A Binary Catalytic System for Enantioselective Annulation of 3-Amino Oxetanes with Isocyanates Leading to Antiviral Chiral 2-Iminothiazolidines

Synergistic effect of a binary ionic liquid/base catalytic system for efficient conversion of epoxide and carbon dioxide into cyclic carbonates

Introduction. Neurotoxicity is one of the specific systemic complications of anticancer chemotherapy. Detection in experimental animals complications of psychotropic or neurotropic action of the new drug is one of the most difficult challenges of preclinical toxicology. Preclinical toxicological study of the effect of a binary catalyst system «tereftal + ascorbic acid» on the central nervous system (CNS). Objective. The prediction of toxic effects of binary catalytic system in clinical application in patients. Materials and methods. The study was conducted on 300 male mice hybrids (CBA х C57 Bl/6J) F1. Have terephtal - russian drug. A binary catalyst system was injected intravenously once at close to the maximum tolerated dose - 50 mg/kg tereftal + 110 mg/kg ascorbic acid and in therapeutic dose - 20 mg/kg tereftal + 44 mg/kg ascorbic acid. The obtained data were compared with a control animal treated with saline solution and with the data of animals treated with one tereftal and one ascorbic acid in equivalent doses. To assess neurotoxicity tests used standard neuropharmacological screening. An assessment of emotional status, muscle tone were undertaken. Behavior was evaluated in the tests «open field» and «aggression». We evaluated the response to pain stimulation, the change in rectal body temperature. Higher integrative brain functions were investigated on the model of the conditioned reflex of passive avoidance. Estimated effect on convulsive readiness of the CNS. Results. The catalytic system changed the general condition of the animals. This was manifested, on the one hand, in the suppression of their overall activity (sluggishness, inactivity until weakness, muscle relaxation, the lowering side, the slowing of breathing), the other - to increase their excitability (when in group, some animals adopted a characteristic aggressive stands, in some cases seizures). These animals were observed exophthalmos, the appearance of the position «frog», posture «praying mouse», the desire to hide. The inhibitory effect of the catalytic system was dose-dependent. Observed inhibition of various forms of behavior, emotional status, decrease in body temperature and pain sensitivity, in the test for aggression - reducing the number of fights, in open field test - locomotor activity suppression. Spontaneous seizures in the provocation corazol binary catalytic system was not strengthened. Conclusion. The obtained data allow to predict toxic effects from the CNS during clinical use of binary catalytic system «tereftal + ascorbic acid»: total confusion, lethargy, physical inactivity, decrease in body temperature, increased anxiety and aggression and, in very rare cases, the occurrence of seizures.

The catalytic performance of rare-earth metal dialkyl complexes in combination with DMAO (dry methylaluminoxane) is explored. In the presence of 60 equivalents of DMAO, the half-sandwich complex (C13H8CH2Ph)Sc(CH2SiMe3)2(THF) (1) is inert for styrene polymerization, but (C5Me4Ph)Sc(CH2C6H4NMe2-o)2 (2) converts 18% styrene into syndiotactic polystyrene. Under the same conditions, the constrained-geometry configuration sandium complex (C13H8CH2Py)Sc(CH2SiMe3)2 (3a) displays extremely high catalytic activity (> 6420 kg·molSc−1 h−1) and perfect syndiospecific (rrrr > 99%) for styrene polymerization, and, in contrast, its lutetium (3b) and yttrium (3c) analogues are nearly inactive. Although the binary catalytic system 3a/DMAO exhibits very low activity for 4-methoxystyrene polymerization, it is an efficient catalyst for the syndioselective polymerization of other styrene derivatives such as 2-methoxystyrene, 4-methylthiostyrene, 4-fluorostyrene, 4-dimethylhydrosilylstyrene, alkyne-susbstituted styrenes and 4-methylstyrene. In addition, the binary system 3a/DMAO can copolymerize ethylene and styrene to give alternating copolymers with a single glass transition at 80 °C and 4 bar ethylene pressures. On increasing styrene feed amount from 20 to 60 mmol, the styrene content slight increases from 48.2 mol% to 53.8 mol%, but the polymerization activity is obviously promoted from 240 to 532 kg molSc–1·h–1.

