Organic Synthesis Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok 10330, Thailand.
Green Chemistry for Fine Chemical Productions STAR, Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok 10330, Thailand.
Org Biomol Chem. 2021 Jan 28;19(4):822-836. doi: 10.1039/d0ob02246b. Epub 2021 Jan 6.
Thioglycosides are an important class of sugars, since they can be used as non-ionic biosurfactants, biomimetic glycosides, and building blocks for carbohydrate synthesis. Previously, Brønsted- or Lewis-acid-catalyzed dehydrative glycosylations between a 1-hydroxy sugar and a thiol have been reported to yield open-chain dithioacetal sugars as the major products instead of the desired thioglycosides. These dithioacetal sugars are by-products derived from the endocyclic bond cleavage of the thioglycosides. Herein, we report dehydrative glycosylation in water mediated by a Brønsted acid-surfactant combined catalyst (BASC). Glycosylations between 1-hydroxy furanosyl/pyranosyl sugars and primary, secondary, and tertiary aliphatic/aromatic thiols in the presence of dodecyl benzenesulfonic acid (DBSA) provided the thioglycoside products in moderate to good yields. Microwave irradiation led to improvements in the yields and a shortening of the reaction time. Remarkably, open-chain dithioacetal sugars were not detected in the DBSA-mediated glycosylations in water. This method is a simple, convenient, and rapid approach to produce a library of thioglycosides without the requirement of anhydrous conditions. Moreover, this work also provides an excellent example of complementary reactivity profiles of glycosylation in organic solvents and water.
硫代糖苷是一类重要的糖，因为它们可用作非离子型生物表面活性剂、模拟糖苷和碳水化合物合成的构建块。此前，已有报道称，在 1-羟基糖和硫醇之间，通过 Brønsted 酸或路易斯酸催化的脱水糖基化反应，主要生成开链二硫缩醛糖，而不是所需的硫代糖苷。这些二硫缩醛糖是硫代糖苷中环内键断裂的副产物。在此，我们报告了由 Brønsted 酸-表面活性剂组合催化剂 (BASC) 在水中介导的脱水糖基化反应。在十二烷基苯磺酸 (DBSA) 的存在下，1-羟基呋喃糖/吡喃糖与伯、仲和叔脂肪族/芳族硫醇之间的糖苷化反应以中等至良好的产率得到了硫代糖苷产物。微波辐射提高了产率并缩短了反应时间。值得注意的是，在 DBSA 介导的水中糖苷化反应中未检测到开链二硫缩醛糖。该方法是一种简单、方便、快速的方法，可在无需无水条件下制备硫代糖苷文库。此外，这项工作还为有机溶剂和水中糖苷化反应互补反应性的研究提供了一个很好的范例。
