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Author: Floriana Andreea Foarta
Publisher:
ISBN:
Category :
Languages : en
Pages : 458
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Book Description
Rhodium-catalyzed asymmetric hydroformylation is an atom efficient method to synthesize optically active aldehydes from simple alkenes, carbon monoxide and hydrogen. Such aldehydes serve as precursors to pharmaceuticals and fine chemicals. Efficient hydroformylation was demonstrated previously for many monosubstituted alkenes. Access to chiral aldehydes with more diverse branching substituents remains, however, limited. This work extends effective enantioselective hydroformylation to 1,2-disubstituted alkenes, particularly (Z)-enol esters and (Z)-enamides, and to 1,1'-disubstituted alkenes, predominantly alpha-substituted unsaturated esters. Functionalized aldehydes with tertiary and quaternary stereogenic centers are obtained with high stereo and regiocontrol at mild pressures in the presence of Rh-BisDiazaphos or Ph-BPE catalysts. The iterative application of the sequence Rh-BisDiazaphos catalyzed asymmetric hydroformylation of (Z)-enol esters / aldehyde oxidation / Ru catalyzed alkyne hydroacyloxylation enables catalytic, low-waste synthesis of sequence specific chiral oligoesters. This method demonstrates that short oligomers can be synthesized with sequence specificity and stereocontrol in the absence of coupling reagents and protecting groups.
Author: Floriana Andreea Foarta
Publisher:
ISBN:
Category :
Languages : en
Pages : 458
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Book Description
Rhodium-catalyzed asymmetric hydroformylation is an atom efficient method to synthesize optically active aldehydes from simple alkenes, carbon monoxide and hydrogen. Such aldehydes serve as precursors to pharmaceuticals and fine chemicals. Efficient hydroformylation was demonstrated previously for many monosubstituted alkenes. Access to chiral aldehydes with more diverse branching substituents remains, however, limited. This work extends effective enantioselective hydroformylation to 1,2-disubstituted alkenes, particularly (Z)-enol esters and (Z)-enamides, and to 1,1'-disubstituted alkenes, predominantly alpha-substituted unsaturated esters. Functionalized aldehydes with tertiary and quaternary stereogenic centers are obtained with high stereo and regiocontrol at mild pressures in the presence of Rh-BisDiazaphos or Ph-BPE catalysts. The iterative application of the sequence Rh-BisDiazaphos catalyzed asymmetric hydroformylation of (Z)-enol esters / aldehyde oxidation / Ru catalyzed alkyne hydroacyloxylation enables catalytic, low-waste synthesis of sequence specific chiral oligoesters. This method demonstrates that short oligomers can be synthesized with sequence specificity and stereocontrol in the absence of coupling reagents and protecting groups.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 580
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Book Description
Hydroformylation is a large-scale commodity process in the synthesis of aldehydes from alkene, carbon monoxide and hydrogen gas starting materials; in contrast, asymmetric hydroformylation (AHF) is underutilized in the synthesis of chiral aldehydes. Because rhodium-catalyzed hydroformylation exhibits perfect atom-economy, high turnover numbers, and fast rates, this is a desirable reaction in synthesis of branched chiral aldehydes. Challenges in AHF include control of selectivity (chemo-, regio-, and enantio-), slow rates of reaction, and a limited substrate scope. Currently, only a handful of chiral phosphorus-containing ligands exhibit state-of-the-art rates of reaction and high levels of enantioselectivity in rhodium-catalyzed hydroformylation for a broad range of substrates; even less of these have found applications in complex molecule and natural product synthesis. This work describes the synthesis of a bis-3,4-diazaphospholane ligand library, hydroformylation of O-functionalized alkenes, and application with Wittig olefination in the synthesis of complex organic molecules. A library of bis-3,4-diazaphospholanes ligands was generated by varying the steric bulk in the secondary coordination sphere and applied to the hydroformylation of three terminal alkenes. Styrene exhibited modest variations in regio- and enantioselectivity, whereas, vinyl acetate and allyloxy-t-butyldimethylsilane exhibited fairly minor changes. Enantioselective hydroformylation of allyl ethers with bisdiazaphospholane ligands yield synthetically useful building blocks for organic synthesis; one prominent example, chiral "Roche aldehyde" can be accessed from inexpensive allyl alcohol. AHF of 5-grams of an allyl silyl ether and a protected acrolein demonstrate scalable syntheses of chiral building blocks relevant for natural product synthesis. One-pot asymmetric hydroformylation-Wittig olefinations (AHF-WO) is performed with various alkenes using Rh-bisdiazaphospholane catalysts resulting in [alpha,beta]-unsaturated carbonyl products. In these experiments multiple AHF-WO iterations demonstrate the utility of the synthesis of complex molecules with various functionalities, multiple carbon-carbon double bonds, and stereocenters. Overall this body of work promotes the use of bisdiazaphospholane ligands for enantioselective hydroformylation and organic synthesis.