Binary catalytic systems constructed by porphyrin cobalts(II) with confining nano-region and Zn(OAc)2 for oxygenation of cycloalkanes with O2 in relay mode

To alleviate the environmental problems caused by the excessive emission of CO2, this study designed and synthesized a binary organocatalytic system based on urea-based hydrogen bond donors and polyether ionic liquids based on a cycloaddition reaction that converts CO2 and small-molecule epoxides into cyclic carbonates with high industrial application value. The binary system is based on a polyether ionic liquid, introducing an organic base (to trap and activate CO2), hydrogen bond donor (to activate the epoxide), and nucleophilic reagent unit (to help open the ring of epoxides), with a variety of active sites. In this paper, the effects of the hydrogen bond donor as well as polyether ionic liquids structure on the activity of the binary system were investigated, the optimal HBD/Lewis base binary catalytic system was established, and the cycle life of this binary system was tested.

Polylactide (PLA) is a fully bio‐derived polyester with great biodegradability, biocompatibility, and mechanical properties. Synthesis of stereoregular PLA by highly stereoselective organocatalyzed ring opening polymerization (ROP) of racemic lactide (rac‐LA) at room temperature is challenging despite some important developments in the past few years. In this contribution, two bulky phenyl diphosphazene bases,p‐PDPBandm‐PDPB,were conveniently synthesized by the Staudinger reaction. In combination with different hydrogen‐bond donors such as ureas and squaramides, they could mediate the stereocontrolled ROP ofrac‐LA in THF at room temperature. Semicrystalline PLAs with narrow dispersity and high tacticity (Pmup to 0.84) were successfully synthesized in a well‐controlled manner using phenyl diphosphazene based/urea binary catalytic system. Structural analysis verified the linear structure and high end‐group fidelity of the resulting polymers. Moreover, the minimal transesterification of the polymer backbone proved by the MALDI‐TOF MS analysis indicated the good controllability of the phenyl diphosphazene based binary catalytic system.

In this paper, effect of catalytic configuration on the sensing properties of nanoparticle gas sensitive thick film was investigated. Two types of catalytic configuration, mono and binary, were made on the nanoparticle. In case of mono catalytic system, Pd or Pt catalyst was doped onto the nanoparticle, respectively. In case of binary catalytic system, Pd and Pt was doped simultaneously with concentration ratio of 1:2 to 2:1 onto the nanoparticle. After doping, gas sensitive thick film was printed on alumina substrate and heat-treated at 450 to . Gas sensing properties was evaluated using 500 to 10,000 ppm gas. As a result, gas sensitive thick film with binary catalytic system showed unstable phenomena that the gas sensitivity was changed according to aging time. In contrary, the mono catalytic system showed relatively stable phenomena despite of aging time. Especially, gas sensitive thick film doped with Pt catalyst and heat-treated at showed good sensing properties such as 0.57 of and very small variation within after aging for 5 hours, and response time was very short less than 20 seconds.

The catalyst (N,N‐bis(2,6‐dibenzhydryl‐4‐ethoxyphenyl)butane‐2,3‐diimine)nickel dibromide, a late transition metal catalyst, was prepared and used in ethylene polymerization. The effects of reaction parameters such as polymerization temperature, co‐catalyst to catalyst molar ratio and monomer pressure on the polymerization were investigated. The α‐diimine nickel‐based catalyst was demonstrated to be thermally robust at a temperature as high as 90 °C. The highest activity of the catalyst (494 kg polyethylene (mol cat)−1 h−1) was obtained at [Al]/[Ni] = 600:1, temperature of 90 °C and pressure of 5 bar. In addition, the performance of a binary catalyst using nickel‐ and palladium‐based complexes was compared with that of the corresponding individual catalytic systems in ethylene polymerization. In a study of the catalyst systems, the average molecular weight and molecular weight distribution for the binary polymerization were between those for the individual catalytic polymerizations; however, the binary catalyst activity was lower than that of the two individual ones. The obtained polyethylenes had high molecular weights in the region of 105 g mol−1. Gel permeation chromatography analysis showed a narrow molecular weight distribution of 1.44 for the nickel‐based catalyst and 1.61 for the binary catalyst system. The branching density of the polyethylenes generated using the binary catalytic system (30 branches/1000 C) was lower than that generated using the nickel‐based catalyst (51/1000 C). X‐ray diffraction study of the polymer chains showed higher crystallinity with lower branching of the polymer obtained. Also Fourier transform infrared spectra confirmed that all obtained polymers were low‐density polyethylene.

