This research is concerned with determining whether the previously reported synthesis of tropolone by the solvolysis of the dichloroketene-cyclopentadiene adduct in sodium acetate and acetic acid could be used to prepare 2-alkyltropones from the adducts of alkylhaloketenes and cyclopentadiene. The information obtained from these rearrangements could be useful in determining the mechanism of the ring expansion of halogenated ketene-cyclopentadiene adducts to tropone derivatives.

The scope of the cycloaddition reaction between .eta.-5-cyclopentadienyliron(II) dicarbonyl-.eta.-1-cyclopentadiene (1.12a) and electrophilic olefins (1.4) and acetylenes (1.5) producing 7-syn-.eta.-5-cyclopentadienyliron(II) dicarbonyl-.eta.-1-bicyclo 2.2.1 hept-5-enes (2.1) and 7-syn-.eta.-5-cyclopentadienyliron(II) dicarbonyl-.eta.-1-bicyclo 2.2.1 hept-2,5-dienes (2.2), respectively, is found to be general for non-sterically hindered olefins and bis-activated acetylenes. The range of reactive 1.4 compounds is extended to include some sterically hindered olefins through precoordination of the olefin to diethylchloroalane or ethyldichloroalane. In contrast to all other acyclic cis and trans-1,2-disubstituted olefins, maleonitrile (1.41) cycloadds with 1.12a with complete retention of alkene stereochemistry. The relative rates for the cycloaddition between 1.12a and 1.41 in benzene, dichloromethane, and methanol are found to be 1:2:4, respectively. These stereochemical and kinetic results are more consistent with a concerted 4+2 cycloaddition than a two-step dipolar 3+2 cycloaddition. A dramatic stereochemical dependence on solvent polarity is observed in the cycloadducts resulting from the reaction of 1.12a with 1.41. Depending on the solvent the Alder "endo" rule is obeyed (methanol) or flagrantly violated (benzene). Reaction of 2.1 with ammonium cerium(IV) nitrate, bromine, or chlorine in acetonitrile containing excess sodium azide gives bicyclo 2.2.1 hept-5-ene-7-syn-carbonylazides (3.4). The reaction is found to be general using 1,2-disubstituted 2.1 compounds with bromine or chlorine. The thermally induced rearrangement of 3.4 compounds in refluxing toluene-tert-butanol gives 7-syn-t-Boc-aminobicyclo 2.2.1 hept-5-enes (4.4) in good yield. This is the first high yield stereospecific synthesis of 4.4 compounds. Furthermore, the synthetic equivalency of 1.12a is shown to include 5-carbonylazide-1,3-cyclopentadiene (3.9) and 5-t-boc-amino-1,3-cyclopentadiene (4.5) as well as 5-carbomethoxy-1,3-cyclopentadiene (3.10) 11.12 .

Xia, Hai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1977. / Also available via the Internet.

Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The thermal decomposition of 2,3,4,5-tetraphenyldiazo cyclopentadiene in pyridine and methyl pyridines has been found to provide a route to the corresponding pyridinium 2,3,4,5-tetraphenyl-cyclopentadienylide. This procedure has been extended to include decomposition of the diazo compound in derivatives of Group V and VI elements and a route to a series of hitherto unreported tetraphenyloyclopentadienylides has been established. Triphenyl-phosphonium, triphenylarsonium, and triphenyIstibonium 2,3,4,5-tetraphenylcyclopentadienylides have been isolated as stable crystalline solids and evidence has been Sound for the existence of the triphenylbismuthonium analogue. Diphenylsulphoniumi methyIphenylsulphonium, and diphenylselenonium 2,3,4,5-tetra-phenyloyclopentadienylides have also been shown to have unusual stability. The mechanism of the decomposition reaction of 2,3,4,5- tetraphenyldiazocyclopentadiene is discussed and is considered to proceed by initial decomposition of the diazo compound to tetraphenyloarbenacyclopentadiene followed by eleotrophilic attack on a suitable heteror-atem group, containing a lone pair of electrons. A comparative study of the properties and the reactivities of the tetraphenylcyclopentadienylides with carbonyl compounds and nitrosobenzene has been made. The pKa's of some of the ylide conjugate acids were determined in 95% ethanol solution and it appears that for the similarly substituted ylidos there is no: consistent parallel between nucleophilicity and basicity. The thermal decomposition of other diazocyclopentadienes, including the 2,3,4,5-tetrachlora-, 2,3,4-tripheny1-1 5-bromo-2,3,4-triphenyl-, and 5-chloro-2,3,4-triphenyl- derivatives, occurred uncontrollably and attempts to obtain ylides failed when these diazo compounds were subjected to analogous conditions employed for 2,3,4,5-tetraphenyldiazocyclopentadiene. Phosphines were found to couple readily with substituted diazocyolopentadienes to form the corresponding phosphazines with the exception of the reaction between triphenylphosphine and 2,3,4,5-tetraphenyldiazocyclopentadiene. Evidence suggests that: these phosphazines, in acidic media, are protonated at the nitrogen atom rather than at the five-membered ring. Pyridinium 2,3,4-triphenyIcyclopentadienylide was prepared by alkylation of pyridine with 5-bromo-2,3,4-triphonyloyclo-pentadiene in a solution of nitromethane and subsequent basi-fication. In an attempt to prepare the analogous phosphomium ylide it was found that: triphonylphosphine in nitromethane led to reduction of the bromo compound. However when this reaction was carried out: in the absence of solventtriphenyl-(2,3,4-triphenyIcyclopentadienyl)phosphonium bromide was isolated. It has been found that tmiphenylarsine oxide and 2,3,4-triphenyloyclopentadiene undergo a reaction in triethylamine and phosphorus pentoxide to form triphenylarsonium 2,3,4- triphenyIeyclopentadienylide, and that' when the reaction is carried out in acetic anhydride the 5-acetyl ylide is formed. Some electrophilic substitution reactions on the triphenyl-phosphonium and triphenylarsonium 2,3,4-triphonyloyolopenta-dienylides have been done and the properties and nucleophilioity of these ylides have been investigated. A comparison has also been drawn between these ylides and their totmaphenylcyclopenta-dienylide analogues.

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