Cyclohexyl Group Research Articles

Synthesis and Characterization of Rhenium(V) Oxo Complexes Bearing PNP-Pincer Ligands

The synthesis of a series of pyridine-based PNP-pincer rhenium-oxo complexes, with phenyl (1, 3), tert-butyl (2), or cyclohexyl (4) groups on the phosphorus atoms and either a ReO2X (1, 2) or a ReCl2O (3, 4) core is reported. The structures of these compounds were characterized using 1H, 13C, and 31P NMR and using X-ray crystallography for 1 and 4. Compounds 2 and 3 crystallize as the corresponding ReO(OH)X compounds upon their reaction with moisture during the crystallization process. The complexes were tested as catalysts in the oxidation reaction of limonene with H2O2, the oxygen atom transfer reaction from pyridine N-oxide to triphenylphosphine, and the dehydration reaction of 1-phenylethanol, but all showed poor catalytic performance. All complexes can be deprotonated at the benzylic arm, and 2 can be deprotonated twice, accompanied by dearomatization of the pyridine ring. 3 and 4 are highly stable in their oxidized forms. The noninnocent behavior shown here could open up possibilities for cooperativ...

Ion-Tagged Phosphines as Ligands for Suzuki Coupling of Aryl Halides in a Phosphonium Ionic Liquid

Gramine-based N-substituted phosphines were synthesized and utilized as ligands in Suzuki–Miyaura coupling of aryl bromides and chlorides in the room temperature ionic liquid trihexyltetradecylphosphonium bis(trifluoromethanesulfonyl)imide. Increased yields were achieved with ion-tagged ligands compared to ligands bearing pendant amines, likely due to higher solubility of the former. Cyclohexyl groups on the phosphine moiety generally resulted in higher yields than tert-butyl groups. In addition, a biphasic ionic liquid/water system outperformed catalysis in neat ionic liquid and provided higher yields at lower temperatures.

Methyl 3,5-bis(cyclohexylmethoxy)benzoate

In the title compound, C22H32O4, the atoms of the methyl ester group and the alk­oxy O atoms are all coplanar with the central aromatic ring, with an r.m.s. deviation of 0.008 Å. Bonds to the methyl­ene and cyclo­hexyl groups are also very close to this plane, so that the mol­ecule is essentially flat, apart from the cyclo­hexyl groups. The mean planes through the cyclo­hexyl groups are tilted by 30.08 (9) and 36.14 (7)° with respect to the central aromatic ring. In the crystal, pairs of mol­ecules linked by C—H⋯O hydrogen bonds form planar units which are stacked along the a axis, with an average inter­planar distance of 3.549 (2) Å. Stacking appears to be stabilized by further weak C—H⋯O hydrogen bonds.

四环二氟甲醚桥键液晶化合物性能研究

Liquid crystalline compounds with difluoromethyleneoxy linkage group are widely used in liquid crystal mixtures.However,their phase behavior and physical properties have not been reported systematically.The mesomorphic properties of two series of compounds 1 and 2 with cyclohexyl group were thoroughly studied by using differential scanning calorimetry(DSC)and polarizing optical microscopy(POM).The effect of all the compounds on the mixtures were systematically investigated and their physical parameters were extropolated by using addition principle.The results show that compounds 1 have higher clearing point and wider nematic phase temperature range than that of compounds 2.Due to the increase of a fluorine atom on the skeleton,compounds 2 have higher dielectric anisotropy than that of compounds 1.Compounds 1 can significantly improve low temperature miscibility and broaden the mixed liquid crystal temperature range.

Evaluation of aminohydantoins as a novel class of antimalarial agents.

