醣在自然界中分布廣泛，且在生活中扮演重要的角色，而有效控制醣鏈結的立體位向是醣化學中具挑戰性的議題。不同於以往的文獻，我們發現，醣鏈結反應中加入含有氯離子的促進劑會參與醣鏈結反應，反應過程中會形成醣基氯化物的中間產物，進而影響立體選擇性。 從本實驗室的研究發現，我們了解到醣基氯化物之中間產物的重要性。本篇論文主要探討二-去氧半乳醣在醣基氯化物的中間產物媒介下的醣鏈結反應之立體選擇性。我們先藉由低溫核磁共振光譜的幫助來進行醣基氯化物之中間產物的鑑定。我們並且另外在反應中加入不同種類的促進劑，或是不同種類的添加劑，探討其如何影響醣鏈結反應的立體選擇性。 ;Sugars are widely distributed in nature, and play important roles in living systems. Controlling the stereoselectivity in glycosylation reactions is a challenging issue in carbohydrate chemistry. Different from commonly believed in the literature, we have found that the chloride from the promoters actually participates into the glycosylation reactions, and the chloride- intermediates affects the stereoselectivity. From ours discovery, we understand the importance of the glycosyl-chloride intermediate. In this thesis, we focus on how the influence of 2-deoxygalactosyl chloride intermediates affects the stereoselectivity of their glycosylation reactions. We first identified the 2-deoxygalactosyl intermediates by NMR spectroscopy under low temperature. Furthermore, we added different types of promoters and additives in the reaction to investigate their effect to the stereoselectivity of the glycosylation reactions.
