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Picolinyl-assisted approaches to stereocontrolled glycosylation.

机译：吡啶甲酰基辅助的立体控制糖基化方法。

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摘要

Although carbohydrates are the most abundant molecules on Earth, our current knowledge of these fascinating natural compounds is still limited. Some aspects that are already known include the carbohydrate involvement in damaging cellular processes such as bacterial and viral infections, development of tumors, metastasis, septic shock, etc. Consequently the development of effective methods for the synthesis, isolation, analysis, and investigation of complex carbohydrates has become critical in all areas of glycoscience. Among various focus areas, stereocontrolled glycosylation has emerged as a topic of particular importance. Yet, it remains a remarkable challenge to chemists because a new chirality center is formed during glycosylation. A failure to control the stereoselectivity of glycosylation reactions will typically lead to mixtures of 1,2-cis and 1,2-trans diastereomers. The aim of stereocontrolling of glycosylation has been approached in a variety of ways and the effect of a neighboring acyl participating group has been among the most powerful stereodirecting factors known to date for obtaining 1,2-trans glycosides.;The work presented herein is dedicated to broadening the scope of the stereodirected glycosylation using the concept of participating groups. Novel to this approach is the development of a well-rounded methodology that allows for synthesizing either 1,2-cis or 1,2-trans glycosides by simple switching of protecting groups. This is accomplished via novel glycosyl donors equipped either with picolinyl (2-pyridylmethyl ether) or picoloyl (2-pyridylcarbonyl ester) groups. A mechanistic understanding of various modes of action of these groups enhanced our ability to perform stereodirected glycosylations with exceptional stereoselectivity. This led to the development of a novel concept to stereocontrolled glycosylation that we named Hydrogen-bond-mediated Aglycone Delivery (HAD). The HAD concept has been extended to the synthesis of various linear and branched oligosaccharides and broadening of all aspects of the methodology. Furthermore, this study evolved into the development of a new type of glycosyl donors allowing for switchable stereoselectivity.
机译：尽管碳水化合物是地球上最丰富的分子，但我们目前对这些迷人的天然化合物的了解仍然有限。已经知道的一些方面包括碳水化合物参与破坏细胞过程的过程，例如细菌和病毒感染，肿瘤的发展，转移，败血性休克等。因此，开发了用于合成，分离，分析和研究复合物的有效方法。碳水化合物在糖科学的所有领域都变得至关重要。在各个重点领域中，立体控制糖基化已经成为特别重要的话题。然而，由于在糖基化过程中形成了新的手性中心，这对化学家仍然是一个巨大的挑战。无法控制糖基化反应的立体选择性通常会导致1,2-顺式和1,2-反式非对映异构体的混合物。已经以多种方式达到了立体控制糖基化的目的，并且相邻的酰基参与基团的作用已经成为迄今为止已知的最强的立体定向因子，用于获得1,2-反式糖苷。使用参与基团的概念来拓宽立体定向糖基化的范围。这种方法的新颖之处在于开发了一种全面的方法，该方法可通过简单切换保护基来合成1,2-顺式或1,2-反式糖苷。这是通过配备有吡啶甲基（2-吡啶基甲基醚）或吡啶甲基（2-吡啶基羰基酯）基团的新型糖基供体来实现的。对这些基团的各种作用方式的机械理解增强了我们以优异的立体选择性进行立体定向糖基化的能力。这导致了立体控制糖基化的新概念的发展，我们将其命名为氢键介导的糖苷配基递送（HAD）。 HAD概念已扩展到各种线性和分支寡糖的合成，并扩展了方法学的所有方面。此外，该研究发展成为新型糖基供体的开发，其可切换的立体选择性。

著录项

  • 作者

    Yasomanee, Jagodige P.;

  • 作者单位

    University of Missouri - Saint Louis.;

  • 授予单位 University of Missouri - Saint Louis.;
  • 学科 Organic chemistry.;Chemistry.;Biochemistry.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 269 p.
  • 总页数 269
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 土壤学;
  • 关键词

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