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Cyclodextrins are widely used as carriers of small molecules for drug delivery owing to their remarkable host properties and excellent biocompatibility. However, cyclic oligosaccharides with different sizes and shapes are limited. Cycloglycosylation of ultra‐large bifunctional saccharide precursors is challenging due to the constrained conformational spaces. Herein we report a promoter‐controlled cycloglycosylation approach for the synthesis of cyclic α‐(1→6)‐linked mannosides up to a 32‐mer. Cycloglycosylation of the bifunctional thioglycosides and (Z)‐ynenoates was found to be highly dependent on the promoters. In particular, a sufficient amount of a gold(I) complex played a key role in the proper preorganization of the ultra‐large cyclic transition state, providing a cyclic 32‐mer polymannoside, which represents the largest synthetic cyclic polysaccharide to date. NMR experiments and a computational study revealed that the cyclic 2‐mer, 4‐mer, 8‐mer, 16‐mer, and 32‐mer mannosides adopted different conformational states and shapes. [ABSTRACT FROM AUTHOR]

In their Research Article (e202307851), Peng Xu, Alba Silipo, You Yang et al. present a promoted-controlled cycloglycosylation approach for the synthesis of a series of cyclic mannosides up to a 32-mer. Keywords: Carbohydrates; Conformational Analysis; Cyclic Oligosaccharides; Cycloglycosylation; Glycosylation EN Carbohydrates Conformational Analysis Cyclic Oligosaccharides Cycloglycosylation Glycosylation 1 1 1 10/18/23 20231023 NES 231023 B Cyclic oligosaccharides b such as cyclodextrins are extensively employed as carriers fo drug delivery owing to their remarkable host properties and excellent biocompatibility. Carbohydrates, Conformational Analysis, Cyclic Oligosaccharides, Cycloglycosylation, Glycosylation. [Extracted from the article]