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dc.contributor.advisorMajewski, Mareken_US
dc.creatorPalyam, Nagarjunaen_US
dc.date.accessioned2010-06-30T23:41:23Zen_US
dc.date.accessioned2013-01-04T04:41:26Z
dc.date.available2011-12-28T08:00:00Zen_US
dc.date.available2013-01-04T04:41:26Z
dc.date.created2010-06en_US
dc.date.issued2010-06-28en_US
dc.date.submittedJune 2010en_US
dc.identifier.urihttp://hdl.handle.net/10388/etd-06302010-234123en_US
dc.description.abstractDioxanones (1) are ketal- or acetal protected forms of 1,3-dihydroxyacetone (DHA). The thesis presents the stereoselective aldol transformations of dioxanones and applications to the synthesis of natural and higher carbohydrates listed in Scheme 1. The field of organocatalysis has recently gained much popularity among the chemical research community. In our group, a set of conditions are developed to perform stereoselective aldol reactions on dioxanone substrate. Cs-symmetrical dioxanones have superior diasteroselectivities than C2v-symmetrical dioxanones (de up to 88% from 34%) and presence of mild Lewis acid (LiCl) or Brønsted acid additives (PyPTS) enhance the enantioselectivity into synthetically useful ranges (from 60 up to 96 % ee). The first aldol addition of dioxanone (1) to desired aldehydes (possessing masked carbonyl functionality), followed by reduction of the corresponding aldol adduct and upon unmasking the aldehyde functionality (i.e dithiane or dimethoxy acetal hydrolysis) resulted in furanose (II) and pyranose (III) forms of D-ribose. A new protocol was developed for the synthesis of biologically important deoxyiminosugars such as L-1-deoxymannojirimycin (DMJ, IV), L-1-deoxyidonojirimycin (DIJ, V) and N-isopropyl DIJ (IV) from readily available dioxanone (1) precursor. The key steps include diastereoselective proline-catalyzed syn-aldol transformation and a reductive amination / cyclization. D-glycero-D-manno-2-octulose (VII), a higher-carbon sugar isolated from opium poppies has been synthesized in enantiomerically pure form. The short synthetic sequence involved two proline-catalyzed aldol addition reactions of dioxanone (1) to appropriate aldehydes. Here, we developed a complete dioxanone methodology towards the higher monosaccharide in a stereocontrolled fashion. The enantioselective stereodivergent first total synthesis of DD- and LL-glycero-β-alloheptopyranose (IX, ent-IX) was accomplished from readily available non-chiral starting materials. The short synthetic sequence involves enamine and enolate mediated aldol reactions at α and α' positions of dioxanone (1) hence demonstrated the complementary nature of organocatalysis and organometallic methods.en_US
dc.language.isoen_USen_US
dc.subjectprolineen_US
dc.subjectaldol reactionsen_US
dc.subjectDioxanoneen_US
dc.subjectcarbohydrates and higher monosaccharidesen_US
dc.titleSynthesis of higher carbohydrates and iminosugars on dioxanone scaffolden_US
thesis.degree.departmentChemistryen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophy (Ph.D.)en_US
dc.type.materialtexten_US
dc.type.genreThesisen_US
dc.contributor.committeeMemberSawicki, Grzegorzen_US
dc.contributor.committeeMemberPedras, Soledadeen_US
dc.contributor.committeeMemberSanders, David A. R.en_US
dc.contributor.committeeMemberPalmer, Daviden_US
dc.contributor.committeeMemberGreen, James R.en_US


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