Search results for "D2"
showing 10 items of 2418 documents
Straightforward Regio- and Diastereoselective Synthesis, Molecular Structure, Intermolecular Interactions and Mechanistic Study of Spirooxindole-Engr…
2021
Straightforward regio- and diastereoselective synthesis of bi-spirooxindole-engrafted rhodanine analogs 5a–d were achieved by one-pot multicomponent [3 + 2] cycloaddition (32CA) reaction of stabilized azomethine ylide (AYs 3a–d) generated in situ by condensation of L-thioproline and 6-chloro-isatin with (E)-2-(5-(4-chlorobenzylidene)-2,4-dioxothiazolidin-3-yl)-N-(2-morpholinoethyl)acetamide. The bi-spirooxindole-engrafted rhodanine analogs were constructed with excellent diastereo- and regioselectivity along with high chemical yield. X-ray crystallographic investigations for hybrid 5a revealed the presence of four contiguous stereocenters related to C11, C12, C19 and C22 of the spiro struct…
Synthesis and Dopamine Receptor Selectivity of the Benzyltetrahydroisoquinoline, (R)-(+)-nor-Roefractine
1998
(R)-(+)-nor-Roefractine (1) was synthesized by the Bischler-Napieralski route, using asymmetric reduction of the 1, 2-didehydro precursor imine with sodium (S)-N-CBZ-prolinyloxyborohydride. Compound 1 was able to displace [3H]-raclopride (a D2 dopamine receptor-selective ligand) from its specific binding sites in rat striatum with selectivity vs [3H]-SCH23390 (D1 dopamine receptor-selective ligand).
Pyrimido[5,4-c]pyrrolo[2,1-a]isoquinoline: a new potential DNA-interactive ring system
2003
The acid catalyzed decomposition of the azide 9 failed to give the title compounds, which were however obtained by a Pschorr-type cyclization on reactive 1-(6-aminopyrimidin-5-yl)-pyrroles of type 13. Derivatives of type 14 and 15 were fully characterized by NMR data. Theoretical calculations demonstrated that the new compounds possess properties suitable for DNA- intercalation.
Antiproliferative properties and g-quadruplex-binding of symmetrical naphtho[1,2-b:8,7-b’]dithiophene derivatives
2021
Background: G-quadruplex (G4) forming sequences are recurrent in telomeres and promoter regions of several protooncogenes. In normal cells, the transient arrangements of DNA in G-tetrads may regulate replication, transcription, and translation processes. Tumors are characterized by uncontrolled cell growth and tissue invasiveness and some of them are possibly mediated by gene expression involving G-quadruplexes. The stabilization of G-quadruplex sequences with small molecules is considered a promising strategy in anticancer targeted therapy. Methods: Molecular virtual screening allowed us identifying novel symmetric bifunctionalized naphtho[1,2-b:8,7-b’]dithiophene ligands as interesting ca…
Dihydroisocoumarins, Naphthalenes, and Further Polyketides from Aloe vera and A. plicatilis: Isolation, Identification and Their 5-LOX/COX-1 Inhibiti…
2021
The present study aims at the isolation and identification of diverse phenolic polyketides from Aloe vera (L.) Burm.f. and Aloe plicatilis (L.) Miller and includes their 5-LOX/COX-1 inhibiting potency. After initial Sephadex-LH20 gel filtration and combined silica gel 60- and RP18-CC, three dihydroisocoumarins (nonaketides), four 5-methyl-8-C-glucosylchromones (heptaketides) from A. vera, and two hexaketide-naphthalenes from A. plicatilis have been isolated by means of HSCCC. The structures of all polyketides were elucidated by ESI-MS and 2D 1H/13C-NMR (HMQC, HMBC) techniques. The analytical/preparative separation of 3R-feralolide, 3′-O-β-d-glucopyranosyl- and the new 6-O-β-d-glucopyranosyl…
Dual Substituent Parameter Modeling of Theoretical, NMR and IR Spectral Data of 5-Substituted Indole-2,3-diones
2002
Correlations of AM1 and PM3 theoretical data, 13C-NMR substituent chemical shifts (13C-SCS) and IR carbonyl group wave numbers [ν(C3â•ÂO)] were studied using dual substituent parameter (DSP) models for 5-substituted indole-2,3-diones. For the C7 atom a reverse substituent effect attributed to extended À-polarization was observed. On the other hand, the DSP approaches for the C3 atom showed normal substituent effects with some contribution of reverse effect supported strongly by 13C-SCS correlations. In the ν(C3â•ÂO) and p(C3â•ÂO) DSP correlations the field effect contribution predominates over the resonance effect, which justifies the using of earlier suggested vibrational cou…
Self-assembly of metallosupramolecular rhombi from chiral concave 9,9'-spirobifluorene-derived bis(pyridine) ligands.
2014
Two new 9,9’-spirobifluorene-based bis(4-pyridines) were synthesised in enantiopure and one also in racemic form. These ligands act as concave templates and form metallosupramolecular [(dppp)2M2L2] rhombi with cis-protected [(dppp)Pd]2+ and [(dppp)Pt]2+ ions. The self-assembly process of the racemic ligand preferably occurs in a narcissistic self-recognising manner. Hence, a mixture of all three possible stereoisomers [(dppp)2M2{(R)-L}2](OTf)4, [(dppp)2M2{(S)-L}2](OTf)4, and [(dppp)2M2{(R)-L}{(S)-L}](OTf)4 was obtained in an approximate 1.5:1.5:1 ratio which corresponds to an amplification of the homochiral assemblies by a factor of approximately three as evidenced by NMR spectroscopy and m…
N-Benzyl Residues as the P1′ Substituents in Phosphorus-Containing Extended Transition State Analog Inhibitors of Metalloaminopeptidases
2020
Peptidyl enzyme inhibitors containing an internal aminomethylphosphinic bond system (P(O)(OH)-CH2-NH) can be termed extended transition state analogs by similarity to the corresponding phosphonamidates (P(O)(OH)-NH). Phosphonamidate pseudopeptides are broadly recognized as competitive mechanism-based inhibitors of metalloenzymes, mainly hydrolases. Their practical use is, however, limited by hydrolytic instability, which is particularly restricting for dipeptide analogs. Extension of phosphonamidates by addition of the methylene group produces a P-C-N system fully resistant in water conditions. In the current work, we present a versatile synthetic approach to such modified dipeptides, based…
Unveiling the Ionic Diels-Alder Reactions within the Molecular Electron Density Theory
2021
The ionic Diels–Alder (I-DA) reactions of a series of six iminium cations with cyclopentadiene have been studied within the Molecular Electron Density Theory (MEDT). The superelectrophilic character of iminium cations, ω >
Valence Topological Charge-Transfer Indices for Reflecting Polarity: Correction for Heteromolecules
2005
Valence topological charge-transfer (CT) indices are applied to the calculation of dipole moments mu. The mu calculated by algebraic and vector semisums of the CT indices are defined. The model is generalized for molecules with heteroatoms and corrected for sp(3)-heteromolecules. The ability of the indices for the description of the molecular charge distribution is established by comparing them with mu of the valence-isoelectronic series of cyclopentadiene, benzene and styrene. Two CT indices, mu(vec) (vector semisum of vertex-pair mu) and mu(vec)V (valence mu(vec)) are proposed. The mu(vec) behaviour is intermediate between mu(vec) and mu(experiment). The correction is produced in the corr…