Preparation of 2,3-alloepimino-2,3-dideoxy-β-cyclodextrin as a versatile scaffold candidate for the hetero-2,3-bifunctionalization

3^A-Azido-3^A-deoxy-altro-β-cyclodextrin, although having as many as 20 different hydroxyl groups, was selectively sulfonylated at the 2^A-OH of the altrose residue by 2-mesitylenesulfonyl chloride to give 3^A-azido-3^A-deoxy-2^A-O-mesitylenesulfonyl-altro-β-cyclodextrin. A one-pot reduction-intramolecular substitution of the latter afforded the title compound as a promising intermediate for the introduction of two different functional groups to two different positions of one sugar unit, which has not been succeeded hitherto.     

Highly Selective Preparation of 3-and 6-Modified Mannose/Altrose Derivatives

Introduction Asacoretrisaccharide,the3,6branchedtriman nosaccharideunit(Manα16Man31αMan)iswidely expressedonalotofglycoproteins.Itexistsinallas paragines linkedoligosaccharides(N glycans)andthe majorConAbindingepitopeonoligosaccharide type carbohydrate[…     

Synthesis of the C‐Glycoside of Methyl α‐d‐Altropyranosyl‐(1→4)‐α‐d‐glucopyranoside

The C‐glycoside of methyl α‐d‐altropyranosyl‐(1→4)‐α‐d‐glucopyranoside 2 was prepared in a convergent fashion, from readily available precursors, 4‐O‐tert‐butyldiphenylsilyl‐1,2‐O‐isopropylidene‐d‐erythro‐S‐phenyl monothiohemiacetal 13 (five steps from D‐ribose) and the known acid, methyl 2,3,6‐tri‐O‐benzyl‐4‐C‐(carboxymethyl)‐4‐deoxy‐α‐d‐glucopyranoside 17 (seven steps from methyl α‐d‐glucopyranoside). The key reactions in the synthesis are the oxocarbenium ion cyclization of thioacetal‐enol ether 19 to a C1 substituted glycal 20, and the stereoselective hydroboration of 20 to the α‐C‐altroside 21.     

Hetero-bifunctionalization of the secondary face of β-cyclodextrin: selective 3-sulfonylation and subsequent 2,3-epoxidation of 3-azido-3-deoxy-altro-β-cyclodextrin

3^A-Azido-3^A-deoxy-altro-β-cyclodextrin, which has 20 different hydroxyl groups, was selectively sulfonylated by 1-naphthalenesulfonyl chloride at the 3^G-OH of the glucoside residue as well as the 2^A-OH of the altroside one. Alkali treatment of the 3^G-sulfonate gave successfully the 2^G,3^G-epoxyalloside with the 3^A-azido group being left unaffected. Both the 3^G-sulfonate and 2^G,3^G -alloepoxide species of 3^A-azido-3^A-deoxy-altro-β-cyclodextrin not only have two sugar units being modified differently, but also can serve as versatile starting materials for the syntheses of bifunctional cyclodextrins with diverse combination of different functionalities.     

Selective mono-O-sulfonylation of A,B-di-altro- β-cyclodextrin by utilizing restricted orientation of a guest-type sulfonylating reactant in the elliptically distorted cavity: the 2-O- and 3-O-2-naphthalenesulfonates as a versatile scaffold to prepare artificial enzymes with controlling substrate orientation

A,B-di-altro-β-cyclodextrin, which has 21 different hydroxyl groups, was selectively sulfonylated by 2-naphthalenesulfonyl chloride at the 2^A-OH of the altrose residue and the 3^G-OH of the glucoside residue adjacent to the altroside residue. The latter sulfonate provides for the first time a possibility for the synthesis of functional cyclodextrins that have two altrose residues adjacent to the functionalized one (either of glucose type or of altrose type) to control the orientation of substrate.