5097-93-8Relevant articles and documents
Does a Stilbazolium Cation Adsorbing Poly(styrenesulfonate) Anion Form Micellelike Clusters?
Takagi, Katsuhiko,Fukaya, Haruhiko,Sawaki, Yasuhiko
, p. 7469 - 7472 (1988)
Poly(styrenesulfonate) anion (PSSn-) is shown to aggregate with a large number of stilbazolium cations (Stz+) which undergo an electron-relay chain photoisomerization in the presence of Ru(bpy)32+ sensitizer.The quantum yields for the cis-to-trans isomerization Φc-->t were rather constant in the range of 50 - 110, irrespective of changing the solvent from water to acetone or of the degrees of polymerization of PSSn- from 100 to 5000.Adsorbtion and aggregation numbers of benzyltrimethylammonium ion (BTA+), an organic cationic substitute for Stz+, on PSSn- were determined by a methylanthracene quenching method.The results show that the thousands of Stz+ ions bound to PSSn- are divided into small aggregates of micellelike clusters and that their aggregation numbers are constant in the range of 80 - 90, irrespective of the degree of polymerization of PSSn-.It was concluded that the electron-relay chain isomerization proceeds within one micellar cluster.
Visible Photosensitization of trans-Styrylpyridine Coordinated to fac-[Re(CO)3(dcbH2)]+: New Insights
Matos, Lais S.,Amaral, Ronaldo C.,Murakami Iha, Neyde Y.
, p. 9316 - 9326 (2018)
A strategic methodology has been developed to effectively synthesize the fac-[Re(CO)3(dcbH2)(trans-stpy)]+ complex, where dcbH2 = 2,2′-bipyridine-4,4′-dicarboxylic acid and trans-stpy = trans-4-styrylpyridine, which has been designed to efficiently absorb visible light. The complex exhibits outstanding trans-to-cis photoisomerization with 436 nm irradiation (φtrans→cis = 0.50 ± 0.03), in contrast to the photochemical behavior previously reported in the literature (Faustino, L. A.; et al. Inorg. Chem. 2018, 57, 2933-2941). The main emphasis here is to address the synthetic strategy for obtaining the actual complex, its characterization, and an accurate description of its photochemical and photophysical behavior, which reveal new insights into this complex.
Mechanistic Aspects of Aryl-Halide Oxidative Addition, Coordination Chemistry, and Ring-Walking by Palladium
Zenkina, Olena V.,Gidron, Ori,Shimon, Linda J. W.,Iron, Mark A.,Van Der Boom, Milko E.
, p. 16113 - 16125 (2015)
This contribution describes the reactivity of a zero-valent palladium phosphine complex with substrates that contain both an aryl halide moiety and an unsaturated carbon-carbon bond. Although η2-coordination of the metal center to a C=C or C≡C unit is kinetically favored, aryl halide bond activation is favored thermodynamically. These quantitative transformations proceed under mild reaction conditions in solution or in the solid state. Kinetic measurements indicate that formation of η2-coordination complexes are not nonproductive side-equilibria, but observable (and in several cases even isolated) intermediates en route to aryl halide bond cleavage. At the same time, DFT calculations show that the reaction with palladium may proceed through a dissociation-oxidative addition mechanism rather than through a haptotropic intramolecular process (i.e., ring walking). Furthermore, the transition state involves coordination of a third phosphine to the palladium center, which is lost during the oxidative addition as the C-halide bond is being broken. Interestingly, selective activation of aryl halides has been demonstrated by adding reactive aryl halides to the η2-coordination complexes. The product distribution can be controlled by the concentration of the reactants and/or the presence of excess phosphine.
Lewis Acid Promoted Trapping of Chiral Aza-enolates
Lanza, Francesco,Pérez, Juana M.,Jumde, Ravindra P.,Harutyunyan, Syuzanna R.
, p. 1253 - 1262 (2019)
We present a study on sequential conjugate addition of Grignard reagents to alkenyl-heteroarenes followed by trapping of the resulting enolates, yielding moderate to good diastereoselectivities. Contrary to conventional wisdom, one-pot conjugate addition/trapping using two reactive Michael acceptors in combination with Grignard reagents can proceed via conjugate addition to the least reactive Michael acceptor. This unusual chemoselectivity is triggered by the presence of a Lewis acid, reverting the usual reactivity order of Michael acceptors.
A new insight into the push-pull effect of substituents via the stilbene-like model compounds
Cao, Chaotun,Cao, Chenzhong,Zeng, Zhao
, (2022/02/01)
In this paper, authors report on 1-pyridyl-2-arylethenes, 1-furyl-2-arylethylenes, 1,2-diphenylpropylenes and substituted cinnamyl anilines as stilbene-like model compounds to investigate the factors dominating the push-pull effect of substituents via usi
A Solid-Phase Assisted Flow Approach to In Situ Wittig-Type Olefination Coupling
Aldrich-Wright, Janice R.,Dankers, Christian,Gordon, Christopher P.,Polyzos, Anastasios,Tadros, Joseph
supporting information, p. 4184 - 4194 (2021/08/24)
Described herein is the development of a continuous flow, solid-phase triphenylphosphine (PS-PPh3) assisted protocol to facilitate the in situ coupling of reciprocal pairs of halogen and carbonyl functionalised molecular pairs by a Wittig olefination within 15 mins. The protocol entails injecting a single solution (1 : 1 CHCl3 : EtOH) containing the halogenated and carbonyl-based substrates into a continuously flowing stream of CHCl3 : EtOH (1 : 1), passed through a fixed bed of K2CO3 and PS-PPh3. With advancement to the previous PS-PPh3 coupling procedures, the method employs a traditional polystyrene-based immobilisation matrix, the substrate scope of the protocol extended to substituted ketones, secondary alkyl chlorides, and an unprotected maleimide scaffold.
