Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA.
Chemistry. 2021 Jan 4;27(1):354-361. doi: 10.1002/chem.202003479. Epub 2020 Nov 30.
Our group has previously reported that 3,3-difluoroxindole (HOFox) is able to mediate glycosylations via intermediacy of OFox imidates. Thioglycoside precursors were first converted into the corresponding glycosyl bromides that were then converted into the OFox imidates in the presence of Ag O followed by the activation with catalytic Lewis acid in a regenerative fashion. Reported herein is a direct conversion of thioglycosides via the regenerative approach that bypasses the intermediacy of bromides and eliminates the need for heavy-metal-based promoters. The direct regenerative activation of thioglycosides is achieved under neutral reaction conditions using only 1 equiv. NIS and catalytic HOFox without the acidic additives.
我们小组之前曾报道过，3,3-二氟代吲哚啉（HOFox）可以通过 OFox 亚氨酸酯中间体介导糖苷化反应。首先，硫代糖苷前体被转化为相应的糖苷溴化物，然后在 AgO 的存在下转化为 OFox 亚氨酸酯，随后以再生的方式用催化路易斯酸进行激活。本文报道了一种直接通过再生方法转化硫代糖苷的方法，该方法绕过了溴化物中间体，并且不需要使用重金属基促进剂。在仅使用 1 当量 NIS 和催化 HOFox 且没有酸性添加剂的情况下，在中性反应条件下即可实现硫代糖苷的直接再生激活。