Author: Lisi He
Publisher: LAP Lambert Academic Publishing
ISBN: 9783846500514
Category : Alkenes
Languages : en
Pages : 88
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Book Description
Alkenes are important primary chemicals for supporting our daily life from domestic utilities to off-the-shelve drugs. Internal and monosubstituted alkenes preparation technologies are now practicing in modern industry at a large scale, however, further potentials may possibly bounded by the availability of low cost synthetic methodology to access new derivatives with better environmental issues awareness. This book begins with highlighting the key former distinguish achievements in the area of Ni-H chemistry with olefins, follows by providing rationale on how we come up a new idea that gives asymmetric terminal disubstituted olefins in a catalytic and greener way, how we overrides several key existing problems in the field and relieves the bottleneck situation between the chemical feedstocks and large varieties of value-adding olefin transformations. This book closes with detailing technical procedures for readers to pursue the chemistry easily. The presented conceptual advance and exciting development should be useful to R & D professionals in Petroleum Industry, Polymers and Fine Chemicals Companies or those who plan to use geminal olefins for subsequent synthetic applications.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 298
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Book Description
The conversion of olefins into aldehydes by hydroformylation with rhodium catalysts is one of the largest homogeneously catalyzed industrial reactions, producing millions of tons of linear aldehydes per year. However, the production of chiral, branched aldehydes via asymmetric hydroformylation (AHF) remains underutilized in synthesis. To improve the application of rhodium BisDiazaphos catalyzed AHF, high selectivity for previously uninvestigated disubstituted olefins including enol esters and enamides is demonstrated, which yield more complex [alpha]-functionalized aldehyde building blocks. Additionally, process-scale asymmetric hydroformylation to yield chiral, enantioenriched aldehyde feedstocks has not yet been demonstrated. In collaboration with Eli Lilly, asymmetric hydroformylation in a research scale flow reactor is realized through the development of a flow synthesis of naproxen. To support scale-up of asymmetric hydroformylation technologies the synthesis of bisdiazaphospholane ligands is re-examined to optimize the cost of the material and synthesis on a larger scale is demonstrated. Access to enantiopure ligand via classical resolution in place of preparative SFC chromatography has also been developed, and will improve accessibility to selective AHF catalysts. Finally, the direct observation of catalytic intermediates and rate information in asymmetric hydroformylation by circulating high-pressure NMR will be described.
Author: Xiao-Feng Wu
Publisher: John Wiley & Sons
ISBN: 3527348956
Category : Science
Languages : en
Pages : 1780
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Book Description
The Chemical Transformations of C1 Compounds A comprehensive exploration of one-carbon molecule transformations The chemistry of one-carbon molecules has recently gained significant prominence as the world transitions away from a petroleum-based economy to a more sustainable one. In The Chemical Transformations of C1 Compounds, an accomplished team of chemists delivers an in-depth overview of recent developments in the field of single-carbon chemistry. The three-volume book covers all major C1 sources, including carbon monoxide, carbon dioxide, methane, methanol, formic acid, formaldehyde, carbenes, C1 halides, and organometallics. The editors have included resources discussing the main reactions and transformations into feedstock chemicals of each of the major C1 compounds reviewed in dedicated chapters. Readers will discover cutting-edge material on organic transformations with MeNO2, DMF, DCM, methyl organometallic reagents, CCl4, CHCl3, and CHBr3, as well as recent achievements in cyanation reactions via cross-coupling. The book also offers: Thorough introductions to chemical transformations of CH4, methods of CH4 activation, chemical transformations of CH3OH and synthesis alkenes from CH3OH Comprehensive explorations of the carbonylation of MeOH, CH2O in organic synthesis, organic transformations of HCO2H, and hydrogen generation from HCO2H Practical discussions of the carbonylation of unsaturated bonds with heterogeneous and homogeneous catalysts, as well as the carbonylation of C(sp2)-X bonds and C(sp3)-X bonds In-depth examinations of carbonylative C-H bond activation and radical carbonylation Perfect for organic and catalytic chemists, The Chemical Transformations of C1 Compounds is also an ideal resource for industrial chemists, chemical engineers, and practitioners at energy supply companies.
