| 1. |
- Bella, M., et al.
(författare)
-
Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement
- 2014
-
Ingår i: Beilstein Journal of Organic Chemistry. - : Beilstein Institut. - 1860-5397. ; 10, s. 1942-1950
-
Tidskriftsartikel (refereegranskat)abstract
- The Grignard reaction of 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside and benzylmagnesium chloride (or bromide) afforded a non-separable mixture of diastereomeric benzyl carbinols and diastereomeric o-tolyl carbinols. The latter resulted from an unexpected benzyl to o-tolyl rearrangement. The proportion of benzyl versus o-tolyl derivatives depended on the reaction conditions. Benzylmagnesium chloride afforded predominantly o-tolyl carbinols while the application of benzylmagnesium bromide led preferably to the o-tolyl carbinols only when used in excess or at higher temperatures. The structures of the benzyl and o-tolyl derivatives were confirmed unambiguously by NMR spectral data and X-ray crystallographic analysis of their 5-ketone analogues obtained by oxidation of the corresponding mixture of diastereomeric carbinols. A possible mechanism for the Grignard reaction leading to the benzyl -> o-tolyl rearrangement is also proposed.
|
|
| 2. |
- Hirsch, Jan, et al.
(författare)
-
Synthesis and Molecular Structure of Methyl 4-O-methyl-α-D-glucopyranuronate
- 2005
-
Ingår i: Molecules. - 1420-3049 .- 1420-3049. ; 10:1, s. 251-258
-
Tidskriftsartikel (refereegranskat)abstract
- A method for the preparation of methyl 4-O-methyl-α-D-glucopyranuronate and its single crystal X-ray structure determination are reported. The molecule adopts an almost ideal 4C1 (OC3) conformation.
|
|
| 3. |
- Langer, Vratislav, 1949, et al.
(författare)
-
2-(1H-Benzimidazol-2-ylsulfanyl)butanoic acid
- 2006
-
Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E62:6, s. o2138-o2140
-
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.
|
|
| 4. |
- Langer, Vratislav, 1949, et al.
(författare)
-
2,3:4,6-Di-O-isopropylidene-α-L-sorbofuranose and 2,3-O-isopropylidene-α-L-sorbofuranose
- 2009
-
Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C65:4, s. o151-o154
-
Tidskriftsartikel (refereegranskat)abstract
- In the title compounds, C12H20O6, (I), and C9H16O6, (II), the five-membered furanose ring adopts a 4T3 conformation and the five-membered 1,3-dioxolane ring adopts an E3 conformation. The six-membered 1,3-dioxane ring in (I) adopts an almost ideal OC3 conformation. The hydrogen-bonding patterns for these compounds differ substantially: (I) features just one intramolecular O-H...O hydrogen bond [O...O = 2.933 (3)Å], whereas (II) exhibits, apart from the corresponding intramolecular O-H...O hydrogen bond [O...O = 2.7638 (13)Å], two intermolecular bonds of this type [O...O = 2.7708(13) and 2.7730(12) Å]. This study illustrates both the similarity between the conformations of furanose, 1,3-dioxolane and 1,3-dioxane rings in analogous isopropylidene-substituted carbohydrate structures and the only negligible influence of the presence of a 1,3-dioxane ring on the conformations of furanose and 1,3-dioxolane rings. In addition, in comparison with reported analogs, replacement of the -CH2OH group at the C1-furanose position by another group can considerably affect the conformation of the 1,3-dioxolane ring.
|
|
| 5. |
- Langer, Vratislav, 1949, et al.
(författare)
-
2-(4-Hydroxyphenyl)-4,4-dimethyl-2-oxazoline: X-ray and density functional theory study
- 2006
-
Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C62:7, s. o416-o418
-
Tidskriftsartikel (refereegranskat)abstract
- In the crystal structure of the title compound, C11H13NO2, there are strong intermolecular O-H...N hydrogen bonds which, together with weak intramolecular C-H...O hydrogen bonds, lead to the formation of infinite chains of molecules, held together by weak intermolecular C-H...O hydrogen bonds. A theoretical investigation of the hydrogen bonding, based on density functional theory (DFT) employing periodic boundary conditions, is in agreement with the experimental data. The cluster approach shows that the influence of the crystal field and of hydrogen-bond formation are responsible for the deformation of the 2-oxazoline ring, which is not planar and adopts a 4T3 (C3TC2) conformation.
|
|
| 6. |
- Langer, Vratislav, 1949, et al.
