The interactions of singlet oxygen with 1-vinylcycloalkenes after P(OEt)(,3) reduction led to 1,2-dioxins 1 via 1,4-cycloaddition, secondary diene alcohols 3 by the "ene" reaction pathway and trans- and cis-1,2-dioxin alcohols 4 and 5 by further 1,4-cycloaddition of ('1)O(,2) to 3. Small amounts of competitive "ene" reaction product, the tertiary diene alcohols 2, were obtained only in the case of medium size rings (n = 9, 10 and 12). The stereochemistry of the various products was elucidated by NMR spectrometry. The product ratios showed that five and seven membered ring semicyclic dienes undergo predominantly the "ene" reaction. As ring size increases, 1,4-cycloaddition competes closely with the "ene" process, the crossover point being at ring size ten. The six membered ring semicyclic diene was an exception, 1,4-cycloaddition for this compound surpassing the "ene" reaction. The above results held also when 1-isopropenylcycloalkenes were used as substrates. Possible explanations in terms of the conformations of the alicyclic rings are presented. The predominant formation of secondary diene alcohols (Markovnikov directive effect) in the "ene" reaction process excluded the participation of a concerted ene mechanism involved in the semicyclic 1,3-diene systems. / The 1,2-dioxins and 1,2-dioxin alcohols (except those derived from five membered semicyclic dienes) were converted to furans on treatment with FeSO(,4) and successful syntheses of (R)-menthofuran, (R)-evodone and ((+OR-)) chromolaenin were accomplished. Thus, the ('1)O(,2)-FeSO(,4) sequence for the transformation of semicyclic 1,3-dienes into cyclic furanoterpenoids may indeed have biogenetic significance. / Source: Dissertation Abstracts International, Volume: 45-04, Section: B, page: 1196. / Thesis (Ph.D.)--The Florida State University, 1984.

The mechanism of the photochemical formation of tricyclo{6.4.0.0('2,7)}7,8-cis-dodec-1-ene (CB), 1'-methoxybicyclohex-1-ene (1,2 ET), and a new product, 2'-methoxybicyclohex-1-ene (1,4ET), from the sensitized irradiation of 1,1-bicyclohexenyl (BCH) in methanol has been investigated using steady state kinetic techniques. The effects of added acid, sensitizer energy, methanol concentration, BCH concentration, and temperature on the product quantum yields were evaluated. The solvent deuterium isotope effect on the product quantum yields was measured. Correlation of the steady state results with transient absorption flash spectroscopic measurements performed in collaboration with R. Bonneau (University of Bordeux, France) has provided proof that the intermediate responsible for all of the observed photochemistry is a strained ground state twisted transoid isomer of BCH, c,t-BCH, formed from the BCH triplet state. Reaction of c,t-BCH with methanol gives the methyl ethers, 1,2 ET and 1,4 ET. Cyclobutene (CB) formation occurs by a conrotatory electrocyclization of c,t-BCH. / The mechanism of photoproduct formation from the direct irradiation of BCH has also been investigated. The observed photoproducts are CB, 1,2 ET, 1,4 ET and 1,3'-bicyclohexenyl (UD). Steady state photochemical measurements of product quantum yields provide evidence that methanol addition to c,t-BCH formed from a BCH excited singlet state accounts for all of the observed ether formation. A reaction pathway to CB independent of c,t-BCH accounts for 36% of the observed CB formation. The formation of UD is consistent with its production from a BCH excited singlet state. The effects of changing the excitation wavelength on the CB/UD product ratio is discussed on the basis of ground state s-cis - s-trans conformational control of the photochemistry. / Source: Dissertation Abstracts International, Volume: 45-06, Section: B, page: 1780. / Thesis (Ph.D.)--The Florida State University, 1984.

