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asymmetric carbon atom

The Columbia Encyclopedia, Sixth Edition | Date: 2008

asymmetric carbon atom see isomer .

Author not available, ASYMMETRIC CARBON ATOM., The Columbia Encyclopedia, Sixth Edition 2008



The Columbia Encyclopedia, Sixth Edition. Copyright 2008 Columbia University Press

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Advances in Asymmetric Synthesis
Pharmaceutical Technology; 9/1/2007; Van Arnum, Patricia; 2152 words ; ... catalytic hydroformylation, asymmetric hydrogenation, and biocatalysis ... play an important role in asymmetric synthesis. Catalytic hydroformylation ... aldehydes in a perfectly atom economical transformation ... alkenes, dihydrogen, and carbon monoxide, enantioselective ... potential applications of ... Read more
ASYMMETRIC SYNTHESIS OF (S)-2-AMINO-3-(1-NAPHTHYL)PROPANOIC ACID VIA CHIRAL NICKEL COMPLEX. CRYSTAL STRUCTURE, CIRCULAR DICHROISM, ^sup 1^H AND ^sup 13^C NMR SPECTRA OF THE COMPLEX
Collection of Czechoslovak Chemical Communications; 9/1/2005; Popkov, Alexander; Císarová, Ivana; Sopková, Jana; Jirman, Josef; Et al; 5073 words ; ... benzylprolinamide) was used for preparative asymmetric synthesis of the non-coded amino acid ... many other chiral synthons, they enable asymmetric synthesis of substituted prolines from ... this article we describe a preparative asymmetric synthesis of non-coded amino acid 3 ... 2^ or Br substituents on the ... Read more
Chiral phenyl-bis(oxazoline) as an efficient auxiliary for asymmetric catalysis *.(Report)
Pure and Applied Chemistry; 4/1/2008; Nishiyama, Hisao Ito, Jun-ichi Shiomi, Takushi Hashimoto, Toru Miyakawa, Takeshi Kitase, Megumi; 1893 words ; ... catalytic efficiency for asymmetric conjugate reduction of [alpha],[beta]-unsaturated carbonyl compounds and reductive aldol ... aldehydes and ketones. Keywords: asymmetric catalysis; rhodium; oxazoline ... including molecular catalysis and asymmetric synthesis, because the auxiliaries ... substituent ... Read more
Commercial catalysts: over the past decade CACHy catalysts have developed from an academic curiosity to commercial catalysts. John Blacker and Michael North discuss their development and potential.(Catalytic Asymmetric CyanoHydrin)
Chemistry and Industry; 6/20/2005; Blacker, John North, Michael; 2366 words ; ... isolated and cloned. (4) Asymmetric cyanohydrin synthesis also ... biocatalysis and organocatalysis of asymmetric cyanohydrin synthesis do ... cyanohydrin does not revert to a carbonyl compound and is stable to ... metal-based catalysts for asymmetric cyanohydrin synthesis. (8 ... CACHy class of catalysts ... Read more
Asymmetric syntheses: ligand and catalyst systems for asymmetric reactions are moving from the R&D stage to large-scale production, stimulating further research. (Catalysis).(conference in Cambridge)
Chemistry and Industry; 1/20/2003; Winder, Robert; 1289 words ; The first Forum on Asymmetric Synthesis and Technologies ... in successfully launching asymmetric technologies in a commercial ... crystallisation, enzymic resolution and asymmetric synthesis. While one of these ... has recently added two new asymmetric technologies to its 'technology ... commercialisation ... Read more
Synthesis of optically active heterocyclic compounds using Pd-catalyzed asymmetric reactions as a key step *.(palladium)(Report)
Pure and Applied Chemistry; 4/1/2008; Sodeoka, Mikiko Hamashima, Yoshitaka; 3991 words ; ... addition of amine, and conjugate reduction have been developed. Asymmetric synthesis of biologically interesting heterocyclic compounds ... torcetrapib, and warfarin, was achieved by using these Pd-catalyzed asymmetric reactions as a key step. Keywords: torcetrapib; warfarin; BMS-204352; asymmetric ... Read more
Gr-2. Atom labels and other chemically significant text.(GRAPHICAL REPRESENTATION STANDARDS FOR CHEMICAL STRUCTURE DIAGRAMS **)
Pure and Applied Chemistry; 2/1/2008; Brecher, Jonathan; 4580 words ; ... Consider a simple case such as shown. A carbon atom is the first atom in the label, and ... fill the three open valences on the carbon atom. There are no more atoms, and no open ... more complex example. Again, the first carbon atom has three remaining valences. In this ... Read more
Asymmetric Structural Motions of the Homomeric [alpha]7 Nicotinic Receptor Ligand Binding Domain Revealed by Molecular Dynamics Simulation
Biophysical Journal; 11/1/2003; Henchman, Richard H; Wang, Hai-Long; Sine, Steven M; Taylor, Palmer; McCammon, J Andrew; 9068 words ; ... Marsili, 1980), which use the united atom representation for nonpolar hydrogens ... Angstrom] cubic grid centered on the atom C189:S^sub y^ with grid spacing ... positions of the nitrogen and carbonyl carbon atoms of ACh from the 50,000 docked ... translates to 0.06 k^sub B^T per atom, still a ... Read more
Stereoselectivity in Ene Reactions with ^sup 1^O2: Matrix Effects in Polymer Supports, Photo-oxygenation of Organic Salts and Asymmetric Synthesis
Photochemistry and Photobiology; 9/1/2006; Griesbeck, Axel G; Bartoschek, Anna; Neudörfl, Jörg; Miara, Claus; 5832 words ; ... as ammonium salts. Moderate asymmetric induction was observed for ... photo-oxygenation (1-3). The atom economy of such a process is ... peroxide, that can only reach an atom economy of 48%, if calculated ... abstraction of an allylic hydrogen atom and shift of the double bond ... abstraction of an ... Read more
Synthesis and biologic evaluation of monocationic asymmetric ^sup 99m^Tc-nitride heterocomplexes showing high heart uptake and improved imaging properties
The Journal of Nuclear Medicine; 5/1/2003; Boschi, Alessandra; Uccelli, Licia; Bolzati, Cristina; Duatti, Adriano; Et al; 5565 words ; ... N)(PNP)(L)]^sup +^ . Notably, the asymmetric [^sup 99m^Tc-(N)(PNP)(L)]^sup +^ heterocomplexes ... groups attached to both the nitrogen atom of the dithiocarbamate ligand and ... determining the selective formation of asymmetric ^sup 99m^Tc-nitride heterocomplexes ... heart-to-liver uptake ratios for the ... Read more