Given the threat of drug resistance, there is an acute need for new classes of antimalarial agents that act via a unique mechanism of action relative to currently used drugs. We have identified a set of druglike compounds within the Tres Cantos Anti-Malarial Set (TCAMS) which likely act via inhibition of a Plasmodium aspartic protease. Structure-activity relationship analysis and optimization of these aminohydantoins demonstrate that these compounds are potent nanomolar inhibitors of the Plasmodium aspartic proteases PM-II and PM-IV and likely one or more other Plasmodium aspartic proteases. Incorporation of a bulky group, such as a cyclohexyl group, on the aminohydantion N-3 position gives enhanced antimalarial potency while reducing inhibition of human aspartic proteases such as BACE. We have identified compound 8p (CWHM-117) as a promising lead for optimization as an antimalarial drug with a low molecular weight, modest lipophilicity, oral bioavailability, and in vivo antimalarial activity in mice.

Biodegradable poly (butylene succinate‐co‐cyclohexanedimethylene succinate): Synthesis, crystallization, morphology, and rheology

ABSTRACTPoly (butylene succinate‐co‐cyclohexanedimethylene succinate) (PBCSs), which are composed of various amounts of cyclohexanedimethylene succinate (CS) with butylene succinate (BS) were synthesized via polycondensation. The composition of PBCSs was analyzed by a 1H‐nuclear magnetic resonance (1H‐NMR). Crystallization, morphology, and rheological properties of PBCSs were investigated by a polarized optical microscopy (POM), a differential scanning calorimetry (DSC), a X‐ray diffraction (XRD), and a parallel‐plate rheometer (PPR). The studies revealed that the composition of PBCSs played an important role in controlling their properties. Only one Tg can be seen for PBCSs by DSC, which demonstrate they are miscible copolymers. PBCSs exhibited lower crystallization capacity than its homopolyesters either Poly (butylene succinate) (PBS) or poly (cyclohexanedimethylene succinate) (PCS). It also proved that the cyclohexyl group of CHDM not only affected the crystalline formation, but also changed spherulitic morphology during crystallization. The spherulitic size gradually decreased with an increase of CS content. When CS content approached 50 wt %, the crystallization ability reached minimum. By comparing the effect of temperature with shear rate, it concluded that the viscosities of PBCSs were more sensitive to temperature rather than shear rate, and flow activation energies of PBCSs linearly increased with an increase of CS content. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40103.

The organic–inorganic hybrid material 1-cyclohexylpiperazine-1,4-diium tetrachloridozincate

In the crystal structure of the title organic-inorganic hybrid material, (C10H22N2)[ZnCl4], the tetrachloridozincate anions and 1-cyclohexylpiperazine-1,4-diium dications are interconnected via N-H...Cl and C-H...Cl hydrogen bonds to form layers parallel to the (001) plane. The cyclohexyl groups from adjacent chains interdigitate, thus building the three-dimensional structure. The piperazinium and cyclohexyl rings exhibit regular spatial chair conformations. The title salt was also characterized by FT-IR and Raman spectroscopic analyses.

Binding Interactions between Cucurbit[n]uril Hosts and Tritopic, Dicationic Guests Containing a Central Ferrocenyl and Two Terminal Aminocyclohexyl Sites

The binding interactions between two cucurbit[n]uril hosts (n = 7, 8, CB7 and CB8) and the three new guests 1,1′-bis(cyclohexylammoniomethyl)ferrocene (1H22+), 1,1′-bis(cyclohexylmethylammoniomethyl)ferrocene (2H22+), and 1,1′-bis(cyclohexyldimethylammoniomethyl)ferrocene (32+) were investigated in aqueous solution using 1H NMR spectroscopy, voltammetry, and electrospray (ESI) mass spectrometry. The experimental data reveal that guests 1H22+ and 2H22+ behave similarly with both hosts, leading to the formation of pseudorotaxane complexes in which the host is located centrally around the ferrocenyl residue. A similar complex forms also between 32+ and CB7, but its formation is slower (k = 2.5 × 10–4 s–1) and can be monitored by NMR spectroscopy. Finally, 32+ and CB8 give rise to a ternary 2:1 complex, in which CB8 receptors are bound to the terminal cyclohexyl groups, when the concentration of the host exceeds that of the guest.