Part one describes a systematic study of the diastereoselectivity of the kinetic Michael addition of ester, ketone and amide enolates to $\alpha$-(sulfinyl)butenolides. Numerous examples of high facial selectivity of $\alpha$-(t-butylsulfinyl)butenolide towards enolates have been discovered, and the factors that influence this selectivity were examined. The structure of the major adduct of the Michael addition of the lithium enolate of methyl acetate to $\alpha$-(t-butylsulfinyl)butenolide was solved by single crystal X-ray crystallography. The results indicate that the facial selectivity of $\alpha$-(sulfinyl)butenolides is determined by the orientation and the size of the sulfinyl group. The sulfur-oxygen bond of the sulfinyl group is antiperiplanar to the carbonyl group of the butenolide in the transition state. / Part two describes an efficient partial synthesis of the antitumor drug taxol. The synthetic equivalent of the taxol side chain precursor, optically pure (+)-3(R)-hydroxy-4(S)-phenyl-2-azetidinone, was obtained via either chemical resolution of racemic $\beta$-lactam or by an efficient asymmetric synthesis from the readily available and recyclable chiral auxiliary 4(R)-phenyloxazolidone. The first example of formation and reaction of a lithium enolate in dichloromethane solvent was discovered. The identity and stability of lithium hexamethyldisilazide in dichloromethane, as well as the reactivity of n-butyllithium in dichloromethane, were examined. N-Benzoyl-$\beta$-lactams were found to undergo DMAP-catalyzed rearrangement to oxazinone. In the presence of DMAP, N-benzoyl-3(R)-(1-ethoxyethoxy)-4(S)-phenyl-2-azetidinone and the corresponding oxazinone reacted with 7-TES-baccatin III to give, after deprotection, a high yield of taxol. / Source: Dissertation Abstracts International, Volume: 54-12, Section: B, page: 6209. / Major Professor: Robert A. Holton. / Thesis (Ph.D.)--The Florida State University, 1991.

The Kamlet-Taft solvatoohromic comparison method has been used to characterize the dipolarity/polarizability ((pi)*) and hydrogen-bond accepting basicity ((beta)) of supercritical carbon dioxide at various densities. The fluid medium is shown to be less polar (and/or polarizable) than cyclohexane by the (pi)* parameter. As the density of the medium is decreased the (pi)* parameter decreases on a smooth curve toward the gas phase value of (pi)*. Variation between the gas phase value of (pi)* and the value of (pi)* in supercritical carbon dioxide at different densities is quantitatively accounted for by a function of the refractive index which has been shown to be directly proportional to the dispersion force contribution to the free energy of interaction in solution. / The solvatochromism of the internal charge transfer absorption band of 4-diethylamino-4'-nitroazobenzene, DENAB, correlates linearly with the (pi)* parameter in conventional solvents and in supercritical carbon dioxide at various densities. The free energy of activation, (DELTA)G('(tau)), for the thermal cis to trans relaxation of DENAB correlates roughly with (pi)* in conventional solvents, however, this same correlation fails to continue in supercritical carbon dioxide. A correlation between (DELTA)G('(tau)) and (pi)* is found in supercritical carbon dioxide and two conventional non-polar solvents. This correlation has a much smaller slope than the rough correlation found in conventional polar aprotic solvents, and is of opposite sign. The change in behavior of (DELTA)G('(tau)) as a function of (pi)* is interpreted as indication a change of mechanism on going from polar to non-polar solvents. / The decomposition of phenylazotriphenylmethane (PAT) has been studied in supercritical carbon dioxide. PAT gives a poor material balance upon decomposition even though the solvent does not appear to be reacting with the radical species formed during the decomposition. The observed rate of decomposition is intermediate to that in cyclohexane and the proposed "zero" viscosity rate. / The decompositions of two secondary diacyl peroxides have been studied in supercritical carbon dioxide, cyclobutanecarboxoyl- m-chlorobenzoyl peroxide and isobutyryl peroxide. Experiments with ('13)C labels in the acyl moiety of the peroxides show that an exchange of 13CO2 groups with carbon dioxide solvent molecules occurs during carboxy-inversion. (Abstract shortened with permission of author.) / Source: Dissertation Abstracts International, Volume: 48-02, Section: B, page: 0446. / Thesis (Ph.D.)--The Florida State University, 1986.

