Photocopy of typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1979. / Bibliography: leaves 172-197. / Microfiche. / xii, 179 leaves ill. 29 cm

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The reaction between alkylidene or arylmethylene triphenyl phosphoranes and sulphonyl fluorides or sulphonic anhydrides has been used to give a variety of α-sulphonyl stabilised phosphorus ylides. Flash Vacuum Pyrolysis (FVP) of alkyl- and arylsulphonyl alkylidene triphenyl phosphoranes leads to two fractions. The first fraction is made up of up to 20 phosphorus containing products, the major one being Ph3PO. The second fraction is a liquid at low temperature which forms a white, insoluble polymeric material on warming to room temperature. Trapping reactions of the liquid with Diels-Alder dienes or chlorine gives unknown and unstable compounds except with anthracene where an unidentified complex is formed. FVP of benzyl- and substituted-benzylsulphonyl alkylidene and phenylmethylene triphenyl phosphoranes proceeds by loss of Ph3P followed by intramolecular insertion of the resulting carbene to form episulphones which lose SO2 to give stilbene or styrene derivatives. In the cases where the phosphorane is an α-sulphonyl ethylidene triphenyl phosphorane, a 1,2-H shift of the carbene can occur to form a vinyl sulphone, which decomposes to vinyl and benzyl radicals and SO2 with formation of bibenzyl products. Where the phosphorane is an α-sulphonyl ortho-substituted-benzylidene triphenyl phosphorane, a second carbene insertion pathway occurs to give eventually benzofuran or benzothiophene and bibenzyl. The Ph3P group reacts with the liberated SO2 to give some conversion to a 2:1 mixture of Ph3PO and Ph3PS, a previously unrecognised reaction. The initially formed stilbene or styrene products can react to a certain extent to form cross over products under the reaction conditions used. A number of α-sulphinyl alkoxycarbonylmethylene triphenyl phosphoranes have been made from alkoxycarbonylmethylene triphenyl phosphoranes, sulphinyl chlorides and Et3N. These ylides exhibit broadening in their 1H and 13C NMR spectra, variable temperature NMR studies indicating the presence of cis and trans rotamers. FVP of these compounds gave Ph3P, Ph3PO, vinyl or substituted vinyl sulphides, alkyl sulphides and an as yet unidentified carbonyl compound. The vinyl or substituted vinyl sulphides are obtained via loss of Ph3PO from the starting ylide followed by insertion of the carbene form of the initially formed thia-acetylene and loss of CO2 from the resulting β-lactone. The other products are obtained from a variety of insertion, rearrangement and elimination reactions of the initially formed carbenes some of which have been elucidated with the help of 13C labelling. Isopropylsulphinyl benzylidene triphenyl phosphorane was synthesised and upon FVP gave Ph3P, isopropyl thiobenzoate and thiobenzoic acid. The formation of isopropyl thiobenzoate is rationalised via an S to C oxygen transfer mechanism of the initially formed carbene, involving the intermediacy of the previously unknown λ4-oxathiirene ring system. A β-keto tri-n-butyl phosphorane, benzoyl butylidene tri-n-butyl phosphorane was synthesised and its FVP performed at room temperature, 300°C and 500°C. The almost complete extrusion of Bun3PO from the ylide at 300°C indicates that much lower temperatures are required for loss of Bun3PO as compared to loss of Ph3PO.