Author: Mohammad Odeh Bani Khaled
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: David J. Cole-Hamilton
Publisher: Springer Science & Business Media
ISBN: 9781402040863
Category : Science
Languages : en
Pages : 270
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Book Description
This book looks at new ways of tackling the problem of separating reaction products from homogeneous catalytic solutions. The new processes involve low leaching supported catalysts, soluble supports such as polymers and dendrimers and unusual solvents such as water, fluorinated organics, ionic liquids and supercritical fluids. The advantages of the different possibilities are discussed alongside suggestions for further research that will be required for commercialisation. Unlike other books, in addition to the chemistry involved, the book looks at the process design that would be required to bring the new approaches to fruition. Comparisons are given with existing processes that have already been successfully applied and examples are given where these approaches are not suitable. The book includes: - New processes for the separation of products from solutions containing homogeneous catalysts - Catalysts on insoluble or soluble supports – fixed bed catalysts - continuous flow or ultrafiltration - Biphasic systems: water - organic, fluorous - organic, ionic liquid – organic, supercritical fluids (monophasic or biphasic with water, organic or ionic liquid) - Comparisons with current processes involving atmospheric or low temperature distillation - Consideration of Chemistry and Process Design - Advantages and disadvantages of each process exposed - Consideration of what else is need for commercialisation
Author: Piet W.N.M. van Leeuwen
Publisher: Springer Science & Business Media
ISBN: 0306469472
Category : Science
Languages : en
Pages : 291
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Book Description
In the last decade there have been numerous advances in the area of rhodium-catalyzed hydroformylation, such as highly selective catalysts of industrial importance, new insights into mechanisms of the reaction, very selective asymmetric catalysts, in situ characterization and application to organic synthesis. The views on hydroformylation which still prevail in the current textbooks have become obsolete in several respects. Therefore, it was felt timely to collect these advances in a book. The book contains a series of chapters discussing several rhodium systems arranged according to ligand type, including asymmetric ligands, a chapter on applications in organic chemistry, a chapter on modern processes and separations, and a chapter on catalyst preparation and laboratory techniques. This book concentrates on highlights, rather than a concise review mentioning all articles in just one line. The book aims at an audience of advanced students, experts in the field, and scientists from related fields. The didactic approach also makes it useful as a guide for an advanced course.
Author: Robert H. Crabtree
Publisher: John Wiley & Sons
ISBN: 0471718750
Category : Science
Languages : en
Pages : 600
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Book Description
Fully updated and expanded to reflect recent advances, this Fourth Edition of the classic text provides students and professional chemists with an excellent introduction to the principles and general properties of organometallic compounds, as well as including practical information on reaction mechanisms and detailed descriptions of contemporary applications.
Author: Walter Kaminsky
Publisher: Wiley-VCH
ISBN: 9783527317424
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
With an enormous velocity, olefin polymerization has expanded to one of the most significant fields in polymers since the first industrial use about 50 years ago. In 2005, 100 million tons of polyolefins were produced - the biggest part was catalyzed by metallorganic compounds. The Hamburg Macromolecular Symposium 2005 with the title "Olefin Polymerization" involved topics such as new catalysts and cocatalysts, kinetics, mechanism and polymer reaction engineering, synthesis of special polymers, and characterization of polyolefins. The conference combined scientists from different disciplines to discuss latest research results of polymers and to offer each other the possibility of cooperation. This is reflected in this volume, which contains invited lectures and selected posters presented at the symposium.
