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Conformational Analysis Using Carbon-13-Carbon-13 and Carbon-13-Hydrogen Spin-Spin Coupling Constants (open access)

Conformational Analysis Using Carbon-13-Carbon-13 and Carbon-13-Hydrogen Spin-Spin Coupling Constants

This study consists of four major areas of research. First, the relationship between and was extended to Lrl nil homoallylic couplings and was used to determine the relative degree of puckering in a series of dihydroaromatic carboxylic acids. Second, the effect of coupling contributions transmitted through space were examined by theoretical calculations of the intermediate neglect of differential overlap finite perturbation theory type (INDO-FPT) including selective overlap reduction experiments to determine the sign and magnitude of the major through-space contributions and the effect of the orientation of the substituent upon the vicinal carbon3 carbon coupling. Third, the dependence of the J upon substituent orientation in norbornanes was empirically investigated by the synthesis of a series of lactones and cyclic ethers whose conformation was rigid and known. Fourth, a large number of norbornanes substituted with methyls in the 1, 3, and 7 position and a carbon-13 labeled substituent in the 2 position were synthesized and studied in order to obtain a variety of vicinal C-C couplings; all the NMR parameters for this series of compounds were determined while the carbon13 labeled substituent was varied from methyl to methylene to carbinol to aldehyde and to carboxylic acid.
Date: May 1981
Creator: McDaniel, Cato R., Jr.
System: The UNT Digital Library
The Preparation, Properties, and Reactions of Silenes, Silenoids, and 2-Silanobornenes (open access)

The Preparation, Properties, and Reactions of Silenes, Silenoids, and 2-Silanobornenes

The reaction of chlorodimethylvinylsilane with tertbutyllithium was investigated in the presence of several conjugated dienes. In all cases except with 2,5-dimethylfuran, [2+4] cycloadducts of a silene intermediate are obtained in hydrocarbon solvents. The presence of THF in the reaction mixture suppresses the formation of cycloadducts in favor of 1,3-disilacyclobutanes. In the reaction of dimethylethoxyvinylsilane or dimethylmethoxyvinylsilane with tert-butyllithium the main product is the 1,1-dimethyl2-neopentyl-4-(dimethylalkoxysilyl)silacyclobutane. It is concluded that lithium chloride elimination to give silene intermediates occurs in hydrocarbon solvents. In the presence of strong Lewis bases or when the leaving group on silicon is an alkoxy group, the addition reaction giving a-lithiosilanes occurs and products arising from their coupling reactions are obtained.
Date: December 1981
Creator: Pierce, Richard A. (Richard Austin), 1918-2004
System: The UNT Digital Library
Synthesis of Anthracyclines Related to Adriamycin (open access)

Synthesis of Anthracyclines Related to Adriamycin

This dissertation reports the preparation of several types of anthraquinones structurally related to adriamycin. It describes the synthesis of two types of 2-aminoquinizarin compounds. It also presents two new syntheses of a heterocyclic tetracyclic ring system, similar to the aglicone ring system of adriamycin. A series of 2-aminoquinizarins was prepared by adding several primary amines to quinizarin. Quinizarin was shown to be essentially inert toward secondary amines. Several secondary amine adducts with quinizarin have been prepared, however, by treating the bis-boroacetate ester of quinizarin with the amines. Both types of 2-aminoquinizarin compounds exhibit outstanding potential for possessing antineoplastic activity, and several have been submitted to the National Cancer Institute for testing in their screening program for antineoplastic agents.
Date: May 1981
Creator: White, Roger J.
System: The UNT Digital Library