Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 12 of 12 for “"Hemiacetal"”.
-
Sulfoxide Catalyzed Dehydrative Glycosylation. Reaction Development and Mechanistic Analysis
… glycosylation for the coupling of carbohydrate hemiacetals and nucleophilic alcohols has been developed. In this procedure, a glycosyl hemiacetal is treated with the reagent combination of benzenesulfonic anhydride and a substoichiometric amount of n-butyl sulfoxide, followed by the addition of …
-
Development and Investigation of a Dehydrative Glycosylation With Activated Diphenyl Sulfonium Reagents
… activated via nucleophilic attack of the hemiacetal hydroxyl upon the sulfonium center of diphenylsulfide bis(trifluoromethanesulfonate), leading to formation of a glycosyl oxosulfonium. Low temperature NMR studies have revealed that a glycosyl pyridiniurn is subsequently formed in the …
-
Structural characterisation and absolute stereochemistry of some degraded carotenoids from New Zealand honeys
… study (MacroModel) of the diastereoisomeric hemiacetal MPA esters. The results of the determination, coupled with a consideration of crystallographically-determined hemiacetal ester conformations obtained from a search of the Cambridge Structural Database, supported the use of the …
-
I. Chemoselective Dehydrative Glycosylation With Application Toward Oligosaccharide Synthesis. II. Sulfide-Mediated Direct Glycosylation of C(1)-Hydroxyl Glycosyl Donors. III. Studies Toward the Total Synthesis of Auriside A
… in the third part of the dissertation. The hemiacetal disaccharide portion of auriside A is successfully synthesized. The convergent synthesis of the auriside aglycon component is accomplished in 17 linear steps using the Mukaiyama aldol reaction, the intramolecular Mitsunobu …
-
Entwicklung einer modularen Synthese chimärer Makrolidantibiotika aus Zuckern
… die intramolekulare WITTIG-Olefinierung eines ω-Hemiacetal-Phosphoniumylids geschlossen werden. Die Vorstufe sollte dabei aus zwei Building-Blocks aufgebaut werden, einem Zuckerbaustein und einem Spacer. Zur Darstellung des Zuckerbausteins wurde von Cellulose ausgegangen, welche um eine …
-
Total Synthesis of the Actinoallolides and a Designed Photoaffinity Probe for Target Identification
… installation of the labile transannular hemiacetal motif. Late-stage diversi cation then provides ready access to the congeneric (+)-actinoallolides B-E. The unknown mechanism of action of the actinoallolides poses a barrier to their potential utilisation as lead compounds for drug …
-
Understanding the mechanism of androgen biosynthesis
… state permitted identification of a new peroxo hemiacetal intermediate species initiated by nuclophilic attack on the substrate molecule by the peroxoanion. As a whole, this work details the structural and functional properties of CYP17A1 active in human androgen biosynthesis.
-
Resonance Raman spectroscopy in the analysis of residual lignin and other unsaturated structures in chemical pulps
… that part of the carbonyls exist in hydrate, hemiacetal and/or hemiketal forms. It was also shown that these structures interconvert upon drying and wetting of the pulps. UVRRS was efficient in detecting extremely low contents of carbonyls, unlike IR spectroscopy, which did not detect any …
-
Part I. Rhodium-catalyzed asymmetric functionalization of allylic amines Part II. Harnessing kinetic driving forces in alkyne metathesis for the synthesis of complex molecular architectures
… water leads to the formation of a hemiaminal or hemiacetal depending on the nucleophile. The hydrogen on the methine carbon in the resulting intermediate is hydridic in nature. We hypothesized that the Rh(I) catalyst could perform a dual role in the reaction where after the allylic isomerization, …
-
Synthesis of Polysaccharide Aldehydes or Ketones and Fabrication of Derived Hydrogels or Microgels
… is in equilibrium between a ring-closed hemiacetal and an open-chain aldehyde form, we developed a novel method to prepare polysaccharide aldehydes by attaching monosaccharides to polysaccharide chains. Herein, we describe the approach of attachment through amination between amine group …
-
Catalytic routes for oxygenate conversion on solid acids and supported metal nanoparticles
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-12-01
-
Synthesis and Characterization of a Novel Polyacetal & Design and Preparation of Superhydrophobic Photocatalytic Surfaces
… of co-monomer units. By interrupting the facile hemiacetal hydrolysis reaction that can propagate along the macromolecular chain, these co-units function as a "stopper" against degradation of the main block, -(CH<sub>2</sub>O)<sub>n</sub>-. The copolymer can also be blended with additives such as …