| 1. |
- Langer, Vratislav, 1949, et al.
(författare)
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2-(1H-Benzimidazol-2-ylsulfanyl)butanoic acid
- 2006
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Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E62:6, s. o2138-o2140
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Tidskriftsartikel (refereegranskat)abstract
- The title compound, C11H12N2O2S, forms ionic crystals consisting of protonated benzimidazole cations and carboxylic acid anions, C11H13N2O2+·C11H11N2O2-. In both ions, the bicyclic 1H-benzimidazole core is essentially planar. The plane of the 2-alkylsulfanyl substituent is almost coplanar with the benzimidazole plane. The three-dimensional packing is stabilized by strong intermolecular N-H...O and O-H...N interactions and weak C-H...O intermolecular hydrogen bonds.
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| 2. |
- Langer, Vratislav, 1949, et al.
(författare)
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3-O-Benzoyl-1,2-O-isopropylidene-β-D-fructopyranose
- 2005
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Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E61:7, s. o2172-o2174
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Tidskriftsartikel (refereegranskat)abstract
- In the structure of the title compound, C16H20O7, the five-membered 1,3-dioxolane ring is disordered with two different positions, A and B (1/1); it adopts the OT4 conformation slightly distorted towards E4 for molecule A, and the 1E conformation distorted towards 1TO for molecule B. The pyranose ring adopts an almost ideal 1C4 conformation. The three-dimensional packing is stabilized by strong intermolecular O-H...O interactions and weak C-H...O hydrogen bonds.
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| 3. |
- Langer, Vratislav, 1949, et al.
(författare)
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6-O-Cyanomethyl-1,2:3,4-di-O-isopropylidene-α-D-galactopyranose
- 2005
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Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E61:3, s. o779-o781
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of the title compound, C14H21NO6, revealed a highly distorted conformation of the six-membered pyranose ring. The presence of two five-membered 1,3-dioxolane rings fused to the pyranose ring at the 1,2- and 3,4-positions is responsible for the severe deviation from the usual chair conformation of the pyranose ring. The three-dimensional packing is stabilized by weak hydrogen bonds of the C-H...O type.
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| 4. |
- 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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| 5. |
- Micova, Julia, et al.
(författare)
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Synthesis and structure determination of some glycoconjugates related to mannojirimycin and serine
- 2005
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Ingår i: ChemZi. - 1336-7242. ; 1:1, s. 222-223
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Glycoconjugates of lipids and proteins represent a very important group of organic compounds. Due to their responsibility for recognition in biological events, there is growing interest in the use of synthetic glycopeptides as model compounds.(5S)-5-Triphenylmethoxymethyl-[5-methyl (4R)-2,3-O-isopropylidene-β-L-erythrofuranosid-4-C-yl]-imidazolidin-2,4-dione(1) was synthesized from methyl 6-O-trityl-2,3-O-isopropylidene-α-D-lyxo-hexofuranosid-5-ulose and applying the Bucherer-Bergs reaction. As a minor product, the isomer 3 with 5-R configuration was isolated. Corresponding α-amino acids 5 and 6 were obtained from the above hydantoins by the selective acid hydrolysis of the trityl and isopropylidene groups followed by basic hydrolysis of the hydantoin ring. 2-Oxazolidinone derivate 7 instead of the expected hydantoin was obtained starting from 6-O-unprotected 5-ulose. The configuration at C-5' atom was unambiguosly established by single-crystal X-ray diffraction analysis of the hydantoin derivative 2.
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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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