This work focuses on the development of new synthetic methods for the preparation of various N-heterocycles. While I have encountered many road blocks throughout my PhD, it has taught me how to solve a wide variety of challenges through perseverance, critical thinking and collaboration. I have successfully developed multiple projects stemming from my independent ideas for new chemical transformations. The projects range from cyclizations of o-alkenylisocyanides using a variety of radical precursors to C(sp3)-H amination (with and without transition metals) reactions. The discovery of selective addition of radicals to isonitriles could be harnessed to initiate a radical cascade that was designed to overcome the stereoelectronic restrictions on homoallylic ring expansion in alkyne reactions by using alkenes as synthetic equivalents of alkynes. This allowed us to establish a new route for N-heteroaromatics by coupling a homoallylic ring expansion with a stereoelectronically assisted C-C bond scission to yield the formal “6-endo” products. Additionally we have developed multiple protocols for C(sp3)-H aminations. Firstly, a transition metal mediated approach using FeCl3/DDQ for an intramolecular C(sp3)-H oxidative amination. In this reaction, an aniline group can activate the molecule for single-electron-transfer while also acting as an internal nucleophile to trap reactive intermediates. Following a consecutive electron transfer oxidation process, we can couple free amines with -CH2- groups to afford aromatic N-heterocycles using inexpensive reagents. Expansion of the intramolecular oxidative C(sp3)-H amination to unprotected anilines and amides and C(sp3)-H bonds to occur under mild conditions using t-BuOK, DMF and O2. This protocol relies on a synergy between base, radical and oxidizing species to promote a coordinated sequence of deprotonation followed by H-atom transfer and oxidation that constructs a new C-N bond. We were able to apply this chemistry to the preparation of a wide variety of N-heterocycles, ranging from small molecules to extended aromatics without the need for transition metals or strong oxidants. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2018. / April 13, 2018. / Development, Methodology, N-heterocycles, Organic, Reaction / Includes bibliographical references. / Igor V. Alabugin, Professor Directing Dissertation; Michael Blaber, University Representative; Kenneth Hanson, Committee Member; Justin Kennemur, Committee Member.

