A novel synthesis of 2-deoxy-alpha-glycosides. 1977

K Tatsuta, and K Fujimoto, and M Kinoshita

The key step of the synthesis involves the reaction of glycals [3,4,6-tri-O-acetyl-D-glucal (1), the new glycal derivative 4-O-acetyl-1,5-anhydro-2,6-dideoxy-3-C-methyl-3-O-methyl-L-ribo-hex-1-enitol (2), and 3-acetamido-4,6-di-O-acetyl-1,5-anhydro-2,3-dideoxy-D-arabino-hex-1-enitol (3)] with 1.5 molar equivalents of several alcohols in the presence of N-bromosuccinimide in acetonitrile to give mainly the corresponding 2-bromo-2-deoxy-alpha-glycopyranosides (4--21). The glycopyranosides (4-8 and 16-21) from 1 and 3 have the alpha-D-manno configuration and those (10--15) from 2 have the alpha-L-altro configuration. The yields are high from 1, virtually quantitative from 2, and moderate from 3. Debromination of the 2-bromo-2-deoxy compounds with tributylstannane and a radical initiator gives the corresponding 2-deoxy-alpha-glycopyranosides (22-38) in quantitative yields. In particular, the branched-chain glycal 2 reacts with alcohols to give exclusively the corresponding alpha-glycopyranosides (27--32) of cladinose in strikingly high overall yields. The stereoselectivity and regiospecificity of the bromination reaction are described. 1,3-Dibromo-5,5-dimethylhydantoin and N-bromoacetamide are also found to be useful for the reaction.

UI MeSH Term Description Entries
D008722 Methods A series of steps taken in order to conduct research. Techniques,Methodological Studies,Methodological Study,Procedures,Studies, Methodological,Study, Methodological,Method,Procedure,Technique
D003837 Deoxy Sugars Sugars that in which one or more hydroxyl groups of the pyranose or furanose ring is substituted by hydrogen. Deoxy Sugar,Sugar, Deoxy,Sugars, Deoxy
D006027 Glycosides Any compound that contains a constituent sugar, in which the hydroxyl group attached to the first carbon is substituted by an alcoholic, phenolic, or other group. They are named specifically for the sugar contained, such as glucoside (glucose), pentoside (pentose), fructoside (fructose), etc. Upon hydrolysis, a sugar and nonsugar component (aglycone) are formed. (From Dorland, 28th ed; From Miall's Dictionary of Chemistry, 5th ed) Glycoside

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