Graduate Thesis Or Dissertation

 

New Methods in Carbohydrate Chemistry: Dehydrative Glycosylation with Cyclic Phosphonium Anhydrides and α-Selective Glycosylation of Glycosyl Phosphinites Public Deposited

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https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/mc87pq637
Abstract
  • Achieving a high level of efficiency in carbohydrate synthesis is dependent upon reactions that can provide high yields and stereoselectivity at the anomeric position. The nature of the glycosidic bond as either α or β configuration poses the greatest obstacle. The development of methods to control this inherent feature while also giving high yields is a primary goal for the field of carbohydrate chemistry. This thesis examines the potential for two new methods to overcome these challenges: dehydrative glycosylation with cyclic phosphonium anhydrides and glycosylation of glycosyl phosphinites. A collection of cyclic phosphonium anhydrides were prepared and tested with a range of glycosylation substrates. These glycosylations demonstrated good yield and selectivities for a number of examples and represent a new and practical type of dehydrative glycosylation. A number of 1D and 2D NMR experiments were carried out to better understand the mechanistic nature of this reaction. A collection of glycosyl phosphinites were also prepared and evaluated in their potential to give highly α-selective glycosylations through in situ anomerization. This method was used with a number of substrates giving good yield and high selectivities. The high α-selectivity of this method was explored through a number of 31P NMR experiments.
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  • 2016
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  • 2019-11-18
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