Tetra-Substituted Ethylenes

Ireland, C. J.; Jones, Kathleen; Pizey, J. S.; Johnson, Sherida

doi:10.1080/00397917608072629

Cited by 40 publications

(18 citation statements)

References 4 publications

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“…The diester 13 17 underwent the CA–RE reaction to form the single product 14 , as confirmed by X‐ray analysis (see Figure S5 in the Supporting Information, δ r value for the DMA ring = 0.042 Å), although reaction times at 23 °C were slower, requiring 22 h to reach completion. When the isomeric diester 15 18 was used, the three products 16 – 18 were obtained. Although four isomeric products can potentially form in the CA–RE reaction, only compounds 17 and 18 were observed with an E / Z configuration at the C4–C5 double bond.…”

Section: Resultsmentioning

confidence: 99%

Ester‐Substituted Electron‐Poor Alkenes for Cycloaddition–Retroelectrocyclization (CA–RE) and Related Reactions

et al. 2015

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We report the reactions of electron‐deficient alkenes, tetrasubstituted by carboxylic ester and cyano groups, with electron‐rich (dimethylamino)phenyl‐substituted alkynes. Mono‐ or diester‐substituted alkenes exclusively undergo the [2+2] cycloaddition–retroelectrocyclization (CA–RE) reaction, well established for multicyanated ethenes, whereas tri‐ and tetraester‐substituted alkenes also undergo a [4+2] hetero‐Diels–Alder (HDA) reaction with a third product being formed, presumably by a [3+2] cycloaddition reaction followed by rearrangement. Electrochemical studies revealed cathodic shifts of the first reduction potential of the buta‐1,3‐dienes obtained from the CA–RE reaction as cyano groups are substituted for ester moieties. Post‐CA–RE functionalization of the ester‐substituted buta‐1,3‐dienes by transesterification, diazonium chemistry, and cross‐coupling is described. The formation of a pharmacologically interesting pyrazolopyran illustrates the synthetic utility of ester‐substituted CA–RE products.

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Section: Resultsmentioning

confidence: 99%

Ester‐Substituted Electron‐Poor Alkenes for Cycloaddition–Retroelectrocyclization (CA–RE) and Related Reactions

et al. 2015

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“…Dimethyl dicyanofumarate was prepared by the method reported in the literature. 26 Synthesis of the pinacol donors. The pinacols substituted with methyl groups on the bridge were synthesized by reductive coupling of the corresponding acetophenones, promoted by samarium diiodide, as follows.…”

Section: Methodsmentioning

confidence: 99%

Direct Measurement of Ultrafast Carbon−Carbon Cleavage Rates via the Subpicosecond Charge-Transfer Activation of Pinacols

Bockman

Kochi

1998

J. Am. Chem. Soc.

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Highly transient (benzpinacol) cation radicals (D 2 +• ) and their ultrafast mesolytic fragmentations to the diarylhydroxymethyl radical (D • ) and cation (D + ) are directly observed on the early picosecond time scale upon the charge-transfer photoactivation of the intermolecular donor-acceptor complexes of pinacol donors with methyl viologen. Ultrashort lifetimes of the cation radicals with τ ≈ 10 ps obtain (for the first time) from quantitative kinetics analysis of the time-resolved spectroscopic results. These rapid C-C bond scissions successfully compete with back-electron transfer, which normally predominates on this time scale, and lead to exceptionally high efficiencies for the oxidative fragmentation of pinacols.

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“…The synthesis of bis(dicyanofumarate) was achieved by treating a solution of methylcyanoacetate and ethylene glycol dicyanoacetate in a 5:1 ratio in tetrahydrofuran with an excess of thionyl chloride, adapting a procedure described in the literature. [14] The bis(dicyanofumarate) was less soluble than the dimethyldicyanofumarate and precipitated at the end of the reaction. Thorough washing with a mixture of chloroform and ethyl acetate gave bis(dienophile) 2 free of dimethyl dicyanofumarate in approximately 46 % yield (Scheme 2).…”

Section: Synthesis Of the Materialsmentioning

confidence: 99%

Room Temperature Dynamic Polymers Based on Diels–Alder Chemistry

Reutenauer

Buhler

Boul

et al. 2009

Chemistry A European J

269

191

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Dynamers based on reversible Diels-Alder chemistry have been obtained and shown to undergo dynamic exchange at room temperature. Their study in solution by small-angle neutron scattering indicated the formation of long and highly flexible chains. Polydispersed molecules gave T(g) values below room temperature, permitting the generation of a dynamic elastomer upon introduction of a dynamic cross-linking agent. The use of a system with a low equilibrium constant gives access to materials with interesting self-healing properties.

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Tetra-Substituted Ethylenes

Cited by 40 publications

References 4 publications

Ester‐Substituted Electron‐Poor Alkenes for Cycloaddition–Retroelectrocyclization (CA–RE) and Related Reactions

Ester‐Substituted Electron‐Poor Alkenes for Cycloaddition–Retroelectrocyclization (CA–RE) and Related Reactions

Direct Measurement of Ultrafast Carbon−Carbon Cleavage Rates via the Subpicosecond Charge-Transfer Activation of Pinacols

Room Temperature Dynamic Polymers Based on Diels–Alder Chemistry

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