No description available.

No description available.

A series of new 1,5-dimethyl-6-0x0-verdazyl radicals were prepared bearing either a hydroquinone or the 3,5-di-tertiary-butyl phenol substituent in the 3 position of the verdazyl ring as precursors to verdazyl 1 semiquinone diradical anions or verdazyl 1 phenoxyl diradicals. All radical precursor tetrazanes were characterized by 'H / 13c NMR and FTIR spectroscopies, MS, and elemental analysis. Oxidation of the tetrazane precursors with NaI04 or A ~ + gave verdazyl radicals as microcrystalline solids. All verdazyl radicals were characterized by EPR, UV-visible, and FTIR spectroscopies, and high-resolution MS or elemental analysis. All attempts to oxidize the hydroquinone or phenol moieties were unsuccessful as was coordination chemistry with those verdazyls bearing a chelating ortho-hydroquinone. Several molecules were synthesized as building blocks towards tris(2,6- disubstituted-4-pyridy1)methyl radicals where the substituents were ether chloro- or methoxy- groups. All of these building blocks (aldehydes, ester, alcohol, and ketone) were characterized by 'H / 13c NMR and FTIR spectroscopies, MS, and elemental analysis. All attempts to insert a third ring onto bis(2,6-dichloro-4-pyridy1)ketone to give the radical precursor triarylmethanol have been unsuccessful. Supervisor: Dr. R. G. Hicks (Department of Chemistry)

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xxiv, 173 p.: ill. (some co.). Includes abstract and vita. Advisor: Terry A. Miller, Dept. of Chemistry. Includes bibliographical references (p. 171-173).

Thesis (M.S.)--Central Connecticut State University, 2002. / Thesis advisor: Michael A. La Fontaine. " ... in partial fulfillment of the requirements for the degree of Master in Natural Science-Chemistry." Includes bibliographical references (leaves 61-66). Also available via the World Wide Web.

No description available.

No description available.

The homolytic Brook rearrangement is discussed and homolytic fragmentations of epoxides and epoxysilane chemistry are reviewed. Thiyl radical induced isomerisation was performed on spiro alkenylepoxysilanes to generate novel alkenyl-α-trimethylsilylaldehydes rather than the products of radical Brook rearrangement. The trimethylsilylaldehydes were shown to isomerise on heating to silyldienol ethers and, via the addition of a Grignard reagent, to act as stereoselective vinyl cation equivalents. Attempts to extend the scope of the isomerisation to non-rigid systems met with failure. A review of the antibiotic Roseophilin is presented. Cycloaddition-fragmentation approaches to medium and large rings are reviewed as a prelude to our first route, the proposed Michael addition-retro-aldol fragmentation of the Diels-Alder adduct derived from isopropyl-cyclopentadiene and cyclodec- 2-yn-1-one. The novel ynone, synthesised via the intramolecular Friedel-Crafts acylation of 10-trimethylsilyl-9-decynoyl chloride, was found to isomerise readily to bicyclo[4.4.0]dec-1(6)-en-2-one therefore the model Diels-Alder reaction with cyclopentadiene was effected in one-pot from the cyclisation precursor. Details of the attempted fragmentation of tricyclo[10.2.1.0^2,11]pentadeca-2(11),13-dien-3-one are then described but, due to inconclusive results, an alternative study was instigated. The use of free-radical macrocyclisations in the synthesis of large rings is reviewed with particular reference to the synthesis of natural products. Three strategies for the formation of a bicyclo[10.2.1]pentadecanone skeleton are reported, and subsequent model studies described. Cuprate additions to vinyl lactones and epoxides are discussed. The preferred strategy, involving a cycloalkyl tether between the radical donor and radical acceptor groups, was extended to a system which was derived from the addition of various cuprates to 2-oxabicyclo[3.3.0]oct-7-en-3-one The preparation of cuprates derived directly from 6-iodohexan-1-ol and 1-chloro-6-iodohexane is described. The trans- cuprate addition products were converted successfully to bicyclo[10.2.1]pentadec-12-en-3-one, and the cis- analogues, accessible through a novel regio- and stereoselective hydroboration-fragmentation reaction of 7- (6'-chlorohexyl)-2-oxabicyclo[3.3.0]oct-7-en-3-one, led to bicyclo[10.2.1]pentadec- 13-en-3-one. The successful cyclisations of model oximes, to form nitrones having the correct connectivity for the third ring of Roseophilin, are described. Cuprate additions to 6-(1'-methylethyl)-2-oxabicyclo[3.3.0]oct-7-en-3-one resulted in anti- attack; the cis- adducts were inaccessible via the above methodology but a few intermediates in the trans- series were prepared. Future routes and modifications to the methods developed are then discussed.

No description available.

Restricted Hartree-Fock calculations, with explicit non-empirical calculation of all integrals, are presented for the ground states and some low-lying excited states of eight triatomic radicals (BF2, NH2, HBF, HCO, HNF, FCO, NF2, FO2). Geometries are calculated for these species, and the results related to experiment where possible. The nature of the bonding in each species is discussed. The effect of varying the size of the Gaussian basis sets employed was examined intensively, with particular attention being paid to changes in the total calculated energy, the optimal geometry, bonding and spin density distribution. It was concluded that for reliable geometry predictions a basis of 9 s and 5 P Gaussian functions was required on each first row atom, preferably augmented by polarisation functions possessing higher orbital angular momentum quantum number. This is particularly necessary to obtain the correct bond angles for hydrides. To predict spin densities accurately a basis set of essentially Hartree-Fock quality, possessing at least 11 s functions, is required. For this latter application considerations of balancing the size of the representation on the various atoms in the molecule is particularly crucial.