This dissertation discloses the work of several research projects involving stereoelectronic effects as a tool to control chemical reactivity. In particular, three areas have been discussed in details: 1. Taming oxygen-rich systems with stereoelectronic effects; 2. Au(I)-Catalyzed Bergman-Cyclization; 3. Isonitriles as stereoelectronic chameleons. Chapter One starts by introducing stereoelectronic effects. In this chapter, I explain how stereoelectronic effects can be studied computationally by defining the tools used throughout this dissertation with definitions and providing examples of their utility. The main quantitative tools for stereoelectronic effects are introduced: conformational changes, reaction equations (such as isodesmic equations), and Natural Bond Orbital (NBO) analysis. The concept of hyperconjugation is explained, with special attention to the role of polarity on the magnitude of these interactions. Chapter Two expands on the role of stereoelectronic effects as a tool to control chemical reactivity by showing examples of how oxygen-rich systems can be tamed. The unusual stability of bis-peroxides contradicts conventional wisdom – some of them can melt without decomposition at temperatures exceeding 100 oC. In this chapter, we disclose a stabilizing stereoelectronic effect that two peroxide groups can exert on each other. This stabilization originates from strong anomeric n_O→σ_(C-O)^* interactions that are absent in mono-peroxides, but reintroduced in molecules where two peroxide moieties are separated by a CH2 group. The two unstable peroxides are transformed into two acetals. The value of stereoelectronic guidelines is illustrated by the discovery of a convenient, ozone-free synthesis of bridged secondary ozonides from 1,5-dicarbonyl compounds and H2O2. The expected tetraoxanes are not formed when the structural distortions imposed on the tetraoxacyclohexane subunit by a three-carbon bridge partially deactivate the anomeric effects, a design projected from our computational endeavors. Finally, we have employed stereoelectronic effects to design a trap for the Criegee Intermediate (CI), the elusive intermediary for the Baeyer-Villiger reaction. Our strategy involved the deactivation of transition-state stabilizing effects for the migratory step via precise cyclic constraints and the usage of the newly-found reverse α-effect. Chapter Three explores the stereoelectronic and zwitterionic assistance in the Au(I)-Catalyzed Bergman Cyclization. With 90% of chemically individual molecules in nature containing a carbo- or heterocyclic subunit, the ability to make cyclic structures in an efficient and selective manner can be paramount to the success of a synthesis. Out of the three main approaches to the formation of cyclic structures (i.e., cyclizations, pericyclic reactions, and cycloaromatizations), cycloaromatization reactions are by far the most unusual and difficult to control. A typical cyclization reaction generally involves a "preformed" high energy reactive center (e.g., a cation, a radical, or an anion) that attacks a weak functionality (e.g., a π-bond) in a process where one bond is formed and the other is broken. In a similar way, the number of bonds is conserved in the classic pericyclic reactions which avoid the formation of unstable intermediates by coordinating the bond-breaking and the bond-forming processes. However, the synergy between bond formation and bond breaking that is typical for pericyclic reactions is lost in their mechanistic cousins, cycloaromatization reactions. In these reactions, exemplified by the Bergman cyclization (BC), two bonds are sacrificed to form a single bond and the reaction progress is interrupted at the stage of a cyclic diradical intermediate. Intrigued by a recent discovery of an unusually fast Au-catalyzed BC, we developed two key tools that allowed us to understand the nature of the catalytic effect: First, we developed a strategy to analyzed the intricate bonding aspects (via NBO analysis) of the two perpendicular π-systems through the course of the reaction; In parallel, we advanced a new theoretical framework for understanding the nature of the catalytic effect by applying the distortion-interaction (DI) analysis to metal-catalyzed reactions. Until then, the widely used DI model was only applied for bimolecular processes. We have shown that our model can provide useful information regarding unimolecular reactions promoted by coordination with a catalyst. Chapter Four dives into the chameleonic behavior of isonitriles facing reactions with radicals. Radical addition to isonitriles (isocyanides) starts and continues all the way to the TS mostly as a simple addition to a polarized pi-bond. Only after the TS has been passed, the spin density moves to the alpha-carbon to form the imidoyl radical, the hallmark intermediate of the 1,1-addition-mediated cascades. Addition of alkyl, aryl, heteroatom-substituted and heteroatom-centered radicals reveals a number of electronic, supramolecular, and conformational effects potentially useful for the practical control of isonitrile-mediated radical cascade transformations. Addition of alkyl radicals reveals two stereoelectronic preferences. First, the radical attack aligns the incipient C⋯C bond with the aromatic pi-system. Second, one of the C-H/C-C bonds at the radical carbon eclipses the isonitrile N-C bond. Combination of these stereoelectronic preferences with entropic penalty explains why the least exergonic reaction (addition of the t-Bu radical) is also the fastest. Heteroatomic radicals reveal further unusual trends. In particular, the Sn radical addition to the PhNC is much faster than addition of the other group IV radicals, despite forming the weakest bond. This combination of kinetic and thermodynamic properties is ideal for applications in control of radical reactivity via dynamic covalent chemistry and may be responsible for the historically broad utility of Sn-radicals ("the tyranny of tin"). In addition to polarity and low steric hindrance, radical attack at the relatively strong pi-bond of isonitriles is assisted by "chameleonic" supramolecular interactions of the radical center with both the isonitrile pi*-system and lone pair. These interactions are yet another manifestation of supramolecular control of radical chemistry. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2018. / November 6, 2018. / computational chemistry, Gold-catalyzed Bergman cyclization, isonitriles, organic chemistry, oxygen-rich systems, stereoelectronic effects / Includes bibliographical references. / Igor V. Alabugin, Professor Directing Dissertation; Bruce Locke, University Representative; Kenneth Hanson, Committee Member; James H. Frederich, Committee Member.

Source: Dissertation Abstracts International, Volume: 31-09, Section: B, page: 5276. / Thesis (Ph.D.)--The Florida State University, 1970.

Source: Dissertation Abstracts International, Volume: 32-04, Section: B, page: 2062. / Thesis (Ph.D.)--The Florida State University, 1971.

Source: Dissertation Abstracts International, Volume: 32-09, Section: B, page: 5107. / Thesis (Ph.D.)--The Florida State University, 1971.

Source: Dissertation Abstracts International, Volume: 30-02, Section: B, page: 0556. / Thesis (Ph.D.)--The Florida State University, 1968.