1,2-Dioxines are a specific class of cyclic peroxide that are both prevalent in nature and important synthetic building blocks. To date, much of the chemistry involving 1,2-dioxines is concerned with cleavage of the weak peroxide bond, providing a convenient method for the incorporation of 1,4-oxygen functionality into molecules. Comparatively little attention has been directed towards transformations of the alkene unit contained within 1,2-dioxines, which is the focus of this thesis. The synthesis of a broad range of diversely functionalised 1,2-dioxines from commonly available starting materials is presented. Subsequently, the osmium catalysed dihydroxylation of 3,6-disubstituted 1,2-dioxines was investigated, furnishing novel peroxy diols in high yield and with excellent diastereoselectivity. The peroxy diols were then reduced, affording stereospecific tetraols and higher polyols, including the rare sugar allitol. In addition, homolytic ring-opening of the 1,2-dioxanes was examined, providing a new route to polyhydroxylated furanoses, highlighted by the synthesis of the natural keto-sugar psicose. Several 4-substituted 1,2-dioxines were also dihydroxylated, followed by reduction of the peroxide bond, providing a convenient route to branched erythritol derivatives, including the important plant sugar 2-C-methyl-erythritol. The cobalt catalysed ring-opening of the peroxy diols produced novel erythrose derivatives in high yield. In addition, the triphenylphosphine induced ring contraction of the peroxy diols is presented, which allowed for the synthesis of novel dihydroxylated tetrahydrofurans in excellent yield. Asymmetric dihydroxylation of the achiral 4-substituted 1,2-dioxines was explored, furnishing optically enriched peroxy diols with varying enantioselectivity depending on the substrate. The synthesis of novel alkyl and aryl branched erythrono-γ-lactones via oxidation of lactols derived from the acetonide protected peroxy diols is also documented. The utility of this sequence is illustrated by the preparation of potassium 2,3,4-trihydroxy-2-methylbutanoate, a leaf-closing substance of Leucaena leucocephalam. Additionally, γ-lactones were prepared from epoxy hydroxy ketones derived from epoxy-1,2-dioxanes, facilitated by a Baeyer-Villiger lactonisation protocol. The requirements and limitations of this procedure are discussed. The proposed and attempted synthesis of other lactones from 1,2-dioxines was also examined. Finally, several other general alkene transformations were investigated on 1,2- dioxines including: halo-hydrin formation, phenylselenyl chloride addition, aminohydroxylation, cyclopropanation, and aziridination, allowing for the preparation of several new classes of functionalised 1,2-dioxines. In summary, the work presented in this thesis establishes clear and efficient methodology towards several interesting and useful sugar-type core structures from modified 1,2-dioxines. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1313493 / Thesis (Ph.D) -- University of Adelaide, School of Chemistry and Physics, 2008
| Identifer | oai:union.ndltd.org:ADTP/264482 |
| Date | January 2008 |
| Creators | Robinson, Antony Vincent |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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