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Chapter 1. Copper-Catalyzed Asymmetric Addition of Olefin-Derived Nucleophiles to Ketones A copper (I) catalyzed coupling olefins and ketones has been developed for the diastereo- and enantioselective generation of homopropargyl alcohols bearing vicinal stereocenters. This method allows for the generation of enantioenriched tertiary alcohols with a high degree of functional group compatibility. The utility of the process is further illustrated by a large scale synthesis with extremely low catalyst loading as well as the late stage modification of several pharmaceuticals. Chapter 2. Copper-Catalyzed Enantioselective Addition of Styrene-Derived Nucleophiles to Imines We describe the catalytic generation of amines bearing vicinal stereocenters with a moderate degree of diastereoselectivity. The stereoselective hydrocupration of an unactivated olefinic component is followed by nucleophilic addition of the organocuprate to an N-phosphinoyl protected imine. The mild and general process tolerates a broad-range of functionality, and the process was shown to be successful at a gram-scale synthesis. Chapter 3. Palladium-facilitated Regioselective Nucleophilic Fluorination of Aryl and Heteroaryl Halides. The preliminary findings regarding an aryl and heteroaryl halide fluorination process facilitated by palladium as a reagent is described. Stoichiometric studies illustrate the utility of the method in producing aryl fluorides with unprecedented regioselectivity, and preliminary studies into the fluorination of five- and six-membered heteroaryl bromides are described. Halogen atom substitution as a route to irreversible oxidative addition of aryl and heteroaryl halides is discussed. This strategy may serve to facilitate the fluorination of particularly problematic heteroaryl bromide and chloride substrates.
The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students
Chapter 1. Palladium-Catalyzed Fluorination of Cyclic Vinyl Triflates: Dramatic Effect of TESCF3 as an Additive A method for the synthesis of cyclic vinyl fluorides with high levels of regiochemical fidelity has been achieved by Pd-catalysis employing a new biarylphosphine ligand and TESCF3 as a crucial additive. Five, six, and seven-membered vinyl triflate substrates, as well as a few acyclic substrates undergo the transformation successfully. The intriguing "TESCF3 effect" provided a new tool for addressing the problem of the formation of regioisomers in Pd-catalyzed fluorination reactions. Chapter 2. Mechanistic Studies on Pd-Catalyzed Fluorination of Cyclic Vinyl Triflates: Evidence for in situ Ligand Modification by TESC3 as an additive. A detailed mechanistic hypothesis for the Pd-catalyzed fluorination of cyclic vinyl triflates, and the unusual effect of TESCF3 as an additive has been developed by combined experimental and computational studies. The preference of conducting [beta]-hydrogen elimination rather than reductive elimination from the trans-LPd(vinyl)F complex, which is generated predominantly due to the trans-effect, caused the poor regioselectivity of the fluorination reaction under TESCF3-free conditions. An in situ ligand modification by trifluoromethyl anion, leading to the generation of the cis-LPd(vinyl)F complex which prefers reductive elimination rather than Phydrogen elimination, is proposed to be responsible for the improved regioselectivity of the fluorination reaction when TESCF3 was used as an additive. Chapter 3. CuH-Catalyzed Enantioselective Alkylation of Indoles with Ligand-Controlled Regiodivergence A method for the enantioselective synthesis of either NI- and C3-chiral indoles by CuH-catalysis, depending on the choice of ligand, was developed. In contrast to conventional indole functionalization in which indoles are used as nucleophiles, hydroxyindole derivatives are employed as electrophiles in this method. DFT calculations indicated that the extent to which the Cu-P bonds of the alkylcopper intermediate distort, determines the regioselectivity of the reaction.
In 1912, the Chemistry Nobel Prize was awarded for the discovery of the so-called Grignard reagents. Nowadays, many transition metal variants are developed to modify reactivity and selectivity of the C–C bond formation reaction. The Grignard reaction is one of the fundamental organometallic reactions, often used in alcohol syntheses. With transition metals like iron, cobalt and nickel or with noble metals like copper, silver and palladium, modern Grignard reagents can be designed in reactivity, selectivity and functional group tolerance. This book, written by international experts, presents an overview on timely Grignard chemistry involving transition metals.
Late-Stage Fluorination of Bioactive Molecules and Biologically-Relevant Substrates reviews how the use of these techniques on compounds with already known and relevant biological activity can provide new pharmaceutical leads with improved medicinal properties. The fluorination strategies discussed take into account both conventional and novel reagents, including nucleophilic, electrophilic, those of a radical nature, and diverse families of organic compounds, such as (hetero) aromatic rings and aliphatic substrates. Drawing on the authors' expert knowledge, this book provides researchers with a broad set of applicable methods to use in their work.
"Transition-metal-catalyzed reactions have revolutionized the field of organic chemistry, enabling for the efficient synthesis of biologically and pharmaceutically relevant molecules. To this extent, this dissertation will focus on the development of new catalytic methods for the synthesis of organic molecules. Chapter 2 reports on the multimetallic Ni- and Pd- cross-electrophile coupling of vinyl bromides with vinyl triflates to form highly substituted 1,3-dienes. These dienes were subjected to Diels-Alder reactions and mechanistic experiments were performed to elucidate the reaction mechanism. Chapter 3 discusses the [Co(TPP)]-catalyzed (TPP = tetraphenylporphyrin) formation of substituted piperidines. Optimization studies, substrate screening, and mechanistic investigations will be discussed. Chapter 4 elaborates on how substitution on a variety of simple ketones and esters affects selectivity for C-H bond activation by tris-(3,5-dimethylpyrazolyl)borate rhodium complex. Lastly, Chapter 5 discusses the synthesis of novel bis((4,5-dihydrooxazol-2-yl)methyl)amine (ambox) ligated cobalt complexes. Importantly, this work provides the first insight into functionalization reactions of ambox-ligated cobalt complexes. Furthermore, these complexes are active towards hydrosilylation, hydroboration, C-C bond formation, and hydrogenation reactions alluding to the potential of this new class of cobalt-complexes for homogenous catalysis"--Page x.