Polyvinyl alcohol-potassium iodide: An efficient binary catalyst for cycloaddition of epoxides with CO2

The catalytic coupling and polymerization of CO2 and epoxides has been studied for over 50 years. While traditionally dominated by catalytic systems containing cobalt, chromium, and zinc, the use of iron catalysts has emerged in the past 10 years. This review provides an overview of the homogeneous iron-catalyzed transformations of carbon dioxide and epoxides to yield cyclic and/or polycarbonates. It is important to note the potential for cyclic carbonates to be used as monomers for polymer formation via transesterification or by ring-opening polymerization in some cases, e.g., cyclohexene carbonate. Typical catalytic systems are composed of a Lewis acidic iron center and an anionic nucleophilic source, either through an anionic group weakly bound to the metal center or the addition of an external cocatalyst, cooperatively described as a binary catalytic system. This review is divided into two sections: (1) iron catalysts for cyclic carbonates and (2) iron catalysts for polycarbonates. At the end of each section, a table summarizes each catalytic system and the reaction conditions utilized in an attempt to provide a clearer comparison across the literature. Focus is given to highlighting differences in product selectivity, reaction conditions, and relative amounts of cocatalyst used. The use of iron catalysts in CO2/epoxide chemistry has been less explored compared with zinc, cobalt, and chromium catalysts. This review highlights recent examples including iron complexes that deoxygenate epoxides in situ and geometry-dependent selectivity towards either polycarbonate or cyclic carbonate production. Reaction conditions (temperature, CO2 pressure, and amount of nucleophilic cocatalyst) and catalyst structure are all critical in accessing efficient catalysis for polycarbonate formation.

The investigators conducted a preclinical study of the antitumor efficacy of the combined use of an Oxycobalamin-lio (Ox-lio) + Efiter acid-based binary catalytic system (BCS) with radiation and chemoradiation therapy. The incorporation of the BCS Ox-lio + ascorbic acid (Aa), which was used as independent antitumor agents, into a chemoradiation therapy regimen, was shown to lead to biologically important tumor growth suppression throughout the observation and to promote the potentiated therapeutic effect of radiation/chemotherapy. The therapeutic effectiveness of the Ox-lio + Aa BCS used as a modifier is higher than the Efiter + Ac BCS, which seems to be due to its detoxifying activity. The findings suggest the expediency of a clinical trial of the Ox-lio + Ac BCS as a modifier of medical treatments in patients with malignancies.

(E)-1-(4-Methylphenyl)-1,3-butadiene (E-1-MPBD) synthesized via the “Wittig-type” reaction was polymerized with the ternary catalytic system (Flu-NHC)Lu(CH2SiMe3)2/AliBu3/[Ph3C][B(C6F5)4] (Flu-NHC = C13H8CH2CH2(NCHCHN(C6H2Me3-2,4,6)C) to afford a new product containing exclusively trans-3,4 (>99%) units with perfect syndiotacticity (rrrr > 99%). The regio-3,4 tacticity was proved by the IR and NMR (1H and 13C) spectroscopic analyses, while the 3,4-stereotacticity was confirmed by a model polymer with lower regularity (3,4 = 90.9%, rrrr = 49.3%) prepared by the binary catalytic system (Am-NHC)Lu(CH2SiMe3)2/[Ph3C][B(C6F5)4] (Am-NHC = 2,6-iPrC6H3N═C(C6H5)NCH2CH2(NCHCHN(C6H2Me3-2,4,6)C). The trans-planar conformation was uncovered through 2D-NOESY and 13C CPMAS NMR technologies. This represents the first stereo 3,4-syndioselective polymerization of 1,3-dienes achieved by a rare-earth metal based catalyst. Moreover, hydrogenating the resulting polymer gave the highly syndiotactic poly(4-methylphenyl-1-butene),...

Herein, a series of [ONSN]-type iron(III) complexes were synthesized. A binary catalytic system in combination with iron complexes and tetrabutylammonium bromide (TBAB) exhibited high activity for the synthesis of cyclic carbonates from CO2 (1 atm) and terminal epoxides at room temperature. Additionally, single-component iron complexes without using additional TBAB as nucleophiles also showed high activity for the cycloaddition of CO2 and terminal epoxides under 80 °C and 0.5 MPa of CO2. This study demonstrates that single-component iron catalysts provide a competitive alternative to binary catalytic systems for the synthesis of cyclic carbonates from CO2 and epoxides. Mechanistic studies on a single-component iron catalytic system suggest that the temperature serves as a role of responsive switch for controlling the coordination and dissociation of pyridine bearing iron catalysts detected using in situ infrared spectroscopy, and uncoordinated pyridine activates CO2 to form carbamate. Studies of electrospray ionization high-resolution mass spectrometry reveal that an iron center was used as a Lewis acidic site, free halogen anions from the iron center were used as a nucleophilic site, and coordinated pyridine was released from iron complexes to activate CO2.

Supported transition metals oxides and N-hydroxyphthalimide as binary catalytic systems for the liquid-phase oxidation of cumene

Efficient solvent-free fixation of CO2 into cyclic carbonates catalyzed by Bi(III) porphyrin/TBAI at atmospheric pressure