311-28-4Relevant academic research and scientific papers
Chiral benzimidazole derived bis-phenyl triazoles as chiroptical sensors for iodide and chiral amines
John, Marina E.,Karnik, Anil V.
supporting information, p. 2844 - 2853 (2020/05/25)
A series of chiral 2-hydroxy ethyl/benzyl benzimidazole based aryl triazole tweezers have been prepared using click chemistry in high yields. Chiral pool strategy has been used to obtain the benzimidazole-based tweezers in very high enantiomerically enriched form. The aryl triazole tweezers, S-(?)-5a and S-(+)-8a displayed a high degree of selectivity for iodide anion over other anions, including other halides. The aryl triazole tweezers, S-(?)-5a and S-(+)-8a display significant enantio-discrimination for chiral amines. The chiral recognition studies were carried out using UV and circular dichroism (CD) spectroscopy. NMR analysis has been used for establishing the sites for ligation of the iodide anion.
Lewis Acidity Scale of Diaryliodonium Ions toward Oxygen, Nitrogen, and Halogen Lewis Bases
Legault, Claude Y.,Mayer, Robert J.,Mayr, Herbert,Ofial, Armin R.
supporting information, (2020/03/13)
Equilibrium constants for the associations of 17 diaryliodonium salts Ar2I+X- with 11 different Lewis bases (halide ions, carboxylates, p-nitrophenolate, amines, and tris(p-anisyl)phosphine) have been investigated by titrations followed by photometric or conductometric methods as well as by isothermal titration calorimetry (ITC) in acetonitrile at 20 °C. The resulting set of equilibrium constants KI covers 6 orders of magnitude and can be expressed by the linear free-energy relationship lg KI = sI LAI + LBI, which characterizes iodonium ions by the Lewis acidity parameter LAI, as well as the iodonium-specific affinities of Lewis bases by the Lewis basicity parameter LBI and the susceptibility sI. Least squares minimization with the definition LAI = 0 for Ph2I+ and sI = 1.00 for the benzoate ion provides Lewis acidities LAI for 17 iodonium ions and Lewis basicities LBI and sI for 10 Lewis bases. The lack of a general correlation between the Lewis basicities LBI (with respect to Ar2I+) and LB (with respect to Ar2CH+) indicates that different factors control the thermodynamics of Lewis adduct formation for iodonium ions and carbenium ions. Analysis of temperature-dependent equilibrium measurements as well as ITC experiments reveal a large entropic contribution to the observed Gibbs reaction energies for the Lewis adduct formations from iodonium ions and Lewis bases originating from solvation effects. The kinetics of the benzoate transfer from the bis(4-dimethylamino)-substituted benzhydryl benzoate Ar2CH-OBz to the phenyl(perfluorophenyl)iodonium ion was found to follow a first-order rate law. The first-order rate constant kobs was not affected by the concentration of Ph(C6F5)I+ indicating that the benzoate release from Ar2CH-OBz proceeds via an unassisted SN1-type mechanism followed by interception of the released benzoate ions by Ph(C6F5)I+ ions.
Silver (I) activated quaternization of tertiary amines by alkyl iodides: Overall analysis coupling homogeneous and heterogeneous processes
Santos, M. Soledade C.S.,Barbosa, Ester F.G.
experimental part, p. 106 - 113 (2012/04/17)
Kinetic data for the silver (I) activated homogeneous and heterogeneous quaternization of tributylamine by alkyl iodides in toluene is presented. Silver iodide was used as a solid catalyst. Solution and surface parameters were obtained applying the multistep kinetic model, previously proposed by Santos and Barbosa. A scrutiny of the derived quantities evidences competing structural and electronic effects. The solution reaction is dominated by structural factors while electronic effects govern the surface process. An overall analysis considering data from triethylamine systems, earlier investigated, allowed the establishment of a parallelism between the homogeneous and heterogeneous processes. A molecular level study involving size, shape and orientation of the chemical species on the surface, lead to estimates of interfacial layer thicknesses. A combination of surface parameters superficial reacting monolayer thicknesses and, the parallelism between homogeneous and heterogeneous catalysis consented the evaluation of "volumetric surface rate constants" which are directly comparable with their solution counterparts.