One-Pot Synthesis of Substituted Benzo[b]furans from Mono- and Dichlorophenols Using Palladium Catalysts Bearing Dihydroxyterphenylphosphine

A dihydroxyterphenylphosphine bearing cyclohexyl groups on the phosphorus atom (Cy-DHTP) was found to be a powerful ligand for the palladium-catalyzed one-pot synthesis of substituted benzo[b]furans from 2-chlorophenols and terminal alkynes. This catalyst system was also applicable to the sequential one-pot synthesis of disubstituted benzo[b]furans from dichlorophenols via the Suzuki-Miyaura cross-coupling of chlorobenzo[b]furan with boronic acids. The use of two ligands, Cy-DHTP and XPhos, is the key to promoting the reactions. Mechanistic studies suggest that the Pd-Cy-DHTP catalyst is the active species in the Sonogashira cross-coupling step, while the Pd-XPhos catalyst accelerates the Suzuki-Miyaura cross-coupling step.

The DFT study of cyclohexyl hydroxamic acid as a collector in scheelite flotation

In this paper, cyclohexyl hydroxamic acid (CHA) was investigated as a new collector for scheelite flotation by the Density Functional Theory (DFT) calculation, mineral flotation tests, adsorption measurement and zeta potential determination. The DFT computation results indicated that the dianion of CHA or benzoylhydroxamic acid (BHA) exhibited stronger chemical reactivity than their anions and neutral molecules, and that the replacement of phenyl group by cyclohexyl group in BHA molecule significantly impacted the electron donating ability of hydroxamate collectors. In alkaline aqueous solutions, the two oxygen atoms in the dianions of CHA or BHA charged more negative charges than other atoms, and hence became their reactive center. The dianion of CHA exhibited higher atomic charge value, HOMO (Highest Occupied Molecular Orbital) energy, bigger dipole moment and binding energy with Ca2+, thus it had stronger collecting ability for scheelite than that of BHA. In addition, the results of flotation tests, adsorption measurement and zeta potential determination validated that the collecting capability of CHA was stronger than that of BHA, which achieved excellent agreement with computational analysis.

Terminal Alkylphosphanylidene Organo­tantalum(V) Complexes

AbstractThe first terminal organometallic alkylphosphanylidenetantalum(V) complexes [Cp*Ta{1,2‐(NSiMe3)2C6H4}(PR)] were obtained with cyclohexyl (2) and isopropyl groups (3) at phosphorus, whereas adamantyl and tert‐butyl substituents resulted in the formation of the paramagnetic tantalum(IV) complex [Cp*Ta{1,2‐(NSiMe3)2C6H4}Cl] (4). DFT studies showed that the terminal cyclohexyl and isopropyl phosphanylidene complexes are stable towards dimerization and dissociation.

Comparative inhibition of tetrameric carbonyl reductase activity in pig heart cytosol by alkyl 4-pyridyl ketones

Context and objective: The present study is to elucidate the comparative inhibition of tetrameric carbonyl reductase (TCBR) activity by alkyl 4-pyridyl ketones, and to characterize its substrate-binding domain.Materials and methods: The inhibitory effects of alkyl 4-pyridyl ketones on the stereoselective reduction of 4-benzoylpyridine (4-BP) catalyzed by TCBR were examined in the cytosolic fraction of pig heart.Results: Of alkyl 4-pyridyl ketones, 4-hexanoylpyridine, which has a straight-chain alkyl group of five carbon atoms, inhibited most potently TCBR activity and was a competitive inhibitor. Furthermore, cyclohexyl pentyl ketone, which is substituted by cyclohexyl group instead of phenyl group of hexanophenone, had much lower ability to be reduced than hexanophenone.Discussion and conclusion: These results suggest that in addition to a hydrophobic cleft corresponding to a straight-chain alkyl group of five carbon atoms, a hydrophobic pocket with affinity for an aromatic group is located in the substrate-binding domain of TCBR.

