glycosyl fluorides using sulfur(VI) hexafluoride as an inexpensive and safe fluorinating agent and 4,4′-dimethoxybenzophenone as a readily available organic photocatalyst. This mild method was employed to generate 16 different glycosyl fluorides, including the substrates with acid and base labile functionalities, in yields of 43%–97%, and it was applied in continuous flow to accomplish fluorination on an
Electrochemical Synthesis of Glycosyl Fluorides Using Sulfur(VI) Hexafluoride as the Fluorinating Agent
作者:Sungjin Kim、Pavel Nagorny
DOI:10.1021/acs.orglett.2c00431
日期:2022.4.1
different glycosyl fluorides in 73–98% yields on up to a 5 g scale that relies on the use of SF6 as an inexpensive and safe fluorinating agent. Cyclic voltammetry and related mechanistic studies carried out subsequently suggest that the active fluorinating species generated through the cathodic reduction of SF6 are transient under these reductive conditions and that the sulfur and fluoride byproducts are
该手稿描述了 17 种不同糖基氟化物的电化学合成,产量高达 5 g,产量为 73–98%,依赖于使用 SF 6作为廉价且安全的氟化剂。随后进行的循环伏安法和相关机理研究表明,通过 SF 6阴极还原产生的活性氟化物质在这些还原条件下是瞬态的,并且硫和氟化物副产物被 Zn(II) 有效清除以生成良性盐。
α and βl-Fucopyranosyl oxyamines: key intermediates for the preparation of fucose-containing glycoconjugates by oxime ligation
unexpected alpha and beta anomer ratio was obtained in spite of the presence of an acetate participating group at the carbon 2, particularly the 1,2-cis glycosylation was largely favoured in acetonitrile. The resulting alpha and beta N-oxyphthalimido fucopyranosyl derivatives were finally deprotected with methylhydrazine to obtain the corresponding free aminooxylated fucopyranosyls. The structure of single-crystal
dictated primarily by the preference of the bulky aromatic aglycon to orient equatorially, due to the strong repulsion of the aglycon. The anomerization is directed secondarily by the presence of 1,3-diaxialinteractions in the sugar moiety.
Trisaccharides embodying the Fuc-alpha-(1-2)-Gal or the Fuc-alpha-(1-2)-Glc substructure can be built up under neutral conditions by glycosylation of selectively deprotected glycosyl acceptor disaccharides with 2,3,4-tri-O-benzyl fucosyl fluoride in 0.07 M solutions of LiClO4 in CH2Cl2. The glycosyl and the galactosyl trisaccharides, which are stereoisomers of the carbohydrate determinant of the human blood group H, are obtained in high yield and with complete alpha-selectivity. The glycosyl acceptor disaccharides with a deblocked 2-OH group in the saccharide unit are obtained by treatment of the respective 1,2-anhydro carbohydrates with glycosyl acceptors in 0.07 M LiClO4/CH2Cl2.