Many aspects of the desulfurization of trisulfides have been investigated. Efforts directed toward the syntheses of cyclic trisulfides provided mixtures of oligomers or the corresponding disulfide. Radiochemically labelled trisulfides and an optically active trisulfide have been desulfurized by a variety of phosphines. Triarylphosphines preferentially removed the central sulfur atom under all conditions, while tris(dialkylamino)phosphines exhibited preferential terminal sulfur removal in low polarity solvent with a trend to increased central sulfur removal with increased solvent polarity. Exchange phenomena were examined and a mechanistic rationalization presented. Desulfurization by triarylphosphines was concluded to proceed by the rate-determining decomposition of a phosphonium salt to form products, while desulfurization by tris(dialkylamino)phosphines was considered to have phosphonium salt formation as the rate-determining step. / The reaction of trisulfides with trialkyl phosphites to give a mixture of unsymmetrical and symmetrical disulfides has been studied. Mechanistic and synthetic aspects are described. / The spontaneous desulfurization of sulfenic sulfonic thioanhydrides and exchange of the thiosulfonate products in polar solvents were examined.

A general route to optically active organosulfur and phosphorus compounds was investigated. Sulfinimides incorporating camphorimide were synthesized directly from a sulfinyl chloride and N-(trimethylsilyl)camphorimide. The diastereomers were found to be inseparable by crystallization or chromatography, although in one case an optically active sulfinamide was prepared by an asymmetric synthesis. / The phosphorus-imide bond was formed by coupling of an asymmetric phosphinous chloride and N-(trimethylsilyl)camphorimide. Addition of sulfur gave N-(phosphinothioyl)camphorimides as separable diastereomers. These were converted into optically active thiophosphoryl compounds which were chiral only at phosphorus. The absolute configurations of the diastereomers were obtained by single-crystal X-ray analysis, through NMR techniques and by conversion into phosphinothioic acids. / Displacement of camphorimide was effected with organometallic reagents, alcohols and thiols to give optically active phosphine sulfides, phosphinothionates and phosphinodithioates respectively. Optical yields of the products were dependant on the reagents and reaction conditions used. Mechanistic rationales are presented to account for the stereochemical results.

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Thesis (Ph. D.)--Lehigh University, 2005. / Includes vita. Includes bibliographical references.

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

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Organosulfur plays a significant role in synthetic chemistry. In particular α,β-unsaturated sulfides (i.e. vinyl sulfides) are versatile building blocks that exhibit untapped potential in reaction development. This thesis focuses on reaction development in this space. Chapter 1 discusses the characteristics that sulfur attributes to organic molecules followed by a review of synthetic preparations and applications of vinyl sulfides. Chapter 2 discusses the development of a formal-phosphorus Pummerer reaction enabling simple access to thiophosphonium Wittig reagents. These thiophosphonium salts are used to access a library of vinyl sulfide substrates that are further hydrolyzed to the corresponding ketones. This two-step sequence enables a strategic approach affording aldehyde to ketone homologation via vinyl sulfide intermediates, enabling access to synthetically challenging α-aryl ketones. Chapter 3 discusses the direct use of vinyl sulfides as carbonyl surrogates in Fischer indole reactions. Vinyl sulfides are demonstrated to be aldehyde and ketone surrogates in the preparation of diverse 3-substituted and 2,3-disubstituted indoles or azaindoles. The utility of this chemistry is shown with the preparations of three biologically significant compounds: 4-aza-melatonin, a furoindoline scaffold and an indomethan-like CRTh2 anatagonist. Chapter 4 showcases the first total synthesis of a chromane natural product isolated from Cassia fistula: 1-(3,4-dihydro-5-meth- oxy-2,2-dimethyl-2H-chromen-7-yl)propan-2-one. The preparatory route of this natural product features two synthetic methods developed by the Magolan group, including the aldehyde to ketone homologation described in Chapter 2. The five-step total synthesis affords the natural product in 24% overall yield and includes an efficient one-pot three-transformation sequence. Chapter 5 highlights ongoing and future projects that build on the research described in this thesis. This includes investigations into stable intermediates that facilitate access to aldehydes from vinyl sulfides. Plans are proposed to develop controlled stereoselective use of thiophosphonium reagents. Further collaborative work is discussed employing vinyl sulfides as substrates for valuable atropoisomeric heterocyclic scaffolds. / Thesis / Doctor of Philosophy (PhD)

This research has been directed at the study of neighboring group participation in electrooxidation of thioethers. Controlled potential oxidation of substituted 1,3-dithiane in wet acetonitrile provides substituted 1,2-dithiolane 1-oxide in good yield. Thioethers appended with neighboring alcohols and carboxylate are catalytically oxidized in a redox cycle by bromide ion. The formation of the alkoxysulfonium salt intermediates in such reactions is confirmed by product study. On the other hand, the acyloxysulfonium salt intermediates in the electrooxidation of endo -6-methylthio-bicyclo [2.2.1] heptane-2- endo -carboxylic acid (1) are unstable at room temperature. Control experiments using ¹⁸O labeled compounds prove unequivocally the existent of the acyloxysulfonium salt intermediates. Diastereospecific oxidation of 1 and its methyl ester with DABCO.2Br₂ complex and m-CPBA is sterically controlled. In both cases, similar product ratios are observed which is explained by the participation of the carboxylic acid group in the case of DABCO.2Br₂ oxidation but not in the case of m-CPBA oxidation. The structure of one of the diastereomer of the endo acid sulfoxide is unequivocally proved by x-ray crystallographic analysis.