The results of further investigation into the pyrolytic behaviour of alkane- and arenesulphinyl alkoxycarbonyltriphenylphosphoranes are reported. Flash vacuum pyrolysis (FVP) of these ylides at 600°C gives vinyl sulphides, sulphides and aldehydes. The vinyl sulphides and aldehydes are explained by assuming extrusion of Ph3P=O, followed by C-H insertion in the resulting carbene to give a β-lactone. This can either lose CO2 to give the vinyl sulphides or fragment in the opposite sense to give the aldehydes together with unknown products. The sulphides are explained by assuming extrusion of Ph3P, followed by successive loss of CO and CO2. A variable temperature study of Ph3P=C(CO2Et)SOEt has revealed a complex pattern of interdependent restricted rotation of both ester and sulphinyl groups. FVP of the alkanesulphinylbenzylidenetriphenylphosphoranes at 500°C gives the alkyl thiolobenzoates by oxygen transfer in the carbene formed by extrusion of Ph3P. The first three examples of arenesulphinyl benzylidenetriphenylphosphoranes have been prepared. FVP of these at 500°C gives a mixture containing aryl thiolobenzoates formed as above together with ketones, sulphides, thiols, disulphides and stilbene. Mechanisms are suggested for the formation of these products. Four new alkyl sulphonyldiazoacetates have been prepared. FVP of these at 600°C gives vinyl sulphones, while at lower temperatures, products resulting from transfer of oxygen in the carbenes formed by extrusion of N2 predominate.

Sixteen examples of the previously unknown β,γ,β'-trioxo phosphorus ylides have been prepared and fully characterised. Upon flash vacuum pyrolysis (FVP) these undergo clean loss of Ph3PO selectively across the central position to afford diacylalkynes in most cases. The pyrolysis results are discussed in the light of the fully assigned 13C NMR spectra presented and in particular the values of 2jp-C(C=O). Six examples of the higher homologues, the β,γ,β,γ-tetraoxo ylides have also been prepared and are found, quite unexpectedly, to give poor results upon FVP but to undergo moderately successful Ph3PO extrusion to afford trioxoalkynes using conventional pyrolysis. The known β,γ-dioxophosphonium salts required as precursors to these have been characterised by NMR for the first time and are shown to exist predominantly as mixtures of E and Z enol forms in solution. By reaction with oxalyl chloride, a range of higher polyoxo bis ylides has been obtained, including three examples of hexaoxo bis ylides which are remarkable in containing an acyclic series of eight contiguous C=X centres. The 13C NMR spectra for the oxalyl bis ylides are interesting due to the pattern of coupling observed to both phosphorus atoms. These compounds do not in general give any useful results from FVP presumably due to the thermal instability of the expected products. The reactivity of dioxo, trioxo, tetraoxo and oxalyl bis ylides towards a variety of oxidants has been examined and has given promising preliminary results for the formation of vicinal polycarbonyl compounds. Vicinal triones and tetraones are readily obtained and some evidence for a pentaone was obtained in one case. All the products readily form the molecular hydrates with geminal diol structures and these have been characterised spectroscopically. Reaction of the various ylide types with NO2 has been examined and a range of different processes is observed including formation of nitriles accompanied in one case by ring nitration of a phenyl group. A total of twenty five β-aminoacyl ylides derived from N-alkoxycarbonyl protected amino acids have been prepared using a carbodiimide coupling method and have been fully characterised. Upon FVP at 600°C these readily lose Ph3PO to afford protected acetylenic amino acid derivatives and twelve examples of these valuable chiral compounds have been obtained in moderate yield. By standard reactions these products have been transformed into simple chiral analogues of the important neurotransmitter GABA in four cases. Removal of the N-protecting group in the amino acid derived ylides results in a change in pyrolysis behaviour: ethanol is eliminated rather than Ph3PO to give novel cyclic stabilised ylides related in structure to the tetramic acids. Finally, samples of one trioxo ylide, one tetraoxo ylide, one tetraoxo bis ylide and one hexaoxo bis ylide have been sent for solid state structure determination by X-ray methods. The results obtained provide ready confirmation of the important contribution of phosphonium enolate forms to the structures of these but give surprising results as regards the conformational preference for syn and anti alignments of the adjacent C=X units along the chain.

