Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Entire DC Network
Palladium-Catalyzed Vinylic Substitution Of Aryl Halides On Polymeric Nitrogen Supports., Chia-Hsing Sun
Palladium-Catalyzed Vinylic Substitution Of Aryl Halides On Polymeric Nitrogen Supports., Chia-Hsing Sun
LSU Historical Dissertations and Theses
The structure of typical palladium complexes used as catalysts in organic synthesis is reviewed; particular attention is paid to the systematic study of palladium catalyzed vinylic substitution on a variety of aryl iodides and bromides (Heck-type vinylation). The general conditions of this process, i.e., a homogeneous catalyst operating at moderate temperature, which requires a proton acceptor to complete the catalyst cycle, are conducive to successful development of a polymer-bound catalyst. Using 4-picoline as a ligand under homogeneous Heck-type vinylation conditions. Morpholine is an adequate base to stabilize the catalytic picoline complex when aryl iodides are condensed with styrene. However, sodium …
Spectral Studies Of Constituents Of Members Of The Family Asteraceae., Karla Ann Wilzer
Spectral Studies Of Constituents Of Members Of The Family Asteraceae., Karla Ann Wilzer
LSU Historical Dissertations and Theses
A phytochemical investigation of ten species of the genus Aster (Family Asteraceae, Tribe Astereae) was carried out. The study involved the following taxa from the southern region of the United States: A. adnatus, A. concolor, A. dumosus x lateriflorus (a hybrid), A. lateriflorus, A. patens, A. praealtus, A. spinosus, A. subulatus var. ligulatus and A. tenuifolius as well as A. umbellatus from Pennsylvania. The chemical analysis of A. praealtus provided umbelliferone and seven prenylated coumarins of which four were new natural products. A ten-carbon acetylenic compound was isolated from A. spinosus. (DELTA)('7)- Sterols were found in A. adnatus which is …
Rearrangements Of Alpha-Halosilanes And Conformational Analysis Of Silanes., Rayomand Jal Unwalla
Rearrangements Of Alpha-Halosilanes And Conformational Analysis Of Silanes., Rayomand Jal Unwalla
LSU Historical Dissertations and Theses
A number of (alpha)-halosilanes, some which are chiral at carbon, have been prepared. Lewis acid-catalyzed rearrangements and thermal rearrangements were performed on ((alpha)-chloroethyl)diphenylmethylsilane. Both the rearrangements proceed cleanly; the major product is formed by the migration of the phenyl group from silicon to carbon. The rearranged product mixture was subjected to a Kumada-type oxidation in which the silicon-carbon is cleaved stereospecifically. Thus the principle has been established that a clean rearrangement can be carried out in a manner which will allow determination of the stereochemistry at the carbon center. Preliminary kinetic studies of the thermolysis of ((alpha)-chlorobenzyl)dimethylphenylsilanes containing p-substituents in …
Models For The Study Of Intramolecular Interactions: Preparation, Structure And Reactivity Of 2-(2'-Acyloxyphenylethynyl)Benzoic Acids., Michael Allen Oliver
Models For The Study Of Intramolecular Interactions: Preparation, Structure And Reactivity Of 2-(2'-Acyloxyphenylethynyl)Benzoic Acids., Michael Allen Oliver
LSU Historical Dissertations and Theses
The hypothesis concerning orientational effects of carboxylate in general-base catalysis is discussed, and the first models that allow proton transfer to the syn lone-pair of the carboxylate during intramolecular general-base catalysis are designed, prepared, and tested. These models use a carbon backbone of two aryl groups linked by a two carbon bridge. The syntheses of 2-(2-hydroxyphenylethynyl)benzoic acid (24) and derivatives used in these studies are described. These derivatives were also needed to evaluate the ethynyl group as the bridge linking the aryls and to aid in the design of more complex models. The hydrolysis of the dichloroacetate ester (26) is …
Plant Germination And Growth Inhibitors From Ceratiola Ericoides And Calamintha Ashei (Herbicides, Allelopathy, Monoterpenes, Phenolics)., Nesrin Tanrisever
Plant Germination And Growth Inhibitors From Ceratiola Ericoides And Calamintha Ashei (Herbicides, Allelopathy, Monoterpenes, Phenolics)., Nesrin Tanrisever
LSU Historical Dissertations and Theses
As part of a chemical-ecological study of the Florida scrub community, Ceratiola ericoides (Empetraceae) and Calamintha ashei (Lamiaceae) were chemically investigated for natural products with possible allelochemical activities. The chromatographic separations and chemical investigations were guided by germination and radicle growth bioassays performed on seeds of commercial lettuce (Lactuca sativa) and Schizachyrium scoparium, a native grass of the Florida sandhill community. From the dichloromethane extract of aerial parts of C. ericoides, 2', 4'-dihydroxychalcone, the dihydrochalcones angoletin and 2',6'-dihydroxy-4-methoxy-3',5'-dimethyldihydrochalcone, the flavanones 8-methylpinocembrin, 6,8-dimethylpinocembrin and 7-hydroxyflavanone were isolated along with the triterpenes erytrodiol and ursolic acid. Significant inhibition on S. scoparium radicle …