Issues in Chemistry and General Chemical Research: 2012 Edition

Issues in Chemistry and General Chemical Research: 2012 Edition
Author:
Publisher: ScholarlyEditions
Total Pages: 1539
Release: 2013-01-10
Genre: Science
ISBN: 1481645269

Issues in Chemistry and General Chemical Research: 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Chirality. The editors have built Issues in Chemistry and General Chemical Research: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Chirality in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Chemistry and General Chemical Research: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Organozinc Derivatives and Transition Metal Catalysts

Organozinc Derivatives and Transition Metal Catalysts
Author: Janine Cossy
Publisher: Walter de Gruyter GmbH & Co KG
Total Pages: 222
Release: 2023-05-22
Genre: Science
ISBN: 3110728850

Organozinc reagents are less reactive than Grignard reagents but they are much more chemoselective. Since the Negishi cross-coupling reaction developed by Ei-ichi Negishi, who was awarded the Nobel Price in chemistry in 2010, a number of cross-coupling reactions involving organozinc derivatives and transition metal catalysts (Pd, Ni, Fe, Co, Cu, ...) has been tuned up to form C-C bonds. This book on "Organozinc derivatives and transition metal catalysts" has been written by experts in the field and is a complement to the book entitled "Grignard reagents and transition metal catalysts" (a De Gruyter book, edited by J. Cossy). Grignard reagents or organozinc reagents, that is the question? From a given substrate, what is the best organometallic reagent and the best transition metal to form a C-C bond by using a cross-coupling reaction? The solution might be found in these two books.

Chromium Complexes of Amine-bis(phenolate) Ligands as Copolymerization Catalysts

Chromium Complexes of Amine-bis(phenolate) Ligands as Copolymerization Catalysts
Author: Hua Chen
Publisher:
Total Pages:
Release: 2014
Genre:
ISBN:

Alternating copolymerization of CO2 with epoxides to provide polycarbonates is a promising reaction for the industrial production of biodegradable thermoplastics, which have been widely used in electronics, optical media, the automotive industry, the medical and healthcare industry, and many consumer goods. Homogeneous catalysts containing transition metals including Co, Cr and Zn have been active for this reaction. Previous work in the group involved using amine-bis(phenolates) with different metals to generate catalysts and reactive species for use in several reactions. It was found that Cr complexes of tetradentate amine-bis(phenolate) ligands were promising catalysts for the copolymerization of CO2 with cyclohexene oxide (CHO) and propylene oxide (PO). This thesis seeks to further that research by investigating different amine-bis(phenolates) to study their structure-polymerization activity relationship. The ligands used in this thesis were tridentate or tetradentate amine-bis(phenolates) where the substituents on the phenolate groups and pendant arm were varied. Three ligands used were 2-tetrahydrofurfuryl-N,N-bis(2-methylene-4,6-tert-butylphenol), H2[L1], benzylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2[L2], and benzylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H2[L3]. The synthesis and characterization of related lithium complexes 1, 2 and 3 and also chromiumIII complexes 4, 5 and 6 were performed. Three chromium complexes were isolated and characterized by UV-Vis spectroscopy, mass spectrometry, elemental analysis and, for complex 5, single-crystal X-ray diffraction. The copolymerization of cyclohexene oxide with CO2 to yield polycarbonates was investigated with these chromiumIII amine-bis(phenolate) complexes. The resulting polymers were analyzed by 1H and 13C NMR spectroscopy, MALDI-TOF mass spectrometry and gel permeation chromatography.

Enantioselective C-C Bond Forming Reactions

Enantioselective C-C Bond Forming Reactions
Author:
Publisher: Elsevier
Total Pages: 338
Release: 2023-12-01
Genre: Science
ISBN: 044323700X

Enantioselective C-C Bond Forming Reactions: From Metal Complex-, Organo-, and Bio-catalyzed Perspectives, Volume 73 in the Advances in Catalysis series, highlights new advances in the field, with this new volume presenting interesting chapters on topics such as An introduction to Chirality, Metal-catalyzed stereoselective C-C-bond forming reactions, Enantioselective C-C bond forming reactions promoted by organocatalysts based on unnatural amino acid derivatives, Enantioselective C-C bond formation in complex multicatalytic system, Gold-based multicatalytic systems for enantioselective C-C Bond forming reactions, Novel enzymatic tools for C-C bond formation through the development of new-to-nature biocatalysis, and more. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in Advances in Catalysis serials Updated release includes the latest information in the field