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This dissertation describes the development of a novel ring fragmentation reaction in which cyclic γ-silyloxy-β-hydroxy-α-diazoesters undergo efficient rupture of the Cβ−Cγ bond when treated with tin tetrachloride to provide tethered aldehyde ynoate products with varying tether length, in high yield. Tethered aldehyde ynoates are versatile intermediates and this functional group combination is unique to this fragmentation. The synthetic utility of tethered aldehyde ynoates is highlighted by their predisposition to undergo facile intramolecular [1,3]- dipolar cycloaddition reactions in presence of bistrimethylsylil-α-amino acids to provide 2,5-dihydropyroles. The ability to quickly assemble such structural motifs encouraged studies on the synthesis of steroidal alkaloid solanidine. A new method for the N-amination of oxazolidiones with NH2Cl was investigated and provides efficient access to acyl hydrazines. However, the full scope of the reaction has not been yet fully explored. The study of isopropyl radical additions to N-acylhydrazones and comparison of several stereocontrol elements on the oxazolidinone moiety revealed that all are effective.

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Abstract Methyldiphenylphosphonium cyclopentadienylide, C5H4PMePh2 (II), has been synthesized and characterized spectroscopically and crystallographically, and has been found to exhibit properties consistent with the zwitterionic structure IIb. New group 6 complexes, (η5-C5H4PMePh2)M(CO)3, have been synthesized and fully characterized. Comparisons of ν(CO) of these complexes with those of the isoelectronic (η6-C6H6)M(CO)3 and [(η5-C5H5)M(CO)3]- suggest that the electron donating ability of the ylide is between that of the cyclopentadienyl anion (Cp-) and benzene, but closer to Cp-. The electronic structures of II and of (η5- C5H4PMePh2)Cr(CO)3 have been investigated using ab initio methodologies. Thermal and photochemical substitutions of the CO ligands of (η5-C5H4PMePh2)M(CO)3 (M = Cr, Mo) by equimolar amounts of PMe3 and PPh3 were not observed, but the ylide is displaced photochemically from (η5-C5H4PMePh2)Mo(CO)3 by excess PMe3 to form fac- Mo(CO)3(PMe3)3 while (η5-C5H4PMePh2)Mo(CO)3 reacts with I2 to form [(η5- C5H4PMePh2)Mo(CO)3I]I. One electron oxidations of (η5-C5H4PMePh2)M(CO)3 (M = Cr, Mo, W) have been performed to give the cationic radicals [(η5-C5H4PMePh2)M(CO)3]+, which undergo dimerization to give dicationic metal-metal bonded dimers ((η5-C5H4PMePh2)M(CO)3)2 2+ in the solid state. These complexes have been fully characterized spectroscopically and crystallographically. It has been determined that the chromium dimer ((η5- C5H4PMePh2)Cr(CO)3)2 2+ undergoes dissociation extensively in solution to the persistent radical cation monomer (η5-C5H4PMePh2)Cr(CO)3 +, but that the heavier metal analogues iii ((η5-C5H4PMePh2)M(CO)3)2 2+ (M = Mo, W) dissociate very little, if at all. The Cr-Cr bond distance of the chromium complex is 3.3509(7) Å, which is the longest Cr-Cr bond distance known for a compound not containing some type of ligand bridging the metalmetal bond. The hitherto unknown indenyl-derived ylide, C9H6PMePh2, has been synthesized and characterized spectroscopically and crystallographically. The chromium tricarbonyl complex of this ligand, (η5-C9H6PMePh2)Cr(CO)3, has been synthesized and characterized spectroscopically and crystallographically. This complex is a mixture of two isomers exhibiting planar chirality generated upon coordination of the ligand. This complex represents the first structurally characterized phosphorus noncyclopentadienylide coordinated in an η5 manner. The spectroscopic and crystallographic behaviour of C9H6PMePh2 demonstrates that this ylide behaves much like the related cyclopentadienylides. / Thesis (Ph.D, Chemistry) -- Queen's University, 2007-09-07 11:46:39.391