Structural requirements for inhibitory effects of bisphenols on the activity of the sarco/endoplasmic reticulum calcium ATPase

Bisphenols (BPs) are a class of small organic compounds with widespread industrial applications. Previous studies have identified several BPs that interfere with the activity of the ion-translocating enzyme sarco/endoplasmic reticulum calcium ATPase (SERCA). In order to define the molecular determinants of BP-mediated SERCA inhibition, we conducted enzyme activity assays with rabbit SERCA to determine the inhibitory potencies of 27 commercially available BPs, which were the basis for structure–activity relationships. The most potent BPs inhibited SERCA at low micromolar concentrations and carried at their two phenyl rings multiple non-polar substituents, such as small alkyl groups or halides. Furthermore, the presence of methyl groups or a cyclohexyl group at the central carbon atom connecting the two phenyl moieties correlated with good potencies. For a characterization and visualization of enzyme/inhibitor interactions, molecular docking was performed, which suggested that hydrogen bonding with Asp254 and hydrophobic interactions were the major driving forces for BP binding to SERCA. Calcium imaging studies with a selection of BPs showed that these inhibitors were able to increase intracellular calcium levels in living human cells, a behavior consistent with that of a SERCA inhibitor.

Chiral Brønsted Acid Catalyzed Enantioselective Synthesis of anti-Homopropargyl Alcohols via Kinetic Resolution-Aldehyde Allenylboration Using Racemic Allenylboronates

The structures for 12 and 13 in the published Scheme 4 were inadvertently drawn incorrectly, with the methyl and cyclohexyl groups transposed in the original structures. The corrected Scheme 4 appears below.

N-Cyclohexyl-3-methylbenzamidine

The title amidine compound, C14H20N2, prepared by a one-pot reaction, is asymmetric as only one N atom has an alkyl substituent. The terminal cyclo­hexyl group connected to the amino N atom is located on the other side of the N—C—N skeleton to the 4-methylbenzene ring and has a chair conformation. The dihedral angle between the phenyl ring and the NCN plane is 47.87 (12)°. In the crystal, mol­ecules are linked via N—H⋯N hydrogen bonds, forming chains propagating along the a-axis direction.

Rheological Bases for Empirical Rules on Shear Viscosity of Lubrication Oils

The shear relaxation spectra of various lubrication oils were measured at 5-205 MHz and 10-70 °C, and the variation of the steady-state shear viscosity (η0) was divided into the contributions of the high-frequency shear modulus (G∞) and relaxation time (τ). The temperature dependence of η0 was dominated by that of τ. The increase in molecular weight accompanies both increase in τ and decrease in G∞, and the increase in η0 results from the larger effect of the former. The flexibility of the chain reduced τ, while its effect on G∞ was rather small. The introduction of phenyl or cyclohexyl groups enhanced G∞. Oils of larger G∞ tend to exhibit a larger temperature dependence of η0.

Unusual stability of reaction intermediates in ortho-metalation reactions of dicyclohexylphenylphosphane with dirhodium(II) tetraacetate

Reaction of dirhodium(II) tetraacetate with 1 molar equivalent of dicyclohexylphenylphosphane afforded the complex [Rh2(μ-O2CCH3)3{μ-(C6H4)PCy2}(CH3COOH)2] (1) in which the phosphane ligand is coordinated to the rhodium atoms in a bridging ortho-metalated mode. As a second product, [Rh2(μ-O2CCH3)3{μ-(C6H4)PCy2}(CH3COOH)(PhPCy2)] (2) was isolated from the same reaction. 2 proved to be unusually stable toward further reaction to a doubly ortho-metalated complex which has been accessible in the reaction of dirhodium(II) tetraacetate with other phosphane ligands. However, doubly ortho-metalated [Rh2(μ-O2CCH3)2{μ-(C6H4)PCy2}2(CH3COOH)2] (4) was isolated in low yield after a prolonged thermal reaction between dirhodium(II) tetraacetate and 2 equivalents of PhPCy2. Exchange of the bridging acetate ligands in 1 and 4 by trifluoroacetate ligands afforded [Rh2(μ-O2CCF3)3{μ-(C6H4)PCy2}(CF3COOH)2] (5) and [Rh2(μ-O2CCF3)2{μ-(C6H4)PCy2}2(CF3COOH)2] (7a). Complex 7a without axial ligands, [Rh2(μ-O2CCF3)2{μ-(C6H4)PCy2}2] (7b) was isolated, as well. The crystal structure of complex 5 was determined showing consequences of the bulky cyclohexyl groups on several structural parameters.