(författare)
-
3-(4-Bromophenyl)-5-(4-dimethylaminophenyl)-1-phenyl-2-pyrazoline: X-ray and density functional theory (DFT) studies
- 2007
-
Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C63:6, s. o340-o342
-
Tidskriftsartikel (refereegranskat)abstract
- In the crystal structure of the title compound, C23H22BrN3, a strong conjugation of the pyrazoline chromophore with the aromatic rings at positions 1 and 3 is observed, as well as a significant shift in the synclinal→synperiplanar direction. The absolute structure was unequivocally determined. In the absence of clasical hydrogen-bond donors, the structure is stabilized by weak C-H…π interactions. This paper also reports the electronic structure of the title compound using NBO (natural bond order) analysis. The contributions of lone pairs to the relevant bonds were revealed.
|
|
| 7. |
- Langer, Vratislav, 1949, et al.
(författare)
-
3-O-Benzoyl-1,2-O-isopropylidene-β-D-fructopyranose
- 2005
-
Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E61:7, s. o2172-o2174
-
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.
|
|
| 8. |
- Langer, Vratislav, 1949, et al.
(författare)
-
6-O-Cyanomethyl-1,2:3,4-di-O-isopropylidene-α-D-galactopyranose
- 2005
-
Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E61:3, s. o779-o781
-
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.
|
|
| 9. |
- Langer, Vratislav, 1949, et al.
(författare)
-
Crystal structures of three isomeric forms of hydoxyphenyl-2-oxazoline
- 2005
-
Ingår i: Proceedings of XLVIII. Congress of Polish Chemical Society, Poznan 18-22 september 2005. - 8389936070 ; 1, s. S7-P2
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The crystal structures of three positionally isomeric compounds, 2-(2-hydroxyphenyl)-2-oxazoline, C9H9NO2, (I), 2-(3-hydroxyphenyl)-2-oxazoline, C9H9NO2, (II), and 2-(4-hydroxyphenyl)-2-oxazoline, C9H9NO2, (III), [alternative names of the title compounds are: 2-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (I), 3-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (II), and 4-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (III)] have been determined. The title compounds were prepared in the course of our research focused at cyclic imino ethers and their utilization in polymer chemistry because hydroxyphenyl-2-oxazolines are known to produce poly(ether-amides) on heating of the monomer. In these compounds, the deviation from coplanarity of oxazoline and benzene rings is dependent on the position of the hydroxyl group at phenyl moiety. The coplanar arrangement in (I) is stabilized by a strong intramolecular O-H...N hydrogen bond. In (II) the hydroxyl group is hydrogen bonded to the ring nitrogen atom on adjacent molecule.Surprisingly, the 2-oxazoline ring of one molecule in asymmetric unit of (II) adopts 3T4 (C2TC3) conformation, while 2-oxazoline ring in the other molecule, as well as that in (I) and (III), is nearly planar, as expected. Tetramers of molecules of (II) are formed and they are bound together via weak C-H...N hydrogen bonds. In (III), strong intermolecular O-H...N hydrogen bonds and weak intramolecular C-H...O hydrogen bonds lead to the formation of an infinite chain of molecules perpendicular to the b direction. The theoretical investigation of H-bonds, based on density functional theory (DFT) employing periodic boundary conditions, has been done using Vienna Ab initio Simulation Package (VASP).
|
|
| 10. |
- Langer, Vratislav, 1949, et al.
(författare)
-
Preparation and Crystal Structure of (1S, 5S, 7S, 8R)-8-Hydroxy-7-phenyl-2,6-dioxabicyclo[3.3.0]octan-3-one
- 2003
-
Ingår i: Molecules. - 1420-3049 .- 1420-3049. ; 8:7, s. 599-606
-
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.
|
|
| 11. |
- Langer, Vratislav, 1949, et al.
