Glycal

About: Glycal is a research topic. Over the lifetime, 897 publications have been published within this topic receiving 17422 citations.

Stereoselective Synthesis of the β-Anomer of 4′-Thionucleosides Based on Electrophilic Glycosidation to 4-Thiofuranoid Glycals.

Abstract: Three types of 4-thiofuranoid glycal with different 3,5-O-silyl protecting groups were prepared and their electrophilic glycosidation was investigated. The 3,5-bis-O-(tert-butyldimethylsilyl)-4-thiofuranoid glycal (5) was obtained through mesylation of 2-deoxy-4-thio-D-erythro-pentofuranose (4) and subsequent base-promoted elimination, while thermal elimination of sulfoxide derivatives was suitable for the preparation of 3,5-O-(tetraisopropyldisiloxane-1,3-diyl) (9) and 3,5-O-(di-tert-butylsilylene) (11) 4-thioglycals. The glycosidation reactions of these 4-thioglycals were carried out, in the presence of either PhSeCl or NIS, by using silylated derivatives of uracil, thymine, cytosine, and N(6)-benzoyladenine. Among the three 4-thioglycals, 11 was found to be an excellent glycosyl donor, forming the desired beta-anomer exclusively irrespective of the nucleobase employed.

Chemical synthesis of glycosides and glycomimetics

Abstract: Partial Table of Content CHEMICAL SYNTHESIS OF GLYCOSIDES Trichloroacetimidates (R. Schmidt & K. - H. Jung) Iterative Assembly of Glycals and Glycal Derivatives: The Synthesis of Glycosylated Natural Products and Complex Oligosaccharides (L. Williams, et al.) Thioglycosides (S. Oscarson) Glycosylation Methods: Alkylations of Reducing Sugars (J. Tamura) Other Methods of Glycosylation (L. Panza & L. Lay) Glycolipid Synthesis (H. Ishida) Special Problems in Glycosylation Reactions: 2 - Deoxy Sugars (A. Veyrieres) Orthogonal Strategy in Oligosaccharide Synthesis (O. Kanie) Intramolecular Glycosidation Reactions (J. Madsen & M. Bols) SYNTHESIS OF OLIGOSACCHARIDE MIMICS Saccharide - Peptide Hybrids (H. Wessel) Index.

Synthesis of 2,3‐Unsaturated Glycosides and Disaccharides via Ruthenium(III) Chloride Catalyzed Ferrier Glycosylation.

Abstract: The glycal donor reacts smoothly with several acceptors comprising different functionalities to provide unsaturated glycosides, disaccharides, and amino acid glycoconjugates in good to high yields.

Catalytic Stereoselective Synthesis of β‐Digitoxosides: Direct Synthesis of Digitoxin and C1′‐epi‐Digitoxin.

Abstract: A mild and atom-economic rhenium(V)-catalyzed stereoselective synthesis of β-D-digitoxosides from 6-deoxy-D-allals has been described. This β-selective glycosylation was achieved probably because of the formation of corresponding α-digitoxosides disfavored by 1,3-diaxial interaction. In addition, this method has been successfully applied to the synthesis of digitoxin trisaccharide glycal for the direct synthesis of digitoxin and C1'-epi-digitoxin.

New anthracyclin derivative

Abstract: NEW MATERIAL:An anthracyclin derivative of formulaI(R 1 is H, hydroxyl, lower alkanoyloxy; R is H, residue of aminosaccharide of formula II) or its acid adduct. EXAMPLE: 4-Demethoxy-11-deoxydaunomycin. USE: Antibiotic against gram-positive bacteria, antitumor agent against solid tumor and ascitic tumor. It is given parenterally. PREPARATION: For example, the reaction between 5-methoxytetralone of formula IV and a Grignard reagent is followed by hydrolysis and the reaction product is made to react with phthalic anhydride to give 4-demethoxy-7,11-dideoxydaunomycin of formula V. Then, selective halogenation at the 14-position is effected using N- bromosuccinimide and the product is acylated and hydrolyzed to form a compound of formula VI. Further, the compound is made to react with a glycal to form a glycoside, then the protecting groups are removed to give the compound of formula VII. COPYRIGHT: (C)1982,JPO&Japio