Synthesis and structure determination of some nonanomerically C–C-linked serine glycoconjugates structurally related to mannojirimycin Original Research Article

The Bucherer–Bergs reaction of methyl 2,3-O-isopropylidene-α-d-lyxo-hexofuranosid-5-ulose gave (4′S)-4′-carbamoyl-4′-[methyl (4R)-2,3-O-isopropylidene-β-l-erythrofuranosid-4-C-yl]-oxazolidin-2′-one instead of expected hydantoins. A mixture of hydantoins––(5′R)-triphenylmethoxymethyl-5′-[methyl (4R)-2,3-O-isopropylidene-β-l-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione and (5′S)-triphenylmethoxymethyl-5′-[methyl (4R)-2,3-O-isopropylidene-β-l-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione was obtained from the 5-ulose having protected primary OH group at C-6. The 4′-S configuration of 2 as well as 5′-S configuration of (5′S)-hydroxymethyl-5′-[methyl (4R)-2,3-O-isopropylidene-β-l-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione (9) was confirmed by X-ray crystallography. Corresponding α-amino acid––methyl (5S)-5-amino-5-C-carboxy-5-deoxy-α-d-lyxo-hexofuranoside (alternative name: 2-[methyl (4R)-β-l-erythrofuranosid-4-C-yl]-l-serine) (11) was obtained from the hydantoin 9 by acid hydrolysis of the isopropylidene and trityl groups followed by basic hydrolysis of the hydantoin ring. Analogous derivatives with 5-R configuration, formed in a minority, were also isolated and characterised.