Synthesis and Catalytic Ability of Diazaphospholenes PDF Download
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Author: Matt Adams
Publisher:
ISBN:
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Languages : en
Pages : 0
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Book Description
This thesis presents a facile entry into diazaphospholene catalysis, harnessing pre- catalysts formed through the reaction of diazaphospholene-bromide compounds with neopentyl alcohol, to afford crystalline pre-catalysts. Their application in the hydroboration of imines and 1,4-reductions gives novel insight into their reactivity, as these heterocycles had yet to be employed in these catalyzed reactions. Mechanistic insights into the role of the catalyst, as well as potential decomposition pathways were explored. Next, enantioenriched diazaphospholene pre-catalysts were developed. These chiral pre-catalysts were applied in the asymmetric hydroboration of imines, to afford amines with enantiomeric ratios of up to 88:12. The monoamine oxidase inhibitor drug Rasagiline (employed in the treatment for Parkinson's disease) was synthesized through these methods affording high selectivity and is the first asymmetric synthesis of this drug. Finally, efforts towards the use of diazaphospheniums as Lewis acids in the splitting of dihydrogen, and hydrogenation of imines are described.
Author: Matt Adams
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis presents a facile entry into diazaphospholene catalysis, harnessing pre- catalysts formed through the reaction of diazaphospholene-bromide compounds with neopentyl alcohol, to afford crystalline pre-catalysts. Their application in the hydroboration of imines and 1,4-reductions gives novel insight into their reactivity, as these heterocycles had yet to be employed in these catalyzed reactions. Mechanistic insights into the role of the catalyst, as well as potential decomposition pathways were explored. Next, enantioenriched diazaphospholene pre-catalysts were developed. These chiral pre-catalysts were applied in the asymmetric hydroboration of imines, to afford amines with enantiomeric ratios of up to 88:12. The monoamine oxidase inhibitor drug Rasagiline (employed in the treatment for Parkinson's disease) was synthesized through these methods affording high selectivity and is the first asymmetric synthesis of this drug. Finally, efforts towards the use of diazaphospheniums as Lewis acids in the splitting of dihydrogen, and hydrogenation of imines are described.
Author: Erin Norah Welsh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Diazaphospholene (DAP) synthesis and reactivity has been emerging over the last two decades. Recently, DAPs have been employed as catalysts for asymmetric reduction transformations. Specifically in the Speed group we use DAP catalysts for asymmetric reduction of imines. This thesis provides a comprehensive overview of the synthetic procedures employed to manipulate the substituents surrounding the DAP scaffold. The subsequent investigation involved testing each isolated DAP compound to assess its enhanced reactivity and selectivity in imine reduction. Initially, the objective was to produce DAP variants with different substituents around the stereogenic centre, specifically larger aryl or alkyl groups that offer increased steric hindrance. We hypothesized that these bulkier substituents would establish a more restrictive stereochemical environment around the phosphorus centre, thereby improving enantioselectivity. However, this led to only one DAP variant that had comparable reactivity and selectivity to the current best DAP. The synthesis of DAPs containing larger aryl or alkyl groups around the stereogenic centre led to more efficient syntheses of 1-dibenzothiophene derivatives and 3- bromonaphthothiophene as starting materials for additional DAP derivatives. However, neither DAPs were fruitful for improved reactivity or selectivity for imine reduction. Considering the limited success achieved when modifying the substituents around the stereogenic centre, it became apparent that exploring alternative strategies was necessary. Consequently, attention was shifted towards alternating the backbone of the DAP scaffold. This led to a more rigid DAP that has shown improved enantioselectivity for imine reduction to make acyclic and exocyclic amines.
Author: Chieh Hung Tien
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Catalysis plays a key role in the industrial production of many refined goods. Catalysts derived from precious metals are especially prevalent in industry due to their high stereoselectivity, and low loadings. To alleviate the reliance on precious metals, catalysts derived from cheaper, more abundant main group elements have attracted much attention in recent years. 1,3,2-Diazaphospholenes developed by Gudat, Kinjo, and our group have shown great potential in the reduction of various unsaturated carbons including imines, carbonyls, olefins, etc. In an effort to uncover catalytic activity in more elaborate heterocycles, I have developed a new class of hydroboration catalysts, namely 1,2,4,3-triazaphospholenes. The synthesis towards 1,2,4,3-triazaphospholenes and their reactivity in the racemic and non-racemic hydroboration of imines and carbonyls are disclosed herein.
Author: Jianbo Wang
Publisher: World Scientific Publishing Europe Limited
ISBN: 9781786348890
Category : Science
Languages : en
Pages : 560
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Book Description
Diazo compounds are versatile substances with diverse transformations in organic synthesis and other fields. Studies of diazo compounds have been ongoing for a very long time but still attract significant attention within the organic chemistry community, with new papers related to diazo compounds appearing at a daily pace. Over the past twenty years, there have been over fifty reviews and accounts related to the reactions of diazo compounds, but most of them cover limited aspects of diazo compounds. In addition to organic synthesis, diazo compounds have found applications in interdisciplinary fields such as material sciences, chemical biology and also polymerization.In this comprehensive book, the authors cover the most recent advances in the fields related to diazo compounds, including the application of donor-acceptor carbenes, carbene-based cross-coupling reactions and polymerizations, as well as the breakthrough in catalytic asymmetric carbene O-H, S-H, and N-H bond insertions. They also cover the application of flow chemistry in diazo reactions. The authors aim to provide a contemporary and comprehensive review for investigators engaged in or with interest in diazo compounds to boost further developments in this fascinating field.
