نتایج جستجو برای: asymmetric catalysis

تعداد نتایج: 90956  

2013
Michael F. Cuccarese Jiazhen J. Li George A. O’Doherty

Over the years, considerable effort has been made toward the development of new synthetic routes to monosaccharides [1]. This interest came primarily from the medicinal chemistry community, as these new routes often provided access to unnatural sugars, which could be of use in structure–activity relationship (SAR) studies. In addition, the synthesis of monosaccharides, and in particular hexoses...

2006
Antonio L. Braga Diogo S. Lüdtke Eduardo E. Alberto

The search for new ligands in asymmetric catalysis is a field of continuing interest. To facilitate practical applications, new ligands should be easy to prepare from simple and easily available starting materials. In this context, the use of chiral nitrogen compounds bearing an organochalcogen moiety and their metal complexes have gained increased importance in the field of asymmetric catalysi...

Journal: :Angewandte Chemie 2002
Ryoji Noyori

Asymmetric catalysis, in its infancy in the 1960s, has dramatically changed the procedures of chemical synthesis, and resulted in an impressive progression to a level that technically approximates or sometimes even exceeds that of natural biological processes. The recent exceptional advances in this area attest to a range of conceptual breakthroughs in chemical sciences in general, and to the p...

2009
Haifeng Du

The Diels–Alder (DA) reaction (or “diene synthesis”) between a diene and a dienophile generates two s bonds stereoselectively and up to four chiral centers in a single step to afford six-membered cyclic compounds. This cycloaddition reaction named after Professor Otto Paul Hermann Diels (1876–1954) and his student Kurt Alder (1902–1958) was discovered in 1928 during studies on the reaction of b...

2007
H. B. KAGAN

The preparation of optically active molecules needs a chiral auxiliary. It is important to use the minimum amount of this auxiliary, and from that point of view asymmetric catalysis is much more advantageous than stoichiometric asymmetric synthesis. Some homogeneous catalysts prepared from chiral complexes have become during the past few years a useful tool in asymmetric synthesis. The complexe...

Journal: :Journal of the American Chemical Society 2001
A M Hafez A E Taggi T Dudding T Lectka

We report a catalytic asymmetric reaction process that involves the use of solid-phase reagents and catalysts that constitute the packing of a series of "reaction columns". This process was applied to the catalytic asymmetric synthesis of beta-lactams, to yield pure products with excellent enantio- and diastereoselectivity. We have identified several advantages to conducting chemical reactions ...

2001
Kristina Hallman

This thesis deals with the design of ligands for efficient asymmetric catalysis and studies of the conformation of the ligands in the catalytically active complexes. All ligands developed contain chiral oxazoline heterocycles. The conformations of hydroxyand methoxy-substituted pyridinooxazolines and bis(oxazolines) during Pd-catalysed allylic alkylations were investigated using crystallography...

Journal: :Organic letters 2000
A M Hafez A E Taggi H Wack W J Drury T Lectka

[structure] A catalytic asymmetric reaction process was designed involving the use of solid-phase reagents and catalysts that constitute the packing of a series of "reaction columns". This process was applied to the catalytic asymmetric synthesis of beta-lactams, yielding pure product after crystallization with exceptional enantio- and diastereoselectivity.

2006
Kuiling Ding

Two strategies for the development of practical asymmetric catalysis have been discussed in this article. The first part of this article focuses on the design and screening of highly efficient and enantioselective chiral catalysts for asymmetric hydrogenation reactions employing combinatorial approach. The second part presents a conceptually new strategy (i.e., “self-supporting” approach) for t...

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