examples. These features help to make this text an effective source of critical and annotated references, as well as a a working guide for organic and phosphorus chemists specifically, or for any chemists working with C-P bonds.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The focus of this work lies on the exploitation of hypophosphorous derivatives in order to develop new methodologies for P-C bond formation as well as synthesizing biologically relevant phosphorus compounds. A review of the work published to date from the Montchamp group is provided in Chapter 1: Much of the methodology is applied in the remainder of the thesis in reactions such as radical addition, base-promoted alkylation and cross-coupling of anilinium hypophosphite. The following chapter describes initial results of the transition-metal catalyzed cross-coupling in the presence of beta-hydrogens and with chloromethylphthalimide. The application of phosphine-borane chemistry as a phosphinylidene protecting group is discussed in Chapter 3. An in-depth literature review provides the background for the new methodology. Novel gamma-aminobutyric acid analogues are synthesized using methods developed within the Montchamp group. Their synthesis and biological evaluation are discussed in the final chapter.

Author: Arumugam Jayaraman
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Chloride abstraction reactions have been investigated towards the formation of metal-coordinated phosphenium ions ([M]-PR2+) from metal-coordinated chlorophosphines. The electron-poor metal fragment W(CO)5 was used on all studied chlorophosphine complexes. Chlorophosphines [W(CO)5{P(Cl)C(Ph)C(Ph)}] (4), [W(CO)5{PPh2Cl}] (32), [W(CO)5{PPhCl2}] (60), [W(CO)5{PCl3}] (100) and [W(CO)5{P(NEt2)Cl2}] (101) were synthesized using existing or new methods. Chloride abstraction from 4 with excess AlCl3 leads to the phosphirenyl cation complex [W(CO)5{PC(Ph)C(Ph)}][AlCl4] (8). Compound 8 undergoes electrophilic aromatic substitution with ferrocene to form a ferrocenylphosphirene complex. Chloride abstraction from 4 with AgOSO2CF3 leads to a phosphirenyl triflate complex 12, which reacts with ferrocene in the same fashion as 8 but also reacts cleanly with a wider range of substrates, including phenylacetylene, allyltrimethylsilane, activated to moderately-activated benzene derivatives, and heteroaromatic compounds and formed P-C bond at the expected positions. Most of the substitution reactions are rapid at ambient temperature, regioselective, and the product yields were good to excellent. Chloride abstraction from 32 using AgOSO2CF3 led to the formation of diphenyl phosphine triflate complex 34. However, with AlCl3 an equilibrium mixture of the isocarbonyl complex [W(CO)4{COAlCl3}{PPh2Cl}] and phosphenium complex [W(CO)5{PPh2}][AlCl4] (33a) were formed. With GaCl3, only the phosphenium complex 33b was formed. Compounds 34 and 33a react in a similar fashion to phosphirenyl triflate complex 12 with various aromatic substrates, and showed an increased reactivity than 12. In addition to aromatic and heteroaromatic substrates, 34 and 33a react with alkenes, alkynes and ketones. With alkenes and alkynes, P-C bonded products were formed, but with ketones P-O bond formation is predominant. Reaction of 60 with AlCl3 resulted in the disappearance of 60 in the 31P{1H} NMR spectrum, but no detectable signal for the phosphenium ion complex. Addition of activated aromatic substrates to this solution leads to disubstitution. The AgOSO2CF3 selectively converts compound 60 to the mono-substituted phosphine-triflate complex [W(CO)5{PPhCl(OSO2CF3)}] (62), which reacts with various aromatic substrates, including less activated ones, to afford a variety of phenyl aryl chloro complexes. Most of the phenyl aryl chloro phosphine complexes were subsequently converted to corresponding triflates and reacted with ferrocene to show the possibility of sequential substitution of two chloride substituents with two different carbon-based substituents. Complex 100 was used to test the possibility of substituting all three Cl substituents of P with three different carbon-based-substituents, but chloride abstraction was not possible from this complex. Therefore, compound 101 was examined as an alternative. In the presence of AlCl3, it reacts successively with allyl trimethylsilane, indole and ferrocene to form the 3-indolyl allyl ferrocenyl phosphine complex in a single pot. Phosphine products can be removed via oxidation of W with I2, followed by displacement with bipyridine, or by photolysis of the THF solution containing phosphine complex and bis(diphenylphosphino)ethane. Density Functional Theory calculations were also performed to assess the relative electrophilicities of the studied phosphenium ion complexes.

Author: Trevor W. Tennis
Publisher:
ISBN:
Category : Organophosphorus compounds
Languages : en
Pages : 112

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Research has been focused on the design or discovery of processes for the formation of phosphorus-carbon bonds. Phosphonates in particular have generated a lot of interest due to their biological properties. Of the phosphonates, keto-phosphonates have received a lot of attention due to their srong antibacterial properties. The focus of my research is to develop a method for the formation of y-keto-phosphonates with high enantiomeric excesses.

Author: Louis D. Quin
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 456

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