(författare)
-
Three isomeric forms of hydroxyphenyl-2-oxazoline: 2-(2-hydroxyphenyl)-2-oxazoline, 2-(3-hydroxyphenyl)-2-oxazoline and 2-(4-hydroxyphenyl)-2-oxazoline
- 2005
-
Ingår i: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C61:10, s. o602-o606
-
Tidskriftsartikel (refereegranskat)abstract
- Crystal structures are reported for three isomeric compounds, namely 2-(2-hydroxyphenyl)-2-oxazoline, (I), 2-(3-hydroxyphenyl)-2-oxazoline, (II), and 2-(4-hydroxyphenyl)-2-oxazoline, (III), all C9H9NO2 [systematic names: 2-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (I), 3-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (II), and 4-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (III)]. In these compounds, the deviation from coplanarity of the oxazoline and benzene rings is dependent on the position of the hydroxy group on the benzene ring. The coplanar arrangement in (I) is stabilized by a strong intramolecular O-H...N hydrogen bond. Surprisingly, the 2-oxazoline ring in molecule B of (II) adopts a 3T4 (C2TC3) conformation, while the 2-oxazoline ring in molecule A, as well as that in (I) and (III), is nearly planar, as expected. Tetramers of molecules of (II) are formed and they are bound together via weak C-H...N hydrogen bonds. In (III), strong intermolecular O-H...N hydrogen bonds and weak intramolecular C-H...O hydrogen bonds lead to the formation of an infinite chain of molecules perpendicular to the b direction. This paper also reports a theoretical investigation of hydrogen bonds, based on density functional theory (DFT) employing periodic boundary conditions.
|
|
| 12. |
- Micova, Julia, et al.
(författare)
-
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
-
Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 338:19, s. 1917-1924
-
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.
|
|
| 13. |
- Micova, Julia, et al.
(författare)
-
Synthesis and structure determination of some glycoconjugates related to mannojirimycin and serine
- 2005
-
Ingår i: ChemZi. - 1336-7242. ; 1:1, s. 222-223
-
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.
|
|
| 14. |
- Micova, Julia, et al.
(författare)
-
Synthesis and structure determination of some nonanomerically C—C-linked serine glycoconjugates structurally related to mannojirimycin
- 2004
-
Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 339:13, s. 2187-2195
-
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.
|
|
| 15. |
- Micova, Júlia, et al.
(författare)
-
Synthesis, Crystal Structure, and Conformation of Methyl 5-O-acetyl-5-cyano-6-deoxy-2,3-O-isopropylidene-β-L-gulofuranoside
- 2002
-
Ingår i: Molecules. - 1420-3049 .- 1420-3049. ; 7:5, s. 437-446
-
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.
|
|
| 16. |
- Micova, Julia, et al.
(författare)
-
Synthesis of 4-Carbamoyl-2-oxazolidinones C-4-Linked with a Saccharide Moiety via Bucherer-Bergs Reaction of Hexofuranos-5-uloses
- 2002
-
Ingår i: Synlett. - : Georg Thieme Verlag KG. - 1437-2096 .- 0936-5214. ; 2002:10, s. 1715-1717
-
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.
|
|
| 17. |
- Scholtzová, Eva, et al.
(författare)
-
Crystal Structure, Infrared Spectra and DFT Study of Benzyl 2,3-Anhydro-β-D-Ribopyranoside
- 2011
-
Ingår i: Journal of Chemical Crystallography. - 1074-1542 .- 1572-8854. ; 41:2, s. 167-174
-
Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of benzyl 2,3-anhydro-β-D-ribopyranoside is orthorhombic, P212121, Z = 4. The pyranose ring adopts the EO conformation distorted considerably to the 5HO direction. The molecules of the title compound are linked into infinite chains running along the a-axis by bifurcated O–H···O hydrogen bonds. Interaction energies of these hydrogen bonds are significantly different, ~−5.4 for the bond with the smaller and ~−1.1 kcal/mol for the bond with the larger O···O separation. The hydrogen-bond pattern is completed by the two weaker C–H···O intermolecular hydrogen bonds, aiming at the epoxy oxygen atom. IR vibrational spectrum was interpreted by means of comparison with the full list of vibrational modes predicted using DFT method in the solid state. While till 1495 cm−1 the individual bands can be reconciled with single calculated modes, the region below this limit is populated by heavily overlapped HCH, HCO, HOC, COC and HCC bending modes merged with few ν(CC) and ν(CO) modes. The respective “red” shifts of the positions of the ν(OH) bands correlate well with the size of the O···O separation.
|
|
| 18. |
- Smrcok, Lubomir, et al.
