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

Abstract

The Bucherer–Bergs reaction of methyl 2,3- O-isopropylidene-α- d- lyxo-hexofuranosid-5-ulose gave (4′ S)-4′-carbamoyl-4′-[methyl (4 R)-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 (4 R)-2,3- O-isopropylidene-β- l-erythrofuranosid-4- C-yl]-imidazolidin-2′,4′-dione and (5′ S)-triphenylmethoxymethyl-5′-[methyl (4 R)-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 (4 R)-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 (5 S)-5-amino-5- C-carboxy-5-deoxy-α- d- lyxo-hexofuranoside (alternative name: 2-[methyl (4 R)-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.