Determination and application of the excited-state substituent constants of pyridyl and substituted phenyl groups
Cao, Chao-Tun,Yan, Lu,Cao, Chenzhong
, (2021/05/21)
Thirty six 1-pyridyl-2-arylethenes XCH=CHArY (abbreviated XAEY) were synthesized, in which, X is 2-pyridyl, 3-pyridyl and 4-pyridyl and Y is OMe, Me, H, Br, Cl, F, CF3, and CN. Their ultraviolet absorption spectra were measured in anhydrous ethanol, and their wavelengths of absorption maximum λmax were recorded. Also, the 234 λmax values of 1-substituted phenyl-2-arylethylene compounds (XAEY, where X is substituted phenyl) were collected. The excited-state substituent constants (Formula presented.) of three pyridyl groups and 23 substituted phenyl groups (total of 26) were obtained by means of curve-fitting method. Taking the λmax values of 358 samples of bi-arylethene derivatives as a data set and 126 samples of bi-aryl Schiff bases (including nine compounds synthesized by this work) as another data set, quantitative correlation analyses were performed by employing the obtained (Formula presented.) as a parameter, and good results were obtained for the two data sets. The reliability of the obtained (Formula presented.) values was verified. The results of this paper can provide excited-state substituent constants for the study and application of optical properties of conjugated organic compounds containing aryl groups.
Copper(0) nanoparticle catalyzed Z-Selective Transfer Semihydrogenation of Internal Alkynes
Moran, Maria Jesus,Martina, Katia,Bieliunas, Vidmantas,Baricco, Francesca,Tagliapietra, Silvia,Berlier, Gloria,De Borggraeve, Wim M.,Cravotto, Giancarlo
, p. 2850 - 2860 (2021/05/06)
The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investigated as a lead-free alternative to Lindlar catalysts. A stereo-selective methodology for the hydrogenation of internal alkynes to the corresponding (Z)-alkenes in high isolated yields (86% average) has been developed. This green and sustainable transfer hydrogenation protocol relies on non-noble copper nanoparticles for reduction of both electron-rich and electron-deficient, aliphatic-substituted and aromatic- substituted internal alkynes. Polyols, such as ethylene glycol and glycerol, have been proven to act as hydrogen sources, and excellent stereo- and chemoselectivity have been observed. Enabling technologies, such as microwave and ultrasound irradiation are shown to enhance heat and mass transfer, whether used alone or in combination, resulting in a decrease in reaction time from hours to minutes. (Figure presented.).
Deaminative Olefination of Methyl N-Heteroarenes by an Amine Oxidase Inspired Catalyst
Thorve, Pradip Ramdas,Maji, Biplab
supporting information, p. 542 - 547 (2021/01/26)
We explored the bioinspired o-quinone cofactor catalyzed aerobic primary amine dehydrogenation for a cascade olefination reaction with nine different methyl N-heteroarenes, including pyrimidines, pyrazines, pyridines, quinolines, quinoxolines, benzimidazoles, benzoxazoles, benzthiazoles, and triazines. An o-quinone catalyst phd (1,10-phenanthroline-5,6-dione) combined with a Br?nsted acid catalyzed the reaction. N-Heteroaryl stilbenoids were synthesized in high yields and (E)-selectivities under mild conditions using oxygen (1 atm) as the sole oxidant without needing transition-metal salt, ligand, stoichiometric base, or oxidant.
Palladium anchored on guanidine-terminated magnetic dendrimer (G3-Gu-Pd): An efficient nano-sized catalyst for phosphorous-free Mizoroki-Heck and copper-free Sonogashira couplings in water
Khalafi-Nezhad, Ali,Moaddeli, Ali,Niknam, Esmaeil
, (2020/07/25)
In this research, a novel type of Fe3O4&at;silica-supported dendrimer capped by guanidine groups for immobilization of palladium was reported. This novel nano-sized catalyst was characterized by FTIR, TGA, XRD, FESEM, EDX, VSM, XPS and HRTEM methods. Enhanced catalytic activity of the prepared catalyst in Mizoroki-Heck and copper-free Sonogashira coupling reactions were evaluated in water as a green solvent. The influence of the various reaction parameters such as catalyst dosage, time and temperature on two mentioned C–C coupling reactions were studied. Results showed that the catalyst could be easily recovered by simple separation by an external magnet and reused for five cycles of recovery without considerable losing of its activity.
