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Oxirane Ring (oxirane + ring)
Selected AbstractsChemInform Abstract: Tetraaryl-1,3-dioxolane-4,5-dimethanols as Catalysts for the Addition of Trimethylsilyl Cyanide to Benzaldehyde and the Oxirane Ring.CHEMINFORM, Issue 22 2008Yu. N. Belokon Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Asymmetric Synthesis of Isoquinoline Derivatives from Amino AcidsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2005Oxana Sieck Abstract Reaction of isoquinolines 1 with N -arylsulfonylamino acid fluorides 2 provides a highly stereoselective access to new dihydroimidazo[2,1 -a]isoquinolin-3-ones 5 via intermediate N -acylisoquinolinium salts 3. Addition reactions to the en-amine double bond, such as hydrogenation or epoxidation with dimethyldioxirane, leads to tetrahydroimidazo[2,1 -a]isoquinoline-3-ones 6, 7 and oxiranes 8, respectively. Opening of the oxirane ring of the 8 with nucleophiles allows the synthesis of hydroxytetrahydroimidazo[2,1 -a]isoquinolin-3-ones 10 or 12 or of the polycyclic 1,4-dioxane 13 in high stereoselectivity. The regioselectivity of the oxiran ring opening depends on the kind of nucleophile and the conditions. Reaction of dihydroisoquinoline with O -TBDMS-mandelic acid chloride 15 leads to a tetrahydrooxazolo[2,3 -a]isoquinoline 17 with opposite facial selectivity as compared with dihydroimidazo[2,1 -a]isoquinolin-3-ones 5. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Cascade Reactions: Catalytic Synthesis of Functionalized 1,3-Dihydroisobenzofuran and Tetrahydrofuran Derivatives by Sequential Nucleophilic Ring Opening,Heterocyclization, Oxidative Carbonylation of AlkynyloxiranesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Nicola Della Ca' Abstract Differently substituted alkynyloxiranes were efficiently converted into functionalized 1,3-dihydroisobenzofurans and tetrahydrofuran derivatives in fair to good yields by a new cascade reaction, consisting of a sequential nucleophilic ring opening,heterocyclization,oxidative carbonylation process. Reactions were carried out at 80,100,°C and under a 3:1 mixture of carbon monoxide and air (total pressure=32,42,atm at 25,°C) in methanol or acetonitrile/methanol mixtures in the presence of catalytic amounts of palladium diiodide in conjunction with an excess of potassium iodide. The nucleophilic species beginning the cascade process by regioselective attack to the less hindered carbon of the oxirane ring can be methanol itself or iodide anions. [source] Polyurethane networks from different soy-based polyols by the ring opening of epoxidized soybean oil with methanol, glycol, and 1,2-propanediolJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009Cheng-Shuang Wang Abstract A series of polyols with a range of hydroxyl (OH) numbers based on soybean oil and epoxidized soybean oil were prepared by oxirane ring opening with methanol, glycol, and 1,2-propanediol. The polyols, with average functionalities varying from 2.6 to 4.9, were characterized. Novel cast polyurethane resins were synthesized from these polyols and 2,4-toluene diisocyanate. The sol fraction of the network decreased as the OH number of the polyol from which it was synthesized increased. None of the samples were completely soluble. The crosslinking density of the polyurethanes correlated directly with the functionality of the polyols. The thermal and mechanical properties of the cast resins were characterized with differential scanning calorimetry and thermogravimetry. The glass-transition temperature increased with the OH number increasing, and the thermal stability of the resins was slightly decreased with the OH number increasing. The tensile strength at break increased with the OH number increasing. Polyurethanes prepared from polyols with OH numbers higher than 170 mg of KOH/g were glassy, whereas those with OH numbers below that value were rubbery. Glassy polyurethanes displayed decent mechanical strength, whereas rubbery samples showed relatively poor elastic properties and were characterized by lower strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Synthesis of well-defined glycidyl methacrylate based block copolymers with self-activation and self-initiation behaviors via ambient temperature atom transfer radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2007Ping Jiang Abstract Well-defined glycidyl methacrylate (GMA) based di- and triblock copolymers, with self-activation and self-initiation behaviors by incorporation of 2-(diethylamino) ethyl methacrylate (DEA) blocks, were synthesized via ambient temperature atom transfer radical polymerization (ATRP). The stability of the GMA pendant oxirane rings in tertiary amine environments at ambient temperature was investigated. More importantly, both self-activation behavior in oxirane ring opening addition reaction and self-initiation behavior in post-cure oxirane ring opening crosslinking of these block copolymers were evidenced by 1H NMR studies. The results demonstrated that the reactivity of pendent oxirane rings was strongly dependant on the nucleophilicity and steric hindrance of tertiary amine moieties and temperature. This facilitated the synthesis of well-defined block copolymers of GMA and DEA via sequential monomer addition ATRP, particularly for polymerization of GMA monomer at ambient temperature. Moreover, these one-component GMA based block polymers have novel self-activation and self-initiation properties, rendering some potential applications in both enzyme immobilization and GMA-based thermosetting materials. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2947,2958, 2007 [source] Synthesis and characterization of epoxidized polybutadiene/polyaniline graft conducting copolymerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2004F. R. De Risi Abstract In this article the synthesis and characterization of an elastomeric conducting material, obtained by grafting polyaniline (EB) on commercial cis -1,4-polybutadiene (PB), are described. PB was first partially epoxidized in chloroform solution using meta-chloroperbenzoic acid (MCPBA). The conducting polymer was then grafted to the activated polybutadiene (EPB) via the aminolysis reaction between the polyaniline NH2 terminal groups and the oxirane rings. The material so obtained (EPBPAN) and the epoxidized intermediate product were characterized by 1H NMR, 13C NMR, Fourier transform infrared, and ultraviolet,visible spectroscopy, thermal and mechanical analysis, and electrical conductivity measurements. The effect of the sample deformation on conductivity also was analyzed. The HCl doping of the EPBPAN film induced crosslinking reactions, generated by the acid cleavage of unreacted oxirane groups. The electrical conductivity of the doped material reached values of about 10,5 ,,1 cm,1. The key characteristics of our elastomeric conducting material are its simple synthesis, its starting as a commercial product, and the solubility of its undoped form in a common low-boiling organic solvent like chloroform. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3082,3090, 2004 [source] | |||||||||||||