Tag: M.W:300-400

Application of 14187-32-7, An article , which mentions 14187-32-7, molecular formula is C20H24O6. The compound – Dibenzo-18-crown-6 played an important role in people’s production and life.

Nuclear magnetic resonance and ab initio theoretical studies of 18-crown-6, benzo- and dibenzo-18-crown-6 and their alkali-metal complexes

The formation of alkali-metal ion complexes with the crown ethers, 18-crown-6(18c6), benzo-18c6 and dibenzo-18c6 has been investigated. Theoretical studies of structural changes on complexation, binding energies and changes in electron distribution have been carried out using ab initio quantum theoretical methods. A complementary study of the NMR chemical shifts and coupling constants has also been used to obtain information on complexation and structural changes. The overall views of the structural changes and their relation to ion selectivity as determined by the theoretical and NMR investigations are in agreement. In most cases the structural parameters found bear a close relation to those obtained in crystallographic work on the complexes, where such results are available. An attempt has been made to include solvent effects in aqueous solution by computing the energy of the reaction in which some water molecules in the coordination shell of the metal ion are replaced by the crown ether. When this is done, the ion selectivity sequence predicted from the theoretical work is in conformity with existing (incomplete) experimental data.

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Application of 185449-80-3, An article , which mentions 185449-80-3, molecular formula is C22H18NO2P. The compound – (S)-N,N-Dimethyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine played an important role in people’s production and life.

alpha-Phenylethylamine based chiral phospholidines; new agents for the determination of the enantiomeric excess of chiral alcohols, amines and thiols by means of 31P NMR

The synthesis and application of two new trivalent phosphorus derivatizing agents, based upon (S)-alpha-phenylethylamine, for the enantiomeric excess determination of alcohols, amines and thiols using 31P NMR, is presented.

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Hollow circular compound-based inclusion complexes of an ionic liquid

Inclusion complex formation between hollow circular compounds, e.g. crown ethers, and an ionic liquid, 1-methyl-3-octylimidazolium tetrafluoroborate, in acetonitrile solvent is studied by means of conductivity measurements, IR spectra and NMR spectra. The results reveal the formation of 1 : 1 complexes between the crown ethers and ionic liquid molecules in acetonitrile. Crown ether complexes with electron-deficient imidazolium cations are formed by H-bond formation between the acidic protons of the imidazolium ring of the ionic liquid and the lone pair of electrons of the crown oxygen atom. In the case of dibenzo-18-crown-6, complexation is caused by H-bonding; however, pi-stacking or charge-transfer interactions also appear to have minor contributions to the complex formation. Thus, hydrogen bonding is mainly responsible for the complexation, and ion-dipole interactions also may be responsible for complex formation between ionic liquid molecules and the crown ethers. The interactions in the complexation are analyzed and discussed.

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Catalytic Asymmetric Radical Diamination of Alkenes

Catalytic asymmetric diamination of alkenes is a highly attractive method for creating chiral vicinal diamines, which are ubiquitous in biologically active molecules and versatile ligands as well as organocatalysts. We report the use of O-acylhydroxylamines as dialkylaminyl radical precursors to trigger asymmetric diamination of alkene under Cu(I)/chiral phosphoric acid dual catalysis. This reaction allows for direct alkylamine incorporation and features high enantioselectivity, a broad substrate scope, wide functional-group tolerance, and mild reaction conditions, providing convenient and practical access to a wide range of highly enantio-enriched beta-alkylamine-containing pyrrolidines. We have also achieved asymmetric azidoamination of alkenes by using azidoiodinane as an azidyl radical precursor, offering a complementary method for preparing diverse chiral beta-amino pyrrolidines. The application of the resultant alpha-tertiary pyrrolidine-derived diamine was showcased to significantly promote the enantioselectivity of an asymmetric Michael reaction. Chiral vicinal diamines are characteristic and essential motifs embedded in numerous biologically active molecules. In addition, they are also the core scaffolds for a diverse range of chiral ligands, organocatalysts, and auxiliaries widely used in organic synthesis. For their preparation, asymmetric diamination of readily available alkenes constitutes an expedient and important method for accessing enantio-enriched vicinal diamines. However, none of the known strategies are able to directly introduce a protection-free alkyl amine moiety, mainly because of its strong coordination capability, mostly leading to transition-metal catalyst poisoning and susceptibility to oxidation. As a consequence, both the step economy and amine scope are compromised, thus limiting broad applicability. Here, we report the asymmetric radical diamination of alkenes under Cu(I)/chiral phosphoric acid dual catalysis, enabling direct incorporation of alkyl amine groups. Liu and colleagues describe the asymmetric radical diamination of alkenes triggered by intermolecular addition of dialkylaminyl or azidyl radical to the alkene under Cu(I)/chiral phosphoric acid dual catalysis. This reaction enables direct incorporation of alkylamine moieties and provides convenient and practical access to a wide range of highly enantio-enriched beta-alkylamine-containing pyrrolidines. Moreover, the resulting alpha-tertiary pyrrolidine-derived diamine proves to significantly promote the enantioselectivity of an asymmetric Michael reaction.