The triple role of fluoride ions in palladium-catalyzed Suzuki-Miyaura reactions: Unprecedented transmetalation from [ArPdFL2] complexes
Amatore, Christian,Jutand, Anny,Leduc, Gaatan
, p. 1379 - 1382 (2012/03/27)
Fluoride ions play three roles in the Suzuki-Miyaura reaction. They favor the reaction by formation of trans-[ArPdF(PPh3)2], which reacts with Ar B(OH)2 in an unprecedented rate-determining transmetalation, and by promoting the reductive elimination from the trans-[ArPdAr (PPh3)2] intermediate. Conversely, F - disfavors the reaction by formation of unreactive anionic Ar B(OH)n-3Fn- (n=1-3), leading to two antagonistic effects of F- in the transmetalation. Copyright
The 2-indenylidene chloropalladate {PdCl[Ind(Ph2P=S) 2]}(n Bu4N): A versatile pincer complex with "innocent" and "noninnocent" behavior
Oulie, Pascal,Nebra, Noel,Ladeira, Sonia,Martin-Vaca, Blanca,Bourissou, Didier
experimental part, p. 6416 - 6422 (2012/01/31)
The chloropalladate pincer complex {PdCl[Ind(Ph2P=S) 2]}(nBu4N) (2) has been prepared, and its reactivity has been thoroughly investigated. Alkyl halides such as iodomethane and benzyl chloride react at the electron-rich 2-indenylidene moiety, leading to the 2-indenyl pincer complexes {PdI[Ind(Me)(Ph2P=S)2]} (3) and {PdCl[Ind(Bn)(Ph2P=S)2]} (4), respectively. The ligand backbone is also involved in the reaction of 2 with the electron-deficient alkyne MeCO2C≡CCO2Me. Formally, one of the pincer ligand side arms is elongated and the original complex 5, featuring three fused metallacycles, is obtained. Nucleophiles such as PPh3 and NHCy 2 also react readily with 2, to give the corresponding 2-indenylidene complexes by displacement of the chloride at Pd. In addition, treatment of 2 with PhC≡CLi affords {Pd(C≡CPh)[Ind(Ph2P=S) 2]}(nBu4N) (8), the first alkynylpalladate to be isolated. All the new compounds have been characterized by multinuclear NMR spectroscopy and mass spectrometry. The structures of complexes 3, 5, and 8 have been further analyzed by means of X-ray diffraction studies.
Distinguishing between pathways for transmetalation in Suzuki-Miyaura reactions
Carrow, Brad P.,Hartwig, John F.
supporting information; experimental part, p. 2116 - 2119 (2011/04/23)
We report a systematic study of the stoichiometric reactions of isolated arylpalladium hydroxo and halide complexes with arylboronic acids and aryltrihydroxyborates to evaluate the relative rates of the two reaction pathways commonly proposed to account for transmetalation in the Suzuki-Miyaura reaction. On the basis of the relative populations of the palladium and organoboron species generated under conditions common for the catalytic process and the observed rate constants for the stoichiometric reactions between the two classes of reaction components, we conclude that the reaction of a palladium hydroxo complex with boronic acid, not the reaction of a palladium halide complex with trihydroxyborate, accounts for transmetalation in catalytic Suzuki-Miyaura reactions conducted with weak base and aqueous solvent mixtures.
TRICYCLIC FUSED HETEROCYCLE COMPOUNDS, PROCESS FOR PREPARING THE SAME AND USE THEREOF
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Example 165, (2010/01/31)
Compounds represented by formula (1),???whereinX is, for example, CH, CH2, CHR (wherein R is a lower alkyl group or a substituted lower alkyl group) or CRR' (wherein R and R' are the same as the above defined R);Y is, for example, CH, CH2or C=O;Z is, for exampe, O, S, S=O or SO2;U is C or N;R1to R4are each independently, for example, a hydrogen atom, OR, SR (wherein R is the same as defined above), or an aromatic ring, a substituted aromatic ring or a heterocycle;???at least one of R5and R8is, for example, OH and the remaining of R5and R8are each independently, for example, a hydrogen atom or OH, optical isomers thereof, conjugates thereof or pharmaceutically acceptable salts thereof are provided. These compounds are characterized in having a wide range of pharmacological actions such as an excellentrelaxing action of tracheal smooth muscles, an inhibition of airway hypersensitivity and an inhibition of infiltration of inflammatory cells into the airway and, in addition, high safety.
An unusual Michael addition-dealkylation or elimination via the reaction of tertiary or secondary amines with a (Z)-iodoacrylate
Maw, Graham,Thirsk, Carl,Whiting, Andrew
, p. 8387 - 8390 (2007/10/03)
A series of (E)-ammonium or amino acrylates have been prepared via the Michael addition of methyl (Z)-iodoacrylate and several secondary and tertiary alkylamines. Tertiary amines undergo concomitant addition-dealkylation, almost quantitatively producing (
An azophenol-based chromogenic anion sensor
Lee, Dong Hoon,Lee, Kwan Hee,Hong, Jong-In
, p. 5 - 7 (2007/10/03)
(equation presented) A new chromogenic azophenol-thiourea based anion sensor, 2, has been developed. This system allows for the selective colorimetric detection of F-, H2PO4-, and AcO-. Selectivity trends turned out to be dependent upon guest basicity and conformational complementarity between 2 and the guest.
Aza crown ether calix[4]arenes containing cation and anion binding sites: Effects of metal ions towards anion binding ability
Tuntulani, Thawatchai,Poompradub, Sirilux,Thavornyutikarn, Praput,Jaiboon, Nongnuj,Ruangpornvisuti, Vithaya,Chaichit, Narongsak,Asfari, Zouhair,Vicens, Jacques
, p. 5541 - 5544 (2007/10/03)
Tripodal aza crown ether calix[4]arenes containing both cation and anion binding sites (5a and 5b) have been synthesized. The X-ray analysis shows that 5a forms a self-threaded rotaxane-like structure in the solid state. 1H NMR titrations of the two ligands with various halide anions indicate that 5a and 5b can form complexes with Br- and I- but not F-. However, both compounds form more stable complexes with I- than with Br- in the presence of Bu4N+. The presence of K+ enhances the binding ability of 5a towards Br-.