Related entries from encyclopedias, dictionaries, and thesauruses

Amino Acid
Biology ... amino group, the carboxylic acid group, a hydrogen, and a characteristic side chain all attached to one carbon atom, designated the α -carbon. Each type of α -amino acid has a unique side chain that determines its properties and its role in proteins. The side chains (or "R" groups) can range ... Read more
Le Bel, Joseph-Achille
Chemistry: Foundations and Applications ... established the relation between optical activity and asymmetric carbon compounds. Le Bel was born into a wealthy family that ... in optical isomers. He argued that if a tetravalent carbon atom combined with four different groups, as in tartrate, the carbon must be asymmetric in ... Read more
chiral
The Oxford Pocket Dictionary of Current English chi·ral / ˈkīrəl / • adj. Chem. asymmetric in such a way that the structure and its mirror image are not superimposable. Chiral compounds are typically optically active; large organic molecules often have one or more chiral centers where four different groups are attached to a carbon ... Read more
Joseph Achille Le Bel
The Columbia Encyclopedia, Sixth Edition ... optical activity—the presence of two forms of the same organic molecule, one a mirror image of the other—is due to an asymmetric carbon atom bound to four different groups. For this contribution he is regarded as the cofounder of stereochemistry, with J. H ... Read more
stereochemistry
Britannica Concise Encyclopedia ... Jacobus H. van't Hoff and Joseph-Achille Le Bel (1847–1930) had independently explained in 1874 how a molecule with a carbon atom bonded to four different groups has two mirror-image forms. Stereochemistry deals with stereoisomers and with asymmetric synthesis . John Cornforth (b. 1917) and Vladimir ... Read more

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