Exploring Palladium Chemistry in Carbohydrate Synthesis

这项拟议的项目将集中于开发一种新的方法，直接从甘氨酸三羟乙酯立体选择性地合成α-2，3-不饱和-O-糖苷。这种方法只依赖于催化剂-甘氨酸络合的性质来控制异构体中心的立体选择性。将进行研究，以阐明该反应的机理。该方法将应用于长春霉素和1，2-顺式糖苷的全合成。本建议的第二个方面是开发一种有效的方法，通过钯(II)催化的甘氨酸三氯乙酸酯重排反应合成α-和β-糖基脲。将进行进一步阐明催化剂的性质以及重排机理的研究。凭借这一奖项，有机和高分子化学计划支持蒙大拿州立大学化学和生物化学系的阮海恩教授开发构建生物活性碳水化合物的有效方法。碳水化合物是自然界中结构最多样的一类生物分子，目前已确定它们在各种生物系统中的关键作用取决于低聚糖与其他大分子之间的特定相互作用。近年来，糖基尿素类药物的研究在氨基糖苷类抗生素领域得到了应用。

This proposed project will focus on the development of a new method for stereoselective synthesis of alpha-2,3-unsaturated-O-glycosides directly from glycal trichoroacetimidates. This approach relies only on the nature of the catalyst-glycal complexation to control the stereoselectivity at the anomeric center. Studies to elucidate the mechanism of this reaction will be undertaken. This method will be applied toward the total synthesis of vineomycin as well as 1,2-cis glycosides. The second aspect of this proposal is to develop an efficient method for the synthesis of alpha- and beta-glycosyl ureas via palladium(II)-catalyzed rearrangement of glycal trichloroacetimidates. Studies to further elucidate the nature of the catalysts as well as the mechanism of the rearrangement will be undertaken.With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Professor Hien Nguyen of the Department of Chemistry and Biochemistry at Montana State University to develop efficient methods for constructing biologically active carbohydrates. Carbohydrates are the most structurally diverse class of biomolecules in nature, and it is now established that their critical roles in a variety of biological systems depend on the specific interactions between oligosacharides and other macromolecules. The research on the area of glycosyl ureas has recently emerged with applications in the field of aminoglycoside antibiotics.