| 1. |
- Langer, Vratislav, 1949, et al.
(författare)
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Preparation and Crystal Structure of (1S, 5S, 7S, 8R)-8-Hydroxy-7-phenyl-2,6-dioxabicyclo[3.3.0]octan-3-one
- 2003
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Ingår i: Molecules. - 1420-3049 .- 1420-3049. ; 8:7, s. 599-606
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Tidskriftsartikel (refereegranskat)abstract
- The absolute configuration at two newly formed stereogenic centres (5S, 7S) during the key steps of the total synthesis of naturally occuring goniothalesdiol was established by single-crystal X-ray diffraction analysis relative to stereocentres (1S, 8R) of the title compound (alternatively named 3,6-anhydro-2-deoxy-6-phenyl-L-ido-1,4-hexonolactone, C12H12O4). The conformation of both 5-membered lactone and furanose fused rings is also discussed.
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| 2. |
- Micova, Julia, et al.
(författare)
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Characterisation and X-ray crystallography of products from the Bucherer-Bergs reaction of methyl 2,3-O-isopropylidene-α-D-lyxo-pentodialdo-1,4-furanoside
- 2003
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 338:19, s. 1917-1924
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Tidskriftsartikel (refereegranskat)abstract
- Methyl 2,3-O-isopropylidene-α-D-mannofuranosidurononitrile [alternative name: methyl (5R)-5-C-cyano-2,3-O-isopropylidene-α-D-lyxofuranoside] (2), methyl 2,3-O-isopropylidene-α-D-mannofuranosiduronamide [methyl (5S)-5-C-carbamoyl-2,3-O-isopropylidene-α-D-lyxofuranoside; methyl (5S)-2,3-O-isopropylidene-α-D-lyxo-hexofuranosiduronamide] (3), methyl 2,3-O-isopropylidene-α-D-mannofuranosiduronic acid [methyl (5S)-2,3-O-isopropylidene-α-D-lyxo-hexofuranosiduronic acid] (4), methyl 5-deoxy-2,3-O-isopropylidene-5-ureido-β-L-gulofuranosiduronamide [methyl (5R)-5-deoxy-2,3-O-isopropylidene-5-ureido-α-D-lyxo-hexofuranosiduronamide (5), and (4S,5S,6R)-5,6-dihydro-6-hydroxy-4,5-isopropylidenedioxy-4H-pyrido[2,1-e]imidazolidine-2',4'-dione [IUPAC name: (3aS,4R,8aS)-4-hydroxy-2,2-dimethyl-3a,8a-dihydro-4H-1,3-dioxa-4a,6-diaza-s-indacene-5,7-dione] (6), instead of the expected hydantoin derivative, were obtained from the Bucherer-Bergs reaction of methyl 2,3-O-isopropylidene-α-D-lyxo-pentodialdo-1,4-furanoside (1). The structure of 6 was deduced from NMR and mass spectral data and confirmed by X-ray crystallography. The configuration at C-5 in 2-5 was confirmed by establishing the 5S configuration of 3 by X-ray crystallography. Conformations of the six- and five-membered rings in 3 and 6 are also discussed.
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| 3. |
- Micova, Julia, et al.
(författare)
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Synthesis and structure determination of some nonanomerically C—C-linked serine glycoconjugates structurally related to mannojirimycin
- 2004
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 339:13, s. 2187-2195
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Tidskriftsartikel (refereegranskat)abstract
- The BuchererBergs 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 acidmethyl (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.
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| 4. |
- Micova, Júlia, et al.
(författare)
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Synthesis, Crystal Structure, and Conformation of Methyl 5-O-acetyl-5-cyano-6-deoxy-2,3-O-isopropylidene-β-L-gulofuranoside
- 2002
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Ingår i: Molecules. - 1420-3049 .- 1420-3049. ; 7:5, s. 437-446
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Tidskriftsartikel (refereegranskat)abstract
- Methyl 5-O-acetyl-5-cyano-6-deoxy-2,3-O-isopropylidene-β-L-gulofuranosidewas prepared in high yield from methyl 6-deoxy-2,3-O-isopropylidene-α-D-lyxopentodialdo-1,4-furanoside. The configuration at the C5 atom was unambiguoslyestablished by single crystal X-ray analysis of the corresponding 5-O-acetyl derivative. Theconformation of the furanose and 1,3-dioxolane rings is also discussed.
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| 5. |
- Micova, Julia, et al.
(författare)
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Synthesis of 4-Carbamoyl-2-oxazolidinones C-4-Linked with a Saccharide Moiety via Bucherer-Bergs Reaction of Hexofuranos-5-uloses
- 2002
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Ingår i: Synlett. - : Georg Thieme Verlag KG. - 1437-2096 .- 0936-5214. ; 2002:10, s. 1715-1717
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Tidskriftsartikel (refereegranskat)abstract
- Application of the Bucherer-Bergs reaction to 6-O-unprotected hexofuranos-5-uloses led to the formation of 4-carbamoyl-2-oxazolidinones C-4-linked with a carbohydrate moiety instead of expected carbohydrate-C-5-linked hydantoin (imidazolidin-2,4-dione) derivatives. Starting from hexofuranos-5-uloses having all hydroxyl groups suitably protected, only corresponding saccharide-linked hydandoins were obtained.
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| 6. |
- Steiner, Bohumil, et al.
(författare)
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Some non-anomerically C-C-linked carbohydrate amino acids related to leucine - synthesis and structure determination
- 2003
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 338:13, s. 1349-1357
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Tidskriftsartikel (refereegranskat)abstract
- (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.
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