糖醛及其衍生物与四嗪的逆电子需求 Diels-Alder 反应。
Inverse-electron demand Diels Alder Reactions between glycals and tetrazines.
机构信息
Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Ave., South Orange, NJ, 07079, USA.
Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Ave., South Orange, NJ, 07079, USA; Center for Computational Research, Seton Hall University, South Orange, NJ, 07079, USA.
出版信息
Carbohydr Res. 2022 Sep;519:108623. doi: 10.1016/j.carres.2022.108623. Epub 2022 Jun 17.
The inverse-electron demand Diels Alder reaction (IEDDA) of substituted tetrazines with 2,3-unsaturated sugars (glycals) has been investigated to prepare novel carbohydrate-based heterocycles. The cycloaddition reactions occurred in moderate to good, isolated yields and gave acyclic, C-linked pyranose diazines as the major products (33-90%). The effects of variations in sugars, sugar protecting groups, and reaction solvents on the yields and products obtained in these reactions were studied. Lower yields of adducts were isolated for TBDMS-protected glucals and for 4,6-O-benzylidene protected glucals. When unprotected sugars were used, the reactions failed to give the desired cycloadducts. A range of substituted tetrazines were also evaluated in these reactions. For comparison, HOMO-[LUMO + 1] gaps for glycal-tetrazine pairs were calculated using Density Functional (DFT) calculations at the B3LYP/631G+ level.
已研究取代的四嗪与 2,3-不饱和糖（糖醛）的反电子需求 Diels-Alder 反应（IEDDA），以制备新型基于碳水化合物的杂环。环加成反应以中等至良好的分离产率发生，并得到非循环的、C 连接的吡喃糖二嗪作为主要产物（33-90%）。研究了糖、糖保护基和反应溶剂的变化对这些反应中获得的产率和产物的影响。TBDMS 保护的葡萄糖醛和 4,6-O-亚苄基保护的葡萄糖醛的加合物收率较低。当使用未保护的糖时，反应未能得到所需的环加成物。还评估了一系列取代的四嗪在这些反应中的作用。为了进行比较，使用密度泛函（DFT）计算在 B3LYP/631G+水平上计算了糖醛-四嗪对的 HOMO-[LUMO+1]间隙。
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