Applied Cross-Coupling Reactions

Applied Cross-Coupling Reactions
Author: Yasushi Nishihara
Publisher: Springer Science & Business Media
Total Pages: 247
Release: 2012-12-14
Genre: Science
ISBN: 3642323685

“Applied Cross-Coupling Reactions” provides students and teachers of advanced organic chemistry with an overview of the history, mechanisms and applications of cross-coupling reactions. Since the discovery of the transition-metal-catalyzed cross-coupling reactions in 1972, numerous synthetic uses and industrial applications have been developed. The mechanistic studies of the cross-coupling reactions have disclosed that three fundamental reactions: oxidative addition, transmetalation, and reductive elimination, are involved in a catalytic cycle. Cross-coupling reactions have allowed us to produce a variety of compounds for industrial purposes, such as natural products, pharmaceuticals, liquid crystals and conjugate polymers for use in electronic devices. Indeed, the Nobel Prize for Chemistry in 2010 was awarded for work on cross-coupling reactions. In this book, the recent trends in cross-coupling reactions are also introduced from the point of view of synthesis design and catalytic activities of transition-metal catalysts.

Pd Catalysed C-C & C-O Bond Formation Using Bis-(dialkyl/diarylphosphino)ferrocene Ligands

Pd Catalysed C-C & C-O Bond Formation Using Bis-(dialkyl/diarylphosphino)ferrocene Ligands
Author: Edward J. Milton
Publisher:
Total Pages:
Release: 2010
Genre:
ISBN:

A brief introduction explaining phosphine ligand properties, Pd catalysed cross-coupling reactions; the importance of the steps involved in the catalytic cycle (oxidative addition, transmetalation & reductive elimination), mechanistic studies and a comparison of various reactions will give an overview of important cross-coupling reactions and their limitations. The development of a "super-concentrated" (5M) Pd catalysed Kumada type coupling reaction has been developed for coupling a range of aryl bromide and chloride substrates with the Grignard reagents ((p-CF3-C6H4)MgBr)) and PhMgBr in methyl-tetrahydrofuran (Me-THF). Using a range of bidentate ligands such as bis-phosphinoferrocenyl ligands, good conversions were achieved using small amounts of solvent; up to 10 times less than typical procedures in THF. The unsymmetrical Pt complexes of the form [Pt(P-P)Br2], [Pt(P-P)(Ph)Br] and [Pt(P-P)Ph2] have been synthesised and characterised. The variations of substituents on the ligand system and the steric bulk have been shown to have a dramatic effect on the rate of transmetalation. The results provide one explanation why 1,1'-bis(di tert-butylphosphino)ferrocene (dtbpf), an excellent ligand for certain Suzuki reactions, is quite poor in reactions where transmetalation is more difficult. Palladium dichloride complexes of the ferrocenylphosphine based ligands 1,1'-bis- (diphenylphosphino)ferrocene (dppf), 1,1'-bis-(diisopropylphosphino)ferrocene (dippf) and 1,1'-bis-(di-tert-butylphosphino)ferrocene (dtbpf) have been shown to be active in the Hiyama cross-coupling of p-bromoacetophenone and vinyltrimethoxysilane (CHCH2Si(OMe3)) in the presence of TBAF under thermal heating and microwave conditions. Ligands with the optimum balance for promoting the transmetalation, oxidative addition and reductive elimination steps along the reaction pathway have been identified. Competition experiments are consistent with slow transmetalation being an issue with the Hiyama reaction relative to the Suzuki coupling. A novel protocol has been developed for the synthesis of aryl-alkyl ethers via C-O bond activation under Pd catalysed conditions. Utilising the unsymmetrical 1-bis-(ditertbutyl-1'- bis-diphenylphosphino)ferrocene (dtbdppf) under optimised conditions with silicon based nucleophiles and NaOH or TBAF as an activator, the formation of methyl, ethyl, n-propyl and n-butyl ethers with a range of aryl halides was achieved in good yield.