- A new solid-phase reaction system utilizing a temperature-responsive catalyst: Oxidative cyclization with hydrogen peroxide
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A switchable catalyst based on temperature change provides a novel solid-phase reaction system in water. An increase in catalyst affinity for organic substrates at higher temperature led to efficient activity driving the solid inner-phase reaction, and loss of affinity at lower temperature allowed easy separation of organic products upon completion of the reaction. Application of this catalyst intelligence to design a novel catalytic system brought about an efficient oxidative cyclization with hydrogen peroxide, a useful method of accessing oxygen heterocycles.
- Hamamoto, Hiromi,Suzuki, Yachiyo,Takahashi, Hideyo,Ikegami, Shiro
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p. 2685 - 2689
(2008/09/20)
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- Amides containing two norbornene fragments. Synthesis and chemical transformations
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Reactions of stereochemically pure bicyclo[2.2.1]hept-5-en-exo- and endo-2-ylmethylamines with bicyclo[2.2.1]hept-2-ene-5-carbonyl chlorides gave the corresponding carboxamides having two norbornene fragments. Their conformations and steric strains were studied by the MM2 molecular mechanics method, and electron density distribution in their molecules was determined by PM3 quantum-chemical calculations. The results of calculation of the energy of activation for epoxidation of the dienes in the gas phase and in solution (COSMO) showed that chemoselective oxidation of only one double bond therein is impossible. The corresponding diepoxy derivatives were synthesized by oxidation of the dienes with peroxyacetic acid; the oxidation of amides with endo orientation of the carbonyl group was accompanied by heterocyclization with formation of exo-2-hydroxy-4-oxatricyclo[4.2.1.03,7]nonan-5-one. Reduction of the amides and their epoxy derivatives with lithium tetrahydridoaluminate afforded the corresponding secondary amines possessing two cage-like fragments; the reduction products were functionalized at the nitrogen atom by treatment with p-nitrobenzenesulfonyl chloride and p-toluenesulfonyl isocyanate. The structure of the prepared compounds was confirmed by the IR and 1H and 13C NMR spectra.
- Kas'yan,Isaev,Kas'yan,Golodaeva,Karpenko,Tarabara
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p. 1415 - 1426
(2007/10/03)
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- Application of chemical P-450 model systems to studies on drug metabolism. Part X. Novel hydroxylactonization of γ,δ- and β,γ-unsaturated carboxylic acids with an iron porphyrin-iodosylbenzene system
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The oxidative hydroxylactonization of γ,δ- and β,γ-unsaturated carboxylic acids by a chemical cytochrome P-450 model and rat liver microsomal systems has been investigated. In the chemical system using meso-tetrakis(2,6-dichlorophenyl)porphyrin iron chloride [Fe(TDClPP)Cl] with iodosylbenzene (PhIO), γ,δ-unsaturated carboxylic acids have been converted into δ-hydroxy-γ-lactones in high yield and with high stereoselectivity. As an example of a β,γ-unsaturated carboxylic acid, indomethacin has been converted into the corresponding β-hydroxy γ-lactone. Several experiments directed toward mechanistic elucidation of the lactonization exclude a mechanism occurring via an epoxide intermediate. The products have been used as standards to identify the metabolites in the microsomal oxidation. In the case of indomethacin, the γ-lactone form is detected as a metabolite in the rat liver microsomal system, in a yield of 1.33%; the yield is significantly decreased in the presence of 2-diethylaminoethyl-2,2-diphenylvalerate hydrochloride (SKF-525A) and under a mixed CO-O2 (4:1) atmosphere. Thus, these metabolites are considered to be formed by a cytochrome P-450-dependent reaction.
- Komuro, Masakatsu,Higuchi, Tsunehiko,Hirobe, Masaaki
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p. 2309 - 2313
(2007/10/03)
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- A Further Synthetic Approach to the Adamantane Isomer 2,5-Trimethylenenorbornane (Tricyclo3,9>decane, 4-Homotwistbrendane)
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A further synthetic approach to 2,5-trimethylenenorbornane (1; tricyclo3,9>decane, 4-homotwistbrendane), a member of the "adamantaneland", is described starting from methyl 5-oxo-2endo-norbornanecarboxylate (5).The required C2-chain was introduced by a Wittig-Horner reaction and the ring closure of the trimethylene bridge achieved by an acyloin condensation.
- Kaenel, Hans-Ruedi,Ganter, Camille
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p. 2453 - 2457
(2007/10/02)
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- ACTION DU N-BROMOSUCCINIMIDE SUR LES DIOXOLANNES EN SERIE BICYCLOHEPTANIQUE. LIMITATION DES TRANSPOSITIONS DE WAGNER-MEERWEIN
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Vicinal benzoyloxy-trans-bicycloheptanic bromhydrins, otherwise difficult to obtain are formed from N-bromosuccinimide and norbornanes bearing a 2-aryl-1,3 dioxolane skeleton.The greater stability of the intermediate dioxolenium ion reduces the tendency towards both Wagner-Meerwein rearrangement and neighbouring group participation by chlorine, processes usually observed when a less stable intermediate is involved.Nevertheless, methoxycarbonyl neighbouring group participation and Wagner-Meerwein rearrangement occur in methoxycarbonylbicycloheptane and in a bornanic compound respectively.
- Bazbouz, Akram,Christol, Henri,Coste, Jacques,Plenat, Francoise
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p. 2745 - 2755
(2007/10/02)
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