Synthetic Glycomacromolecules of Defined Valency, Absolute Configuration, and Topology Distinguish between Human Lectins
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ABSTRACT:
SUBMITTER: Hartweg M
PROVIDER: S-EPMC8549053 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Reactions of O-peracylated C-(1-bromo-β-d-glucopyranosyl)formamides with thioamides furnished the corresponding glucopyranosylidene-spiro-thiazolin-4-one. While O-debenzoylations under a variety of conditions resulted in decomposition, during O-deacetylations the addition of MeOH to the thiazolinone moiety was observed, and with EtOH and water similar adducts were isolated or detected. The structure and stereochemistry of the new compounds were established by means of NMR and electronic circular dichroism (ECD) data supported by time-dependent density functional theory ECD (TDDFT-ECD) calculations. TDDFT-ECD calculations could efficiently distinguish the proposed epimeric products having different absolute configuration in the spiro heterocyclic ring.
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Project description:The title compound, known as odorine or roxburghiline {systematic name: (S)-N-[(R)-1-cinnamoylpyrrolidin-2-yl]-2-methyl-butanamide}, C(18)H(24)N(2)O(2), is a nitro-genous compound isolated from the leaves of Aglaia odorata. The absolute configuration was determined by refinement of the Flack parameter with data collected using Cu Kα radiation showing positions 2 and 2' to be S and R, respectively. The pyrrolidine ring adopts an envelope conformation. In the crystal, mol-ecules are linked into chains along [010] by inter-molecular N-H⋯O hydrogen bonds.
| S-EPMC3007931 | biostudies-literature
Project description:The title seco-dammarane triterpenoid, C(27)H(42)O(4) (systematic name: 3-{(3S,3aR,5aR,6S,7S,9aR,9bR)-6,9a,9b-trimethyl-3-[(R)-2-methyl-5-oxotetra-hydro-furan-2-yl]-7-(prop-1-en-2-yl)dodeca-hydro-1H-cyclo-penta-[a]naphthalen-6-yl}propanoic acid), has been isolated for the first time from the seeds of Aglaia forbesii. The mol-ecule has three fused rings and all rings are in trans-fused. The two cyclo-hexane rings are in standard chair conformations and the cyclo-pentane ring adopts an envelope conformation. Its absolute configuration was determined by the refinement of the Flack parameter to 0.26 (17). In the crystal, mol-ecules are linked into chains along [010] by O-H⋯O hydrogen bonds.
| S-EPMC2984085 | biostudies-literature
Project description:The title compound {systematic name: 7-meth-oxy-6-[(1R,2R,5R)-5-methyl-4-oxo-3,6-dioxabicyclo-[3.1.0]hexan-2-yl]-2H-chromen-2-one}, C(15)H(12)O(6), is a coumarin, which was isolated from the roots of Micromelum glanduliferum. There are two mol-ecules in the asymmetric unit with slight differences in bond angles. In both mol-ecules, the furan ring adopts a flattened envelope conformation. In the crystal, mol-ecules are linked by weak C-H?O inter-actions into chains along the a axis. Aromatic ?-? stacking inter-actions with centroid-centroid distances in the range 3.6995?(11)-3.8069?(11)?Å and C?O short contacts [3.030?(2)-3.171?(3)?Å] also occur.
| S-EPMC3151812 | biostudies-other
Project description:A derivative of dolichol was formed and then chemically degraded to a small fragment containing the sole centre of asymmetry of the original molecule. Polarimetric comparison of this derivative with a standard prepared from (R)-citronellol showed dolichol to have an S-configuration at C-3. To determine the optical purity of dolichol a diastereoisomeric derivative was prepared and compared with standard diastereoisomers, which could be resolved by high-pressure liquid chromatography. Dolichols from pig liver, human liver and hen oviduct were analysed by this procedure and were all found to be greater than 95% S-configuration.
| S-EPMC1162022 | biostudies-other
Project description:The title furan-oditerpenoid, known as fibaruretin B (systematic name: 2?,3?-dihy-droxy-2,3,7,8?-tetra-hydro-penianthic acid lactone), C(20)H(24)O(7), was isolated from the roots of Arcangelisia flava. The absolute configurations at positions 2, 3, 4, 4a, 7, 9, 10a and 10b of fibaruretin B are S, R, S, R, S, S, S and S, respectively. In the crystal structure, the mol-ecules are linked into infinite chains along the c axis by O-H?O hydrogen bonds and weak C-H?O inter-actions.
