Synthesis and structure determination of some sugar amino acids related to alanine and 6-deoxymannojirimycin Original Research Article

(5′R)-5′-Methyl-5′-[methyl (4S)-2,3-O-isopropylidene-β-l-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione was synthesised starting from methyl 6-deoxy-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-α-d-lyxo-hexofuranoside (alternative name: 2-[methyl (4S)-2,3-O-isopropylidene-β-l-erythrofuranosid-4-C-yl]-d-alanine) was obtained from the above hydantoin by acid hydrolysis of the isopropylidene group followed by basic hydrolysis of the hydantoin ring. Total deprotection afforded 5-C-carboxy-6-deoxymannojirimycin. Analogously, methyl (5S)-5-amino-5-C-carboxy-5,6-dideoxy-α-l-lyxo-hexofuranoside and 5-C-carboxy-6-deoxy-l-mannojirimycin were prepared from the corresponding (5′S)-5′-methyl-5′-[methyl (4R)-2,3-O-isopropylidene-β-d-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione starting from methyl 6-deoxy-2,3-O-isopropylidene-α-l-lyxo-hexofuranosid-5-ulose.