Contents: Kilian Muñiz: Transition Metal Catalyzed Electrophilic Halogenation of C-H bonds in alpha-Position to Carbonyl Groups; Arkadi Vigalok * and Ariela W Kaspi: Late Transition Metal-Mediated Formation of Carbon-Halogen Bonds; Paul Bichler and Jennifer A. Love*: Organometallic Approaches to Carbon-Sulfur Bond Formation; David S. Glueck: Recent Advances in Metal-Catalyzed C-P Bond Formation; Andrei N. Vedernikov: C-O Reductive Elimination from High Valent Pt and Pd Centers; Lukas Hintermann: Recent Developments in Metal-Catalyzed Additions of Oxygen Nucleophiles to Alkenes and Alkynes; Moris S. Eisen: Catalytic C-N, C-O and C-S bond formation promoted by organoactinide complexes.
The first handbook on this emerging field provides a comprehensive overview of transition metal-catalyzed coupling reactions in the presence of an oxidant. Following an introduction to the general concept and mechanism of this reaction class, the team of authors presents chapters on C-C cross-coupling reactions using organometallic partners, C-Heteroatom bond forming reactions via oxidative couplings, and C-H couplings via C-H activation. The text also covers such groundbreaking topics as recent achievements in the fields of C-C and C-X bond formation reactions as well as C-H activation involving oxidative couplings. With its novel and concise approach towards important building blocks in organic chemistry and its focus on synthetic applications, this handbook is of great interest to all synthetic chemists in academia and industry alike.
This dissertation, "Density Functional Theory Studies of Selected Transition Metals Catalyzed C-C and C-N Bond Formation Reactions" by Xufeng, Lin, 林旭鋒, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled DENSITY FUNCTIONAL THEORY STUDIES OF SELECTED TRANSITION METALS CATALYZED C-C AND C-N BOND FORMATION REACTIONS submitted by Xufeng LIN for the degree of Doctor of Philosophy at The University of Hong Kong in September 2007 This thesis presents theoretical investigations on selected transition metals catalyzed C-C and C-N bond formation reactions. Density functional theory (DFT) calculations were performed to explore the potential energy surfaces of (1) alkyl-alkyl cross-coupling reactions catalyzed by nickel-trinitrogen ligand complexes, and (2) amidation of C-H bonds and alkene aziridinations catalyzed by rhodium and ruthenium complexes. In the first part three catalytic cycles were examined for Ni-catalyzed Negishi alkyl-alkyl cross-coupling with the ligand of 2,2'',6'',2''''-terpyridine (tpy). The catalytic cycle that involves a sequence of oxidative addition-reductive elimination- transmetalation with the actual catalyst of Ni(tpy)-CH or Ni(tpy)-I [Ni(I)] was found to be feasible, and this provide some new insight into the chemistry of metal-catalyzed cross-coupling reactions. The oxidative addition undergoes in a two-step radical pathway to produce a Ni(III) species, and the Ni(III) speices undergo reductive elimination to afford the alkyl-alkyl coupled product. Bulk solvation effect was considered in examination of this catalytic cycle. Cross-coupling reactions of both primary and secondary alkyl iodides in reactions with organozinc reagent were compared. Based on these results a Ni-catalyzed Negishi cross-coupling reaction of a secondary alkyl bromide was investigated with the ligands of bis(oxazolinyl)pyridine (Pybox). Reductive elimination step was found to be irreversible and rate-determining in generating the coupled product. When Pybox is replaced (S)-(i-Pr)-Pybox with C symmetry, it was found that the racemic 1-bromoindane can be converted into the coupled product in S enantiomer with high enantioselectivity. This is accounted for higher free energy of activation needed for the reductive elimination step in generating the R enantiomer compared to the S enatiomer in the case of (S)-(i-Pr)-Pybox ligand. In the second part the intramolecular amidation of C-H bonds in carbamates and sulfonamate esters were examined with dirhodium tetracarboxylate [Rh(II)] as the catalyst. "Rh(II)-nitrene" complexes were found to be largely favorable in free energy compared to the staring materials or the "Rh(II)-phenyliodinane" complexes. The singlet and triplet states of a Rh(II)-nitrene complex are very close in energy, which was attributed to the π-π orbital interaction of nitrene and Rh. However, a singlet Rh(II)- nitrene undergoes C-H bond cleavage accompanied by N-H and C-N bond formation in a concerted pathway, whereas a triplet Rh(II)-nitrene undergoes C-H bond cleavage accompanied by only N-H formation to produce a biradical. A singlet pathway is favorable over its corresponding triplet pathway in free energy of activation. Rh(II)- catalyzed nitrene insertion into a C=C double bond in competition with insertion into a C-H bond was also examined with the unsaturated substrate of sulfonamate esters. Similar cases were found for the reaction systems in which intramolecular amidation of C-H bonds in the cyclohexane ring in a sulfamate ester is catalyzed by Ru-porphyrins. In all these catalytic systems, stereoselectiviti