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Antitumor potential of crown ethers: Structure-activity relationships, cell cycle disturbances, and cell death studies of a series of ionophores

The present paper demonstrates the antiproliferative ability and structure-activity relationships (SAR) of 14 crown and aza-crown ether analogues on five tumor-cell types. The most active compounds were di-tert- butyldicyclohexano-18-crown-6 (3), which exhibited cytotoxicity in the submicromolar range, and di-tert-butyldibenzo-18-crown-6 (5) (IC50 values of ?2 muM). Also, 3 and 5 induced marked influence on the cell cycle phase distribution-strong G1 arrest, followed by the induction of apoptosis. A computational SAR modeling effort offers insight into possible mechanisms of crown ether biological activity, presumably involving penetration into cell membranes, and points out structural features of molecules important for this activity. The results reveal that crown ethers possess marked tumor-cell growth inhibitory activity, the extent of which depends on the characteristics of the hydrophilic macrocylic cavity and the surrounding hydrophobic ring. Our work supports the hypothesis that crown ether compounds inhibit tumor-cell growth by disrupting potassium ion homeostasis, which in turn leads to cell cycle perturbations and apoptosis.

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The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.39648-67-4, Name is (R)-4-Hydroxydinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine 4-oxide, molecular formula is C20H13O4P. In a Article£¬once mentioned of 39648-67-4, Recommanded Product: 39648-67-4

A Br¡ãnsted acid-catalyzed multicomponent reaction for the synthesis of highly functionalized gamma-lactam derivatives

Br¡ãnsted acids catalyze a multicomponent reaction of benzaldehyde with amines and diethyl acetylenedicarboxylate to afford highly functionalized gamma-lactam derivatives. The reaction consists of a Mannich reaction of an enamine to an imine, both generated in situ, promoted by a phosphoric acid catalyst and a subsequent intramolecular cyclization. The hydrolysis of the cyclic enamine substrate can provide enol derivatives and, moreover, a second attack of the amine on the carboxylate can afford amide derivatives. An optimization of the reaction conditions is presented in order to obtain selectively cyclic enamines that can afford the enol species after selective hydrolysis.

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A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, Product Details of 14187-32-7

Electrochemically synthesized poly(crown-ethers); 13C NMR in the solid state structure determination

This paper deals with 13C NMR in the solid state of electrochemically synthesized doped and undoped poly(DB18C6).NMR spectra are consistent with a poly(triphenylene) structure.In the case of undoped polymers, spectra present lines of tetraalkylammonium cations introduced during the reduction treatment.Results give information about their relative mobility through the solid structure.Keywords: electropolymerization / poly(DB18C6) / 13C NMR spectra in the solid state / tetraalkylammonium cations

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Highly N2-selective coupling of 1,2,3-triazoles with indole and pyrrole

Hydrogen-bond mediated coupling of 1,2,3-triazoles to indoles and pyrroles results in N2 selective functionalization of the triazole moiety in moderate to excellent yields. The reaction was tolerant of un-, mono- and disubstituted triazoles and was applied to synthesize tryptophan derived fluorescent amino acids. Copyright

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Syntheses, structures, and physicochemical properties of diruthenium compounds of tetrachlorocatecholate with metal-metal bonded Ru3+(mu-OR)2Ru3+ and Ru3.5+(mu-OR)2Ru3.5+ Cores (R = CH3 and C2H5)