Dioximate‐ and Bis(salicylaldiminate)‐Bridged Titanium and Zirconium Alkoxides: Structure Elucidation by Mass Spectrometry

The treatment of titanium alkoxides with 1,5-pentanedioxime or 2,5-hexanedioxime resulted in the formation of complexes [{TiL(OR)2}2] in which the dioximate ligands (L) bridge a dimeric Ti2(μ2-OR)2 unit. The structures of the complexes were determined by single-crystal structure analysis, ESI mass spectrometry, and 1D and 2D solution NMR spectroscopy. In contrast, the treatment of titanium alkoxides with dioximes bearing cyclic linkers, such as cyclohexyl or aryl groups, resulted in insoluble polymeric compounds. The treatment of various bis(salicylaldiminates) with titanium and zirconium alkoxides resulted in compounds with the same composition [{TiL(OR)2}2], in which, however, two monomeric Ti(OR)2 units are bridged by the ligands L. The two structural possibilities can be distinguished by low-energy collision-induced dissociation owing to their different fragmentation patterns.

Development and Characterization of New Peptidomimetic Inhibitors of the West Nile Virus NS2B–NS3 Protease

A series of new substrate analogue inhibitors of the WNV NS2B-NS3 protease containing decarboxylated arginine mimetics at the P1 position was developed. Among the various analogues, trans-(4-guanidino)cyclohexylmethylamide (GCMA) was identified as the most suitable P1 residue. In combination with dichloro-substituted phenylacetyl groups at the P4 position, three inhibitors with inhibition constants of <0.2 μM were obtained. These GCMA inhibitors have a better selectivity profile than the previously described agmatine analogues, and possess negligible affinity for the trypsin-like serine proteases thrombin, factor Xa, and matriptase. A crystal structure in complex with the WNV protease was determined for one of the most potent inhibitors, 3,4-dichlorophenylacetyl-Lys-Lys-GCMA (K(i)=0.13 μM). The inhibitor adopts a horseshoe-like conformation, most likely due to a hydrophobic contact between the P4 phenyl ring and the P1 cyclohexyl group, which is further stabilized by an intramolecular hydrogen bond between the P1 guanidino group and the P4 carbonyl oxygen atom. These inhibitors are stable, readily accessible, and have a noncovalent binding mode. Therefore, they may serve as suitable lead structures for further development.

Interactions of Cymal-6 and Lipid Vesicles

The solubilization of biological or liposomal membranes, induced by detergents and detergent-like biomolecules, is important to many technical applications and biological phenomena. In fact, the interactions of classical detergents with lipid bilayers are described and understood quite well. Recently, new types of detergents with cyclohexyl groups or branches in their hydrophobic tails have been synthesized and proposed to be superior for membrane protein studies. Cymal-6 has, for example, been used for isolating membrane proteins such as CCR5 and HIV-1 corepressors. Here we provide a rather comprehensive description of the interactions of Cymal-6 with fluid membranes of POPC. This includes the temperature-dependent phase behavior (i.e., the onset and completion of solubilization), membrane partitioning, disordering, and permeabilization as seen using ITC, time-resolved fluorescence anisotropy of DPH, dynamic light scattering, and the lifetime-based vesicle leakage assay.