Synthesis of Novel Chiral Bipyrimidine Diphosphine and Aminoalcohol Ligands and Their Application in Asymmetric Catalysis PDF Download
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Author: Gang Chen
Publisher:
ISBN:
Category : Asymmetric synthesis
Languages : en
Pages : 252
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Book Description
Author: Gang Chen
Publisher:
ISBN:
Category : Asymmetric synthesis
Languages : en
Pages : 252
Get Book Here
Book Description
Author:
Publisher:
ISBN: 9789741438600
Category : Catalysis
Languages : en
Pages : 640
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Book Description
A series of N-salicyl-beta-aminoalcohol ligands had been synthesized by three component Mannich type reaction followed by ring opening of oxazolidine derivatives with hydroxylamine hydrochloride. The reactions provided a series of chiral N-salicyl-beta-aminoalcohol ligands in high yields (84-92%) without any racemization. These synthesized compounds were evaluated as ligands for catalytic asymmetric Strecker reactions. N-Benzhydrylaldimines derived from aromatic and aliphatic aldehydes reacted withTMSCN in the presence of 10 mol% of Ti-ligand complex to give the alpha-aminonitriles in excellent yields and in up to >98% ee. In addition, the catalyst loading was successfully reduced to 2.5 mol% which is very effective and extremely simple for large scale synthesis. The presence of 2-propanol is essential to ensure good conversion and reaction rate. The absolute configuration of all products derived from the (S)-ligand was confirmed to be S. Racemization of alpha-aminophenylacetonitriles is catalyzed by weak acids such as silica (SiO[subscript 2]) or even methanol. However, the racemization can be suppressed by addition of either a base such as triethylamine (NEt[subscript 3]) or strong acid such as hydrochloric acid (HCI). Importantly, optically active alpha-aminoacetonitriles can be easily converted to arylglycines by complete hydrolysis with minimal racemization. (>80% and >90% ee). A transition state model to explain the enantioselectivity of the reaction is proposed. The present chiral catalysts showed their catalytic ability in not only asymmetric strecker reaction but also asymmetric Pudovic reaction as well as asymmetric Michael addition.
Author: Marc Lemaire
Publisher: Springer
ISBN: 9783642065385
Category : Science
Languages : en
Pages : 0
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Book Description
The use of phosphine derivatives has historically induced the tremendous development of catalysis (both non-asymmetric and asymmetric). Although the chemistry of amines is more documented, the use of nitrogen-containing ligands only appeared recently. Nevertheless, during the last ten years, the results describing chiral diamine preparations and their uses in asymmetric catalysis and synthesis are increasing faster than their phosphorus counterparts. The reader will find in this volume the most recent methods for the synthesis of chiral diamines as well as their applications in asymmetric catalysis of CC bond formation. Particular attention will be given to spartein and derivatives of such diamines. Recently, the particular properties and the chemistry of amines allowed to obtain catalysts easy to separate and recycle and new types of ligands such as diaminocarbenes, ureas and thioureas. Finally, the complexing properties of some diamines allowed the formation of complexes with chirality "at the metal " which is of major theoretical interest and presents numerous potential applications.
Author: Liqin Qiu
Publisher:
ISBN:
Category : Asymmetric synthesis
Languages : en
Pages : 277
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Author: David A. Regan
Publisher:
ISBN:
Category : Asymmetric synthesis
Languages : en
Pages : 260
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Author: Cian Reid
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Jing Wu
Publisher:
ISBN:
Category : Ligands
Languages : en
Pages : 722
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Author: Jacek Wojaczynski
Publisher: John Wiley & Sons
ISBN: 3527834192
Category : Science
Languages : en
Pages : 692
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Book Description
Chiral Building Blocks in Asymmetric Synthesis A comprehensive introduction to the important classes of chiral building blocks Chirality — the asymmetric quality found in certain chemical compounds — plays an essential role in our world: chiral compounds can be found in biology, pharmaceutical compounds, agrochemicals, and fragrances. The stereoselective preparation of these complex molecular constructions constitutes a challenge. To this end, modern asymmetric synthesis utilizes a variety of valuable and efficient reagents employed as chiral auxiliaries, metal complexes and organocatalysts in stereoselective catalysis, and enantiopure reactants termed as chiral building blocks. In Chiral Building Blocks in Asymmetric Synthesis, the achievements in the fields of preparation of and applications of chiral blocks are presented. In doing so, the book comprehensively discusses the important classes of these reactants as the key for the asymmetric synthesis of chiral molecules. As such, it is an indispensable resource about synthetic methods, as well as possible modifications and transformations of important classes of chiral compounds. It also highlights the importance of their use as reactants and auxiliaries in the preparation of more sophisticated molecules or supramolecular systems. In Chiral Building Blocks in Asymmetric Synthesis readers will also find: Organization according to the most important compound classes — e.g. amino acids, BINOL and its derivatives, terpenes, and others — with an emphasis on synthesis and application A focus on the use of chiral building blocks for the preparation of bioactive compounds and supramolecular assemblies Chiral Building Blocks in Asymmetric Synthesis is a useful reference for organic chemists, catalytic chemists, chemists in industry, medicinal chemists, pharmaceutical chemists, and the libraries that support them.
Author: Patricia Dawn MacLeod
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Cheng-Wei Tom Chang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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