927-61-7Relevant academic research and scientific papers
Time-Resolved Study of the Solvent and Temperature Dependence of Singlet Oxygen (1Δg) Reactivity toward Enol Ethers: Reactivity Parameters Typical of Rapid Reversible Exciplex Formation
Gorman, A. A.,Gould, I. R.,Hamblett, I.
, p. 7098 - 7104 (1982)
Pulsed nitrogen laser excitation has been used to examine and compare the reactivities of four enol ethers toward singlet oxygen (1Δg) in five solvents.The experimental values of ΔH (0 +/- 1.0 kcal mol-1), ΔS (-23 to -34 eu), and the overall reaction rate constants (104-108 L mol-1 s-1) are characteristic of excited-state processes involving rapid reversible exciplex formation.Solvent effects are small but in some cases significant.It is concluded that such effects are the result of solvation entropy requirements at the transition state leading from exciplex to product, particularly in the case of dioxetane formation.The possibility is raised that the reversible exciplex mechanism operates generally for O2 (1Δg) reactions.
Living and Alternating Cationic Copolymerization of o-Phthalaldehyde and Various Bulky Enol Ethers: Elucidation of the "Limit" of Polymerizable Monomers
Hayashi, Keisuke,Kanazawa, Arihiro,Aoshima, Sadahito
, p. 1365 - 1375 (2022/02/23)
Cationic copolymerization of various bulky enol ethers, which have been difficult to homopolymerize and/or copolymerize, was shown to proceed when o-phthalaldehyde (OPA) was used as a comonomer. A series of enol ethers with various substituents on the β-carbon was synthesized from aliphatic aldehydes and alcohols. The relationships between the structures of the enol ethers and the copolymerization behavior were systematically investigated. As a result, monomers with one or two methyl and/or primary alkyl groups on the β-carbon were found to undergo alternating copolymerization with OPA. Moreover, living cationic copolymerization of enol ethers and OPA yielded alternating copolymers under appropriate polymerization conditions. To elucidate the limit of polymerizable monomers, the copolymerization of very bulky enol ethers such as β-t-butyl- or norbornenylidene-type monomers with OPA was also examined. OPA was found to be copolymerizable even with such very bulky monomers, indicating that the unique reactivity of the OPA-derived propagating carbocation with small steric hindrance is the key factor for successful copolymerization.
Stereoselective synthesis of β-C-D-glucopyranosides using the reaction of TMSCN and Grignard reagents with cyclic five-membered sulfonium salt intermediates
Liu, Hui,Smoliakova, Irina P
, p. 2973 - 2980 (2007/10/03)
In the presence of a Lewis acid, ArSCl adducts of tri-O-benzyl-D-glucal react with vinyl ethers to form cyclic five-membered sulfonium salt intermediates. The latter are capable of reacting with TMSCN and Grignard reagents furnishing exclusively 2-S-(aryl)-2-thio-β-C-D-glucopyranosides. The one-pot reaction also proceeds with high stereoselectivity of C-C bond formation in the lateral chain providing exclusively or predominantly C-glycosides with (S)-configuration of the chiral center in the lateral chain.
12-hetero substituted 6,11-ethano-6,11-dihydrobenzo (b) quinolizinium salts and compositions and method of use thereof
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, (2008/06/13)
1-Hetero substituted 6,11-ethano-6,11-dihydrobenzo[b]quinolizinium salts, pharmaceutical compositions containing them, and methods for the treatment or prevention of neurodegenerative disorders or neurotoxic injuries utilizing them.
The reaction of 1-chloro-2-methyl-2-propenyllithium with a selection of organolithiums. The development and synthetic utility of novel base/nucleophile combinations
Nelson, Donna J.,Nagarajan, Ananthanarayanan
, p. 1 - 6 (2007/10/02)
The title compound was generated by and reacted with (1) a series of reagents which have basic as well as nucleophilic properties and (2) a series of base/nucleophile combinations.Product yields of the isobutenyl derivative were generally low to very good, and the best results (89percent) were obtained by using a 1:2 ratio (3 equiv total) of nBuLi:LiPPh2.Synthetic utility of the reaction is optimized as it approaches a situation in which the base/nucleophile combination is composed of one compound which is both a strong base and a poor nucleophile and another compound which is both a weak base and a good nucleophile.
Nitrene-Transfer Reaction between Azide and Unsaturated Ether in the Presence of Pd(II) Catalyst
Migita, Toshihiko,Hongoh, Kazuya,Naka, Hiroyuki,Nakaido, Setsuko,Kosugi, Masanori
, p. 931 - 938 (2007/10/02)
Azidoformate reacted with allylic ethers to give 1-alkoxy-1-(alkoxycarbonylimino)alkane under catalysis by PdCl2(PhCN)2.The same imines were formed almost quantitatively by noncatalyzed reaction of the azide with the corresponding vinylic ethers.The rate
Une voie d'acces aux alcoxy-5 trimethyl-4,4,7a hexahydro-3aα,4,5,6,7,7aα (3H)-benzofurannones-2
Gosselin, Pascal,Rouessac, Francis,Zamarlik, Henri
, p. 192 - 198 (2007/10/02)
Starting from 2-methoxy (or ethoxy)-3,4-dihydro-2H-pyran, a series of four reactions allows to obtain a good yield of two 4-alcoxy-3,3-dimethyl-1-hydroxymethyl cyclohexenes which are converted to methylenecyclohexylacetic acids by different or sigmatropic reactions.These acids are cyclized at room temperature with concentrated sulfuric acid into bicyclic γ-lactones having a cis-junction.The stereospecificity of this reaction and the stability of the isomers obtained are discussed.
High-pressure kinetics of electron donor-acceptor complex formation and cycloaddition between tetracyanoethylene and enol ethers
Sasaki, Muneo,Tsuzuki, Hideaki,Osugi, Jiro
, p. 1596 - 1600 (2007/10/02)
The kinetics of the high-pressure cycloaddition reaction between tetracyanoethylene and enol ethers (n-butyl vinyl ether and ethyl 2-methylpropenyl ether) in chloroform have been studied, by following spectrophotometrically the disappearance of the electron donor-acceptor complex (e.d.a. complex) at 25°C and up to 1 500 bar. It is concluded that the e.d.a. complex is on the pathway to the zwitterionic intermediate and the final cycloaddition product. The reaction volume ΔV1 of e.d.a. complex formation is -11.0 ± 1.4 and -5.8 ± 1.0 cm3 mol-1 for n-butyl vinyl ether and ethyl 2-methylpropenyl ether, respectively. The volume of activation ΔV2? of cycloaddition step from e.d.a. complex to the adduct is -30.8 ± 1.5 and -41.8 ± 1.5 cm3 mol-1 for n-butyl vinyl ether and ethyl 2-methylpropenyl ether, respectively. The variation of ΔV 1 and ΔV2? is discussed from the viewpoint of the ionization potential and the electron density at the β-carbon atom of the enol ether.
