Stereochemistry of thermal [1,5] carbon shifts in norcaradienes: complete kinetic analysis of the degenerate thermal isomerization of (+)-2-deuterio-3,7-dimethyl-7-(methoxymethyl)cycloheptatriene

Baldwin, John E.; Broline, Bruce M.

doi:10.1021/ja00374a027

Cited by 25 publications

(7 citation statements)

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“…After 6 min of reaction, the two peaks at 4.75 and 4.80 ppm corresponding to the 7,8 position have completely disappeared but the peak at 6.75 is still there, allowing one to conclude to the formation of only one epoxide isomer. The same situation has also been observed when meta -chloroperbenzoic acid had been used as the oxidizing agent . The results obtained for the epoxidation of carvone by in-situ-generated DMDO suggest that DMDO has an oxidizing capacity comparable to m -CPBA but in a greener way, being unable to epoxidize low electron density double bonds.…”

Section: Epoxidation Of α-Pinene and Other Terpenessupporting

confidence: 61%

“…The same situation has also been observed when meta-chloroperbenzoic acid had been used as the oxidizing agent. 60 The results obtained for the epoxidation of carvone by in-situ-generated DMDO suggest that DMDO has an oxidizing capacity comparable to m-CPBA but in a greener way, being unable to epoxidize low electron density double bonds.…”

Section: Scheme 2 Limonene Epoxidation Processmentioning

confidence: 94%

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Ultrasonic and Catalyst-Free Epoxidation of Limonene and Other Terpenes Using Dimethyl Dioxirane in Semibatch Conditions

Charbonneau

Foster

Kaliaguine

2018

ACS Sustainable Chem. Eng.

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Limonene dioxide is a key intermediate molecule for the development of biobased polycarbonates or nonisocyanate polyurethanes. In this work the epoxidation of limonene to limonene dioxide using in-situ-generated dimethyl dioxirane as the oxidizing agent under both conventional agitation and ultrasound has been compared. The time required to completely convert limonene to limonene dioxide with 100% yield using ultrasound was only 4.5 min at room temperature. In comparison, when conventional agitation using a magnetic stirrer is used, the required time to reach a 97% yield of limonene dioxide was 1.5 h. The epoxidation of α-pinene has also been studied using both agitation techniques. Epoxidation of α-pinene to α-pinene oxide under ultrasound required only 4 min with an obtained yield of 100%, while in comparison with the conventional method the reaction time was 60 min. As for other terpenes, β-pinene was converted to β-pinene oxide in only 4 min whereas farnesol yielded 100% of the triepoxide in 8 min. Carveol, a limonene derivative, was converted to carveol dioxide with a yield of 98%. In the epoxidation reaction of carvone using dimethyl dioxirane the conversion was 100% in 5 min, but only 7,8-carvone oxide was produced.

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Section: Epoxidation Of α-Pinene and Other Terpenessupporting

confidence: 61%

Section: Scheme 2 Limonene Epoxidation Processmentioning

confidence: 94%

Ultrasonic and Catalyst-Free Epoxidation of Limonene and Other Terpenes Using Dimethyl Dioxirane in Semibatch Conditions

Charbonneau

Foster

Kaliaguine

2018

ACS Sustainable Chem. Eng.

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“…Hydrogen Transfer Transition Structures. Thermal isomerizations of CHT and related compounds have been extensively discussed in the literature. − Houk and co-workers have summarized current progress in elucidation of hydrocarbon pericyclic reaction transition structures by computational means in an excellent review article . They point out that while many methods are able to estimate reasonable transition structure geometries, prediction of reaction barriers is considerably more problematic.…”

Section: Discussionmentioning

confidence: 99%

Molecular Orbital Studies of Methoxy-1,3,5-cycloheptatriene Isomers: Results from Semiempirical, ab Initio, and Density Functional Theory Calculations

