Results 271 to 280 of about 158,943 (323)

Nucleophilic substitution catalyzed by a supramolecular cavity proceeds with retention of absolute stereochemistry.

Journal of the American Chemical Society, 2014
While the reactive pocket of many enzymes has been shown to modify reactions of substrates by changing their chemical properties, examples of reactions whose stereochemical course is completely reversed are exceedingly rare.
Chen Zhao, F. Toste, K. Raymond, R. Bergman   +3 more
semanticscholar   +1 more source

Stereochemistry of the methoxyphthioceranes

Journal of the Chemical Society D: Chemical Communications, 1970
The phthiocerols, RCH(OMe)·CHMe·[CH2]4·CH(OH)·CH2·CH(OH)·[CH2]nMe (R = Et or Me, n= 20 and 22), constituents of tuberculolipids, have been converted, by substituting H for each OH, into the corresponding methoxyphthioceranes A and B (R = Et or Me, respectively).
Nicholas Polgar, Kenneth Maskens
openaire   +3 more sources

Teaching Metathesis “Simple” Stereochemistry

Science, 2013
Background Transition metal–catalyzed alkene metathesis has revolutionized organic synthesis during the last two decades, even though the commonly used catalysts do not provide kinetic control over the stereochemistry of the newly formed double bonds. It
A. Fürstner
semanticscholar   +1 more source

The Influence of Solubilizing Chain Stereochemistry on Small Molecule Photovoltaics

, 2014
Three stereochemically pure isomers and two isomeric mixtures of a solution‐processable diketopyrrolopyrrole‐containing oligothiophene (SMDPPEH) have been used to study the effect of 2‐ethylhexyl solubilizing group stereochemistry on the film morphology ...
R. B. Zerdan, N. Shewmon, Yu Zhu, John P. Mudrick, Kyle J. Chesney, J. Xue, R. K. Castellano   +6 more
semanticscholar   +1 more source

The synthesis and stereochemistry of desacetoxymatricarin and the stereochemistry of matricarin

Tetrahedron, 1969
Abstract Desacetoxymatricarin (IV), a sesquiterpene lactone found in the genus Artemisia and in the form of 8-hydroxy and acetoxy derivatives in the genus Achillea, has been synthesized from α-santonin by a sequence that allows assignment of the full stereochemistry. The stereochemistry of matricarin (V) has also been determined.
J.N. Marx, S. Eguchi, Emil H. White
openaire   +2 more sources

Asymmetric synthesis of (+)- and (-)-pauciflorol F: confirmation of absolute stereochemistry.

Organic Letters, 2013
An efficient, formal enantioselective synthesis of (+)- and (-)-pauciflorol F has been achieved using a recently introduced oxazolidinone controlled torquoselective Nazarov reaction.
Daniel J. Kerr, Michael Miletic, Narasimhulu Manchala, J. White, B. Flynn   +4 more
semanticscholar   +1 more source

Revised stereochemistry of ceramide-trafficking inhibitor HPA-12 by X-ray crystallography analysis.

Organic Letters, 2013
In response to Berkeš's report revising the stereochemistry of HPA-12, an important ceramide-trafficking inhibitor that was discovered and synthesized and its stereochemistry determined in 2001, the synthesis and the stereochemistry were reinvestigated ...
M. Ueno, Yiyong Huang, A. Yamano, S. Kobayashi   +3 more
semanticscholar   +1 more source

The rich stereochemistry of eight-vertex polyhedra: a continuous shape measures study.

Chemistry, 2005
A stereochemical study of polyhedral eight-vertex structures is presented, based on continuous shape measures (CShM). Reference polyhedra, shape maps, and minimal-distortion interconversion paths are presented for eight-vertex polyhedral and polygonal ...
D. Casanova, Miquel Llunell, P. Alemany, S. Alvarez   +3 more
semanticscholar   +1 more source

Stereochemistry of lactide polymerization with chiral catalysts: new opportunities for stereocontrol using polymer exchange mechanisms.

Journal of the American Chemical Society, 2002
The synthesis of chiral aluminum and yttrium alkoxides and their application for lactide polymerization are reported. The complexes (SalBinap)MOR [4, M = Al, R = (i)Pr; 5, M = Y, R = (CH(2))(2)NMe(2)] are synthesized by reacting the ligand (SalBinap)H(2)
Tina M. Ovitt, G. Coates
semanticscholar   +1 more source

Stereochemistry of iron in deoxyhaemoglobin

Nature, 1982
The EXAFS of human deoxyhaemoglobin closely resembles that of a synthetic model in which the displacement of the iron from the mean porphyrin plane is 0.426 +/- 0.004 A, similar to the displacement of 0.56 +/- 0.03 A found by single crystal X-ray analysis of deoxyhaemoglobin.
J. E. Hahn, S. Samar Hasnain, Max F. Perutz, J. L. Sessler, P. J. Duke   +4 more
openaire   +5 more sources