Some non-anomerically CC-linked carbohydrate amino acids related to leucine—synthesis and structure determination Original Research Article

(5′R)-5′-Isobutyl-5′-[methyl (4R)-2,3-O-isopropylidene-β-l-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione was synthesised starting from methyl 2,3-O-isopropylidene-α-d-lyxo-pentodialdo-1,4-furanoside via methyl 6-deoxy-6-isopropyl-2,3-O-isopropylidene-α-d-lyxo-hexofuranosid-5-ulose applying the Bucherer–Bergs reaction. Its 5′-R configuration was confirmed by X-ray crystallography. Corresponding α-amino acid–methyl (5R)-5-amino-5-C-carboxy-5,6-dideoxy-6-isopropyl-α-d-lyxo-hexofuranoside (alternative name: 2-[methyl (4R)-β-l-erythrofuranosid-4-C-yl]-d-leucine) was obtained from the above hydantoin by acid hydrolysis of the isopropylidene group followed by basic hydrolysis of the hydantoin ring. Analogous derivatives with 5S configuration, formed in a minority, were also isolated and characterised.