Search results for "Chiral"
showing 10 items of 752 documents
Novel σ1 antagonists designed for tumor therapy: Structure – activity relationships of aminoethyl substituted cyclohexanes
2021
Abstract Depending on the substitution pattern and stereochemistry, 1,3-dioxanes 1 with an aminoethyl moiety in 4-position represent potent σ1 receptor antagonists. In order to increase the stability, a cyclohexane ring first replaced the acetalic 1, 3-dioxane ring of 1. A large set of aminoethyl substituted cyclohexane derivatives was prepared in a six-step synthesis. All enantiomers and diastereomers were separated by chiral HPLC at the stage of the primary alcohol 7, and their absolute configuration was determined by CD spectroscopy. Neither the relative nor the absolute configuration had a large impact on the σ1 affinity. The highest σ1 affinity was found for cis-configured benzylamines…
Hirālu piridīna organokatalizatoru izstrāde un pielietojums
2015
Maģistra darba ietvaros tika izstrādāta hirālu DMAP organokatalizatoru sintēze. Iegūto organokatalizatoru aktivitāte tika pārbaudīta tetrazola hemiaminālu dinamiskajā kinētiskajā sadalīšanā.
s-wave charmed baryon resonances from a coupled-channel approach with heavy quark symmetry
2009
We study charmed baryon resonances which are generated dynamically within a unitary meson-baryon coupled channel model that treats the heavy pseudoscalar and vector mesons on equal footing as required by heavy-quark symmetry. It is an extension of recent SU(4) models with t-channel vector meson exchanges to a SU(8) spin-flavor scheme, but differs considerably from the SU(4) approach in how the strong breaking of the flavor symmetry is implemented. Some of our dynamically generated states can be readily assigned to recently observed baryon resonances, while others do not have a straightforward identification and require the compilation of more data as well as an extension of the model to d-w…
Properties of D and D-* mesons in the nuclear medium
2009
We study the properties of D and D-* mesons in nuclear matter within a simultaneous self-consistent coupled-channel unitary approach that implements heavy-quark symmetry. The in-medium solution accounts for Pauli blocking effects and for the D and D-* self-energies in a self-consistent manner. We pay special attention to renormalization of the intermediate propagators in the medium beyond the usual cutoff scheme. We analyze the behavior in the nuclear medium of the rich spectrum of dynamically generated baryonic resonances in the C=1 and S=0 sector and their influence on the self-energy and, hence, the spectral function of D and D-* mesons. The D meson quasiparticle peak mixes with Sigma(c)…
One-dimensional oxalato-bridged heterobimetallic coordination polymers by using [the [Cr(pyim)(C2O4)2]− complex as metalloligand [pyim = 2-(2′-pyridy…
2019
Abstract Four new coordination polymers based on the use of the [Cr(pyim)(C2O4)2]− species as a metalloligand, namely [LiCr(pyim)(C2O4)2(MeOH)]n (1), {[CaCr2(pyim)2(C2O4)4]·2MeOH}n (2), {[SrCr2(pyim)2(C2O4)4(H2O)]·0.45MeOH·4.55H2O}n (3) and {[CdCr2(pyim)2(C2O4)4]·MeOH}n (4) [pyim = 2-(2′-pyridyl)imidazole] have been synthesized and characterized by elemental analyses, IR spectra and X-ray diffraction on single crystals. Complex 1 is a neutral heterobimetallic chain where the tris(chelated) chromium(III) unit acts as a bis-bidentate ligand towards {Li(MeOH)}+ fragments through its two oxalate ligands, each lithium ion being five-coordinate in a intermediate surrounding between square pyramid…
Chiral α-P,N Ligands From a Diastereoselective Ph2PH Addition to (η6-Benzaldimine)tricarbonylchromium Complexes
1999
International audience; Chiral α-aminophosphane (α-P–C–N) ligands have been prepared by reversible addition of Ph2PH to tricarbonylchromium benzaldimine complexes (CO)3Cr[η6-o-C6H4(Y)(CH=NR)] (with Y, R = CH3, CH3 or CH2COOCH3; CH3O, CH3 or p-CH3OC6H4; Cl, C6H5), with complete diastereoselectivity. These complexes are stabilized in solution by electron-withdrawing group(s) on the imine.
Synthesis of 8-aminomorphans with high KOR affinity
2021
2-Azabicyclo[3.3.1]nonanes (morphans) with a (3,4-dichlorophenyl)acetyl group at 2-position and a pyrrolidino moiety at 8-position were designed as conformationally restricted analogs of piperidine-based KOR agonists. The synthesis started with 4-oxopiperidine-2-carboxylic acid comprising 13 reaction steps. At first the ketone 10 was transformed into diester 7 bearing a propionate side chain. Dieckmann condensation of diester 7 to afford bicyclic enolester 14 and subsequent Krapcho deethoxycarbonylation represent the key steps of the synthesis. The enantiomeric pyrrolidines (1S,5R,8R)-5a and (1R,5S,8S)-5a were separated by chiral HPLC. The eutomer (1S,5R,8R)-5a showed high KOR affinity (K-i…
Chirality and electronic structure of the thiolate-protected Au38 nanocluster.
2010
Structural, electronic, and optical properties of the thiolate-protected Au(38)(SR)(24) cluster are studied by density-functional theory computations (R = CH(3) and R = C(6)H(13)) and by powder X-ray crystallography (R = C(12)H(25)). A low-energy structure which can be written as Au(23)@(Au(SR)(2))(3)(Au(2)(SR)(3))(6) having a bi-icosahedral core and a chiral arrangement of the protecting gold-thiolate Au(x)(SR)(y) units yields an excellent match between the computed (for R = C(6)H(13)) and measured (for R = C(12)H(25)) powder X-ray diffraction function. We interpret in detail the electronic structure of the Au(23) core by using a particle-in-a-cylinder model. Although the alkane thiolate l…
Enhanced Surface Ligands Reactivity of Metal Clusters by Bulky Ligands for Controlling Optical and Chiral Properties.
2021
Surface ligands play critical roles in determining the surface properties of metal clusters. However, modulating the properties and controlling the surface structure of clusters through surface‐capping agent displacement remain a challenge. In this work, a silver cluster, [Ag 14 (SPh(CF 3 ) 2 ) 12 (PPh 3 ) 4 (DMF) 4 ] ( Ag 14 ‐DMF , where HSPh(CF 3 ) 2 is 3,5‐bis(trifluoromethyl)benzenethiol, PPh 3 is triphenylphosphine and DMF is N,N‐Dimethylformamide), with weakly coordinated DMF ligands on the surface silver sites, was synthesized by using a mixed ligands strategy (bulky thiolates, phosphines and small solvents). The as‐prepared Ag 14 ‐DMF is a racemic mixture of chiral molecules. Owing …
Catalytic Enantioselective Addition of Me2Zn to Isatins
2017
Chiral α-hydroxyamide L5 derived from (S)-(+)-mandelic acid catalyzes the enantioselective addition of dimethylzinc to isatins affording the corresponding chiral 3-hydroxy-3-methyl-2-oxindoles with good yields and er up to 90:10. Furthermore, several chemical transformations were performed with the 3-hydroxy-2-oxindoles obtained.