Author: Francois Terrier
Publisher: John Wiley & Sons
ISBN: 3527656162
Category : Science
Languages : en
Pages : 488
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Book Description
This book provides a comprehensive overview of nucleophilic aromatic substitutions, focusing on the mechanistic and synthetic features that govern these reactions. The first chapter presents a detailed mechanistic analysis of the factors determining the feasibility of SNAr substitutions, providing decisive information to predict regioselectivity of many reactions and to define the conditions for concerted SNAr processes. Reflecting the key role played by these species as intermediates in most SNAr reactions, chapter 2 then discusses the chemistry of anionic sigma-complexes. Chapter 3 describes the concept of superelectrophilicity in SNAr substitutions, as it has recently emerged from the reactivity of strongly electron-deficient aromatic and heteroaromatic structures. The numerous synthetic applications are considered in depth in the chapters 4 and 5 that follow on intermolecular and intramolecular nucleophilic aromatic substitutions. Then, chapter 6 focuses on substitutions proceeding formally through displacement of a hydride ion, a hot topic in the field. The final chapter brings together concise yet comprehensive discussions surrounding SNAr photosubstitutions, radical substitutions, and ANRORC substitutions. Authored by a highly respected chemist who has contributed greatly to the field over the past two decades, this is a valuable information source for all organic chemists working in academia or the pharmaceutical and agrochemical industries.
Author: Pierre H. Dixneuf
Publisher: Springer
ISBN: 3030109550
Category : Science
Languages : en
Pages : 309
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Book Description
This volume presents the latest developments in the use of organometallic catalysis for the formation of bulk chemicals and the production of energy, via green processes including efficient utilization of waste feedstocks from industry. The chemistry of carbon dioxide relating to its hydrogenation into methanol –an eco-friendly energy storage strategy– and its uses as C1 synthon for the formation of important building-blocks for fine chemicals industry are covered. Catalytic hydrogenations of various functional groups and hydrogen transfer reactions including the use of first row metal catalysts are presented as well as the conversion of alcohols to carboxylates via hydrogen transfer with a zero-waste strategy using water. Transformation of renewable or bio-based raw materials is surveyed through alkene metathesis and C–O bond activations and functionalizations. A green aspect for selective formation of C-C, C-O and C-N bonds involves direct regioselective C–H bond activations and functionalizations. These transformations can now be promoted under mild reaction conditions due to the use photoredox catalyts. C–H bond oxidation using visible light leads mainly to the formation of C–O and C–N bonds, whereas cross-coupled C–C bonds can be formed through the radical additions on (hetero) arenes using photoredox assisted mechanism.
Author: Xiao-Feng Wu
Publisher: John Wiley & Sons
ISBN: 3527831894
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: Pietro Tundo
Publisher: Springer
ISBN: 3319300733
Category : Science
Languages : en
Pages : 614
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Book Description
Since the industrial revolution, chlorine remains an iconic molecule even though its production by the electrolysis of sodium chloride is extremely energy intensive. The rationale behind this book is to present useful and industrially relevant examples for alternatives to chlorine in synthesis. This multi-authored volume presents numerous contributions from an international spectrum of authors that demonstrate how to facilitate the development of industrially relevant and implementable breakthrough technologies. This volume will interest individuals working in organic synthesis in industry and academia who are working in Green Chemistry and Sustainable Technologies.
Author: Alan R. Katritzky
Publisher: Academic Press
ISBN: 0124202098
Category : Science
Languages : en
Pages : 293
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Book Description
Established in 1960, Advances in Heterocyclic Chemistry is the definitive serial in the area—one of great importance to organic chemists, polymer chemists and many biological scientists. Written by established authorities in the field, the comprehensive reviews combine descriptive chemistry and mechanistic insight and yield an understanding of how the chemistry drives the properties. - One of great importance to organic chemists, polymer chemists and many biological scientists - Written by established authorities in the field, the comprehensive reviews combine descriptive chemistry and mechanistic insight and yield an understanding of how the chemistry drives the properties
Author: Julian R.H. Ross
Publisher: Elsevier
ISBN: 0081000529
Category : Technology & Engineering
Languages : en
Pages : 403
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Book Description
Contemporary Catalysis: Fundamentals and Current Applications deals with the fundamentals and modern practical applications of catalysis. Topics addressed include historical development and the importance of heterogeneous catalysis in the modern world, surfaces and adsorption, the catalyst (preparation and characterization), the reactor (integral and differential reactors, etc.), and an introduction to spectroscopic and thermal characterization techniques. Building on this foundation, the book continues with chapters on important industrial processes, potential processes and separate chapters on syngas production, Fischer Tropsch synthesis, petroleum refining, environmental protection, and biomass conversion. Contemporary Catalysis is an essential resource for chemists, physical chemists, and chemical engineers, as well as graduate and post graduate students in catalysis and reaction engineering. - Covers all aspects of catalysis in a carefully organized text - Includes material on historical development - Provides a wide range of student tasks, case studies, and supplementary, web-based materials that are regularly updated