Donovan

White

1996

J. Org. Chem.

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The fully optimized structures and relative energies of all possible methoxy-1,3,5-cycloheptatriene (MCHT) isomers have been determined by semiempirical, ab initio, and density functional theory (DFT) molecular orbital calculations. All methods identify the boat conformation of 1-methoxy-1,3,5-cycloheptatriene as the most stable species in this group of compounds. In order to evaluate boat interconversion barriers, optimizations of the planar isomers were also performed. For comparison purposes, we applied the same computational methodologies to boat and planar conformations of 1,3,5-cycloheptatriene (CHT). Among the semiempirical methods, the SAM1 approximation was found to best reproduce the ab initio and DFT results. Examination of rotational energy profiles allowed for identification of the factors controlling the preferred orientations of the methoxy group in these compounds. The calculations predict that methoxy substitution has little influence on the preferred conformation of the seven-membered ring and only a minor impact on the energy required for interconversion of boat conformations through a planar transition structure. Inclusion of electron correlation makes little difference on the calculated relative energies of the MCHT isomers and optimized geometries but significantly improves the computed reaction barriers involved in the CHT hydrogen transfer transition structures.

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“…(R)-and (S)-carvone (R-1 and S-1, respectively), sobrerol (2) and carvacrol (11) were purchased from Sigma-Aldrich Sweden AB (Stockholm, Sweden). The carvone epoxide 3 was prepared according to the procedure described by Baldwin and Broline (1982). 8-hydroxy-p-menth-6-en-2-one (4) was prepared according to the procedure described by Büchi and Wüest (1979).…”

Section: Compoundsmentioning

confidence: 99%

Carvone and less volatile analogues as repellent and deterrent antifeedants against the pine weevil, Hylobius abietis

Schlyter

Smitt

Sjödin

et al. 2004

J Applied Entomology

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The monoterpenoid carvone (1) has been shown to have strong antifeedant effects on Hylobius spp. However, because of the high volatility of carvone, long-time protection of conifer seedlings in the field using this compound has not been possible. We demonstrate, in several bioassay steps, that less-volatile, heavier analogues retain their preingestive feeding inhibition activity in the large pine weevil, Hylobius abietis (L.) for a longer time. The first step in the evaluation of the biological activity of 12 carvone analogues was a micro-assay, a choice test lasting 4 h. Compounds active at 100 nmol/cm 2 were further dose-response tested to give the effective dose needed to inhibit feeding by 50% (ED50). Of the 14 compounds tested, including both carvone enantiomers, seven heavier analogues were active at low doses (had low ED50 values). As expected from their lower vapour pressure compared with carvone, the heavier analogues proved more resistant to evaporation before testing. Thus, whereas the effect of 8-hydroxy-p-menth-en-6-one 4 declined after 2 days, some of the compounds with high molar masses, such as the alkylhydroxymenthenones 6 and 8, retained a stable activity for 4 days. The retained activity at 4 days was strongly correlated to molecular mass and boiling point. When tested on natural material (host Pinus sylvestris L. twig sections for 48 h), the heavier analogues showed a rather low activity. Probably, the activity of the more volatile compound carvone (1) is due to a repellent effect (olfactory mode) rather than the deterrent effects (gustatory mode) of the heavier compounds. In agreement with the relatively low activity on twigs in the laboratory, the hydroxymenthenone 4 was not active in the field when tested for 2 months as a 1 : 9 mixture with a polar wax.

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Stereochemistry of thermal [1,5] carbon shifts in norcaradienes: complete kinetic analysis of the degenerate thermal isomerization of (+)-2-deuterio-3,7-dimethyl-7-(methoxymethyl)cycloheptatriene

Cited by 25 publications

References 0 publications

Ultrasonic and Catalyst-Free Epoxidation of Limonene and Other Terpenes Using Dimethyl Dioxirane in Semibatch Conditions

Ultrasonic and Catalyst-Free Epoxidation of Limonene and Other Terpenes Using Dimethyl Dioxirane in Semibatch Conditions

Molecular Orbital Studies of Methoxy-1,3,5-cycloheptatriene Isomers: Results from Semiempirical, ab Initio, and Density Functional Theory Calculations

Carvone and less volatile analogues as repellent and deterrent antifeedants against the pine weevil, Hylobius abietis

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