| S-EPMC3089215 | biostudies-literature
Project description:The title compound, C(27)H(34)O(5) {systematic name: (4aR,5R,6R,6aS,7R,11aS,11bR)-4a,6-dihy-droxy-4,4,7,11b-tetra-methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca-hydro-phenanthro[3,2-b]furan-5-yl benzoate}, is a cassane furan-oditerpene, which was isolated from the roots of Caesalpinia pulcherrima. The three cyclo-hexane rings are trans fused: two of these are in chair conformations with the third in a twisted half-chair conformation, whereas the furan ring is almost planar (r.m.s. deviation = 0.003?Å). An intra-molecular C-H?O inter-action generates an S(6) ring. The absolute configurations of the stereogenic centres at positions 4a, 5, 6, 6a, 7, 11a and 11b are R, R, R, S, R, S and R, respectively. In the crystal, mol-ecules are linked into infinite chains along [010] by O-H?O hydrogen bonds. C?O [3.306?(2)-3.347?(2)?Å] short contacts and C-H?? inter-actions also occur.
| S-EPMC3007289 | biostudies-literature
Project description:The title compound, C(28)H(44)O(4)·0.56H(2)O, is a co-crystal of methyl isoeichlerialactone monohydrate as the major component and methyl isoeichlerialactone as the minor component in a 0.55778 (3):0.44222 (3) ratio. The conformations of both components are identical except for that of the -COOCH(3) group of the methyl propanoate side chain on the cyclo-hexane ring which is positionally disordered over two orientations. The mol-ecule of methyl isoeichlerialactone has three fused rings and all rings are trans-fused. The two cyclo-hexane rings are in standard chair conformations and the cyclo-pentane ring adopts an envelope conformation. In the crystal, weak C-H⋯O inter-actions link methyl isoeichlerialactone mol-ecules into screw chains along [010]. The crystal structure is further stabilized by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions.
| S-EPMC3007061 | biostudies-literature
Project description:The title compound, C(33)H(42)O(5), known as xerophenone A {systematic name: (1R,3R,4R,6S,8E,10R)-10-hy-droxy-8-[hy-droxy(phen-yl)methyl-ene]-4-methyl-1,6-bis-(3-methyl-but-2-en-1-yl)-3-(3-methyl-but-3-en-1-yl)-11-oxatricyclo-[4.3.1.1(4,10)]undecane-7,9-dione} is a naturally occurring rearranged benzophenone compound which was isolated from the twigs of Garcinia propinqua. The absolute configuration was determined by refining the Flack parameter to 0.18 (16). The absolute configurations at positions 1, 3, 4, 6 and 10 of the xerophenone A are R, R, R, S and R. In the mol-ecule, the cyclo-hexane-1,3-dione, tetra-hydro-2H-pyran and tetra-hydro-furan rings adopt twisted boat, standard chair and envelope conformations, respectively. The 3-methyl-but-3-en-1-yl substituent is disordered over two sets of sites in a 0.771 (11):0.229 (11) ratio. An intra-molecular O-H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, mol-ecules are linked by O-H⋯O and weak C-H⋯O inter-actions into a chain along the a axis. A very weak C-H⋯π inter-action and C⋯O short contact [2.989 (2) Å] are also present.
| S-EPMC3344568 | biostudies-literature
Project description:THE TITLE ACRIDONE ALKALOID [SYSTEMATIC NAME: 1,3,5-trihydr-oxy-2,4-bis-(3-methyl-but-2-en-yl)acridin-9(10H)-one], C(23)H(25)NO(4), has previously been reported as crystallizing in the chiral ortho-rhom-bic space group P2(1)2(1)2(1) [Chantrapromma et al. (2010 ?). Acta Cryst. E66, o81-o82] but the absolute configuration could not be determined from data collected with Mo radiation. The absolute configuration has now been determined by refinement of the Flack parameter with data collected using Cu radiation. All features of the mol-ecule and its crystal packing are similar to those previously described.
| S-EPMC2979734 | biostudies-literature