Preparation of C-Glycoside Pendant β^2- and β^<2,2>-Amino Acids
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Facile preparations of <I>C</I>-glycosyl β<SUP>2</SUP>- and β<SUP>2,2</SUP>-amino acids are described. Selective formation of a β-<I>C</I>-glycoside linkage was achieved by the reaction of a 2,3,4,6-tetra-<I>O</I>-acetyl-α-<small>D</small>-gluco/galactopyranosyl bromide (α-acetobromoglucose/galactose) with the carbanion of a cyanoacetate ester. Crystallization selectively afforded one of two diastereomers with respect to the chiral center at the α-carbon of the side chain (C-2), however, this compound was found to epimerize during the following nitrile reduction. Separation of the diastereomers was achieved via the Fmoc derivatives. Diastereomerically pure <I>C</I>-glycosyl β<SUP>2,2</SUP>-amino acids were prepared by diastereoselective alkylation of <I>C</I>-glycosylated enolate, followed by nitrile hydrogenation. The present procedure serves as an efficient route to <I>C</I>-glycosylated β-amino acids containing a non-biodegradable linkage.
- Bull. Chem. Soc. Jpn.
Bull. Chem. Soc. Jpn. 81(5), 606-616, 2008-05-15
The Chemical Society of Japan