- Non-heme iron catalysis in CC, C-H, and CH2 oxidation reactions. Oxidative transformations on terpenoids catalyzed by Fe(bpmen)(OTf)2
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The oxidation of terpene olefins with hydrogen peroxide in the presence of the non-hemo catalyst 5a afforded mixtures of epoxides whose composition was dependent upon the oxidation protocol used in each case. With terpenoid enones, the mixtures obtained evolved from clean epoxidation of α-ionone 23 to the clean allylic oxidation of damascone 28 due to the progressive deactivation of the electron density on the double bonds present in this series. The oxidation of bicyclic and tricyclic terpenoids afforded oxidation products coming from epoxidation, to olefin degradation, methyne and methylene activation products. Probably, the most attractive result was the synthesis of the Magnus lactone 46, from the tricyclic ether 45, with 88% yield and 100% conversion.
- Clemente-Tejeda, David,López-Moreno, Alejandro,Bermejo, Francisco A.
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p. 2977 - 2986
(2013/03/29)
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- NEW POLYOXYGENATED STEROID GLYCOSIDES FROM THE DEFENCE GLANDS OF SEVERAL SPECIES OF CHRYSOLININA BEETLES (COLEOPTERA: CHRYSOMELIDAE)
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The composition of the defence secretions of four species of Chrysolina beetles on feeding on St John's wort (Hypericum perforatum) has been investigated.In contrast with other members of this genus which produce cardiac glycosides these four species contain new polyoxygenated steroid glycosides.The structures of seven of these derivatives (3-9) have been determinated.
- Randoux, T.,Braekman, J. C.,Daloze, D.,Pasteels, J. M.,Riccio, R.
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p. 3879 - 3888
(2007/10/02)
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- 4-(1-HYDROPEROXY-1-METHYLETHYL)-1,3-CYCLOPENTADIENYL METHYL KETONE: ITS FORMATION FROM α-TERPINEOL AND BEHAVIOR AS A DIMETHYLFULVENE EPOXIDE.
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Ozonolysis of α-terpineol (1) then steam distillation in presence of acid gives the known 4-isopropylidenecyclopentenyl methyl ketone (4).This is oxidized in air to 4-(1-hydroperoxy-1-methylethyl)-1,3-cyclopentadienyl methyl ketone (10), a compound frequently reacting as if it were one of the elusive dimethylfulvene epoxides.It is converted by silica gel to two dimers (12, 13) of 2-acetyl-6,6-dimethylfulvene epoxide (19).Catalytic reduction of the dimers occurs mostly by exo addition of hydrogen to the conjugated double bond, and thermolysis of the dimers yields 4-acetyl-6,6-dimethylcyclohexa-2,4-dienone (20).With triphenylphosphine the hydroperoxide (10) yields two dimers of 2-acetyl-6,6-dimethylfulvene (26).This is the first reported isolation of dimers of a fulvene.The hydroperoxide (10) adds diazomethane to give an unstable pyrazoline (28); this pyrazoline loses nitrogen to yield a single isomer o' 5-acetyl-3',3'-dimethylbicyclohex-3-ene-2-spiro-2'-oxirane (29).Catalytic hydrogenation of the latter involves ring opening of the epoxide.
- Thomas, Alan F.,Perret, Celia
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p. 3311 - 3322
(2007/10/02)
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- The Oxidation of 1,8-Cineole by Pseudomonas flava
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Growth experiments of Pseudomonas flava, with cineole and various metabolites of cineole as the sole carbon and energy sources, yielded results which require alterations to a scheme by which P. flava is proposed to utilize these compounds.The optical purity of the metabolites obtained from achiral cineole has been reinvestigated.
- Carman, Raymond M.,MacRae, Ian C.,Perkins, Michael V.
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p. 1739 - 1746
(2007/10/02)
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- Selectivity and Reactivity in Some Oxidations with Pentavalent and Hexavalent Chromium Reagents: A Short Synthesis of Norbisabolide
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Selective oxidative cyclization of the t-hydroxyolefin (5) with pyridinium chlorochromate leads to a simple synthesis of norbisabolide (4).On the other hand, α-terpineol (7) on treatment with chromium(V) reagent undergoes facile oxidative cleavage followed by cyclization to give homoterpenyl methyl ketone (8).
- Kuchibhotla, Uma,Chakraborty, T. K.,Chandrasekaran, S.
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p. 1216 - 1218
(2007/10/02)
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