Metal-metal bonded Ru3+(mu-OR)2Ru3+ and Ru3.5+(mu-OR)2Ru3.5+ (R = CH3 and CH3CH2) compounds with tetrachlorocatecholate (Cl4Cat) have been synthesized in the corresponding alcohol, MeOH and EtOH, from a nonbridged Ru2+-Ru3+ compound, Na3[Ru2(Cl4Cat)4(THF)] ¡¤3H2O¡¤7THF (1). In alcohol solvents, compound 1 is continuously oxidized by oxygen to form Ru3+(mu-OR)2Ru3+ and Ru3.5+(mu-OR)2Ru3.5+ species. The presence of a characteristic countercation leads to selective isolation of either Ru3+(mu-OR)2Ru3+ or Ru3.5+(mu-OR)2Ru3.5+ as a stable adduct species. In methanol, Ph4PCl and dibenzo-18-crown-6-ether afford Ru3+ (mu-OMe)2Ru3+ species, [A]2[Ru2(Cl4Cat)4(mu-OMe) 2Na2(MeOH)6] ([A]+ = Ph4P+ (2), [Na(dibenzo-18-crown-6)(H2O)(MeOH)]+ (3)), while benzo-15-crown-5-ether provides a Ru3.5+ (mu-OMe)2Ru3.5+ species, [Na(benzo-15-crown-5)2][Ru2(Cl4Cat) 4(mu-OMe)2Na2(MeOH)6] (4). The air oxidation of 1 in a MeOH/EtOH mixed solvent (1:1 v/v) containing benzo-15-crown-5-ether provides a Ru3.5+(mu-OMe)2Ru3.5+ species, [Na(benzo-15-crown-5)(H2O)][Ru2(Cl4Cat) 2(mu-OMe)2Na2-(EtOH)2 (H2O)2(MeOH)2]¡¤(benzo-15-crown-5) (5). Similarly, the oxidation of 1 in ethanol with Ph4PCl provides a Ru3.5+(mu-OEt)2Ru3.5+ species, (Ph4P)[Ru2(Cl4Cat)4(mu-OEt) 2Na2(EtOH)6] (7). A selective formation of a Ru3+(mu-OEt)2Ru3+ species, (Ph4P)2[Ru2(Cl4Cat) 4(mu-OEt)2Na2(EtOH)2 (H2O)2] (6), is found in the presence of pyrazine or 2,5-dimethylpyrazine. The crystal structures of these compounds, except 2 and 7, have been determined by X-ray crystallography, and all compounds have been characterized by several spectroscopic and magnetic investigations. The longer Ru-Ru bonds are found in the Ru3+(mu-OR)2Ru3+ species (2.606(1) and 2.628(2) A for 3 and 6, respectively) compared with those of Ru3.5+(mu-OMe)2Ru3.5+ species (2.5260(6) A and 2.514(2) A for 4 and 5, respectively). These structural features and magnetic and ESR data revealed the electronic configurations of sigma2pi2delta*2delta 2pi*2 and sigma2pi2delta*2 delta2pi*1 for Ru3+(mu-OR)2Ru3+ and Ru3.5+(mu-OR)2Ru3.5+, respectively, in which the former is diamagnetic and the latter is paramagnetic with S = 1/2 ground state. Compound 5 forms a one-dimensional chain with alternating arrangement of a Ru3.5+ (mu-OMe)2Ru3.5+ unit and a free benzo-15 -crown-5-ether molecule by intermolecular hydrogen bonds (O(H2O)¡¤¡¤¡¤O(crown-ether) = 2.91-3.04 A). The cyclic voltammetry in DMF affords characteristic metal-origin voltammograms; two reversible and two quasi-reversible redox waves were observed. The feature of cyclic voltammograms for the Ru3+(mu-OR)2Ru3+ species (2, 3, and 6) and the Ru3.5+(mu-OR)2Ru3.5+ species (4 and 7) are similar to each other, indicating that both species are electrochemically stable. The isolation of the pyrazine-trans-coordinated species, [Ph4P][Ru(Cl4Cat)2(L)2] (L = pyrazine (8), 2,5-dimethylpyrazine (9)), revealed the selective isolation of 6 from pyrazine-containing solution. UV-vis spectral variation by ethanolysis for 9 demonstrated the selective conversion from the pyrazine-trans-coordinated species to the Ru3+(mu-OEt)2Ru3+ species without an oxidation to the Ru3.5+(mu-OEt)2Ru3.5+ species. This result suggests the presence of equilibrium between [Ru(Cl4Cat)2(L)2]- and Ru3+(mu-OEt)2Ru3+ species in the synthetic condition for 6.

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In an article, published in an article, once mentioned the application of 14187-32-7, Name is Dibenzo-18-crown-6,molecular formula is C20H24O6, is a conventional compound. this article was the specific content is as follows.SDS of cas: 14187-32-7

Crown Ethers as Guests of Cyclotetrachromotropylene in Water

The three crown ethers, 15-crown-5, 18-crown-6 and dibenzo<18>crown-6-, formed inclusion complexes with the cyclic tetramer host, cyclotetrachromotropylene, in water. Their stability constants K are 830, 510, and 8000 M-1 respectively at 25 deg C.

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