A route to <i>C</i>-glycosides and <i>C</i>-disaccharides with functionalised linkages has been investigated. This convergent strategy involves cycloaddition of selected alkenes and sugar derived nitrile oxide moieties. The resultant 2-isoxazolines can be modified and subsequently ring opened to afford compounds with carbonyl or amino containing linkages. The alkenes selected for study were two w-unsaturated monosaccharide derivatives: 5,6-dideoxy-1,2-<i>O</i>-isopropylidene-a-D-<i>xylo</i>-hex-5-enofuranose and methyl 5,6-dideoxy-2,3-<i>O</i>-isopropylidene-a-D-<i>lyxo</i>-hex-5-enofuranoside. Styrene, oct-1-ene and methylenecyclohexane were also studied as models. Four sugar based nitrile oxides were investigated in cycloadditions to these alkenes, based on D-glucose, D-galactose, D-mannose and L-fucose. Three complementary cycloaddition procedures were developed and evaluated: the dehydration of 2,6-anhydro-1-deoxy-1-nitroalditols, the hypochlorite-mediated oxidative dehydrogenation of pyranosyl oximes, and the dehydrochlorination of a pyranosyl hydroximoyl chloride. The oximes and hydroximoyl chloride compounds were synthesised from the corresponding pyranosylnitromethanes. Reactions involving the sugar oximes typically resulted in variable yields of the by-product furazan N-oxide (furoxan) in addition to the cycloadducts, depending on the dipolarophile reactivity. In contrast, uniformly high yields of cycloadducts (70-90%) were obtained from the nitromethyl compounds and hydroximoyl chloride with a range of dipolarophiles; little or no nitrile oxide dimerisation was observed in these reactions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:657301 |
| Date | January 2000 |
| Creators | March, Andrew Ronald |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12565 |
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