(författare)
-
On hydrogen bonding in 1,6-anhydro-β-D-glucopyranose (levoglucosan): X-ray and neutron diffraction and DFT study
- 2006
-
Ingår i: Acta Crystallographica Section B: Structural Science. - 0108-7681 .- 1600-5740. ; B62:5, s. 912-918
-
Tidskriftsartikel (refereegranskat)abstract
- The geometry of hydrogen bonds in 1,6-anhydro-β-D-glucopyranose (levoglucosan) is accurately determined by refinement of time-of-flight neutron single-crystal diffraction data. Molecules of levoglucosan are held together by a hydrogen-bond array formed by a combination of strong O-H...O and supporting weaker C-H...O bonds. These are fully and accurately detailed by the neutron diffraction study. The strong hydrogen bonds link molecules in finite chains, with hydroxyl O atoms acting as both donors and acceptors of hydroxyl H atoms. A comparison of molecular and solid-state DFT calculations predicts red shifts of O-H and associated blue shifts of C-H stretching frequencies due to the formation of hydrogen bonds in this system.
|
|
| 19. |
- Steiner, Bohumil, et al.
(författare)
-
Cyanohydrins from methyl 6-deoxy-2,3-O-isopropylidene-alpha-L-lyxo-hexofuranosid-4-ulose via Bucherer-Bergs and Strecker reactions
- 2013
-
Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 369, s. 31-37
-
Tidskriftsartikel (refereegranskat)abstract
- The formation of methyl 4-cyano-6-deoxy-2,3-O-isopropylidene-alpha-L-talopyranoside (3), methyl 4-cyano-6-deoxy-2,3-O-isopropylidene-alpha-L-mannopyranoside (4), methyl 4-cyano-6-deoxy-2,3-O-isopropylidene-beta-D-allopyranoside (5), and methyl 4-cyano-6-deoxy-2,3-O-isopropylidene-beta-D-gulopyranoside (7) from methyl 6-deoxy-2,3-O-isopropylidene-alpha-L-lyxo-hexopyranosid-4-ulose (1) under Strecker amino nitrile synthesis and Bucherer-Bergs hydantoin synthesis reaction conditions, respectively, is reported. Their structures were determined on the basis of NMR and mass spectral data. The configurations of free cyanohydrins 3 and 4 and 4-O-acetylated cyanohydrins 6 and 8 (obtained by acetylation of 5 and 7, respectively) were established by single-crystal X-ray analysis. The conformations of the six-membered pyranose ring and five-membered 1,3-dioxolane ring in compounds 3, 4, 6, and 8 are also reported.
|
|
| 20. |
- Steiner, Bohumil, et al.
(författare)
-
Some non-anomerically C-C-linked carbohydrate amino acids related to leucine - synthesis and structure determination
- 2003
-
Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 338:13, s. 1349-1357
-
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.
|
|
| 21. |
- Steiner, Bohumil, et al.
(författare)
-
Synthesis and X-ray structure of a C5–C4-linked glucofuranose–oxazolidin-2-one
- 2009
-
Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 344:15, s. 2079-2082
-
Tidskriftsartikel (refereegranskat)abstract
- The formation of (4R)-4-carbamoyl-4-[(4R)-3-O-benzyl-1,2-O-isopropylidene-β-L-threofuranos-4-C-yl]-oxazolidin-2-one instead of expected imidazolidin-2,4-dione (hydantoin) derivative from 5-amino-5-cyano-5-deoxy-3-O-benzyl-1,2-O-isopropylidene-α-D-glucofuranose or 3-O-benzyl-1,2-O-isopropylidene-α-D-xylo-hexofuranos-5-ulose under Bucherer–Bergs reaction conditions is reported. Single crystal X-ray diffraction data revealed that 3T4 is the prefered conformation for the furanose ring, while E2 and 2T1 conformations are adopted by the 1,3-dioxolane and 2-oxazolidinone five-membered rings, respectively.
|
|
