Dual reaction pathways in an open-chain Cope rearrangement

Lutz, Raymond P.; Bernal, S.; Boggio, Roberto; Harris, R. O.; McNicholas, M. W.

doi:10.1021/ja00745a028

Cited by 22 publications

(8 citation statements)

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“…We had established earlier that 4 rearranges cleanly through a chair-like transition state, yielding exclusively trans.trons-1,6-diphenylhexa-1,5-diene (5) as the kineti-Ph cally controlled product. 5 The pseudoequatorial disposition of phenyl groups in the transition state derived from 4 allows electronic interaction with the phenyl groups with minimal complications by steric effects.…”

Section: Photochemical Reactions Of Triphenyltin Hydride Withmentioning

confidence: 92%

Kinetics of the Cope rearrangement of a 3,4-diphenylhexa-1,5-diene

Lutz¹,

BERG²

1980

J. Org. Chem.

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Section: Photochemical Reactions Of Triphenyltin Hydride Withmentioning

confidence: 92%

Kinetics of the Cope rearrangement of a 3,4-diphenylhexa-1,5-diene

Lutz¹,

BERG²

1980

J. Org. Chem.

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“…( 5) product of an imaginary frequency factor v and a zero point energy (ZPE) term.14 The maximum value of the zero point energy term is reflected in the equilibrium isotope effect (EIE) which has been calculated at 1.027 for CH3I and 1.035 for CH3C1 in the hypothetical equilibrium pro-cess14 shown in eq 6. Values of the kinetic isotope effect CH3X ^CH3.…”

Section: Discussionmentioning

confidence: 99%

“…We had established earlier that 4 rearranges cleanly through a chair-like transition state, yielding exclusively trans.trons-1,6-diphenylhexa-1,5-diene (5) as the kineti-Ph cally controlled product.5 The pseudoequatorial disposition of phenyl groups in the transition state derived from 4 allows electronic interaction with the phenyl groups with minimal complications by steric effects.…”

Section: Methodsmentioning

confidence: 98%

Polar effect in alkyl radical reactions. Carbon kinetic isotope effects in halogen atom transfer to tin(III) and chromium(II)

TAMBLYN¹,

Vogler²,

Kochi³

1980

J. Org. Chem.

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“…The reaction described below gave largely recovered starting material, although the procedure was successful in previous preparations on a smaller scale (12).…”

Section: Methodsmentioning

confidence: 99%

Alumina-catalyzed Cope rearrangement

Wang¹

2000

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The alumina-catalyzed Cope rearrangements of meso-and dl-3,4-diphenylhexa-1,5-diene were examined in detail, follo~ing up a preliminary observation by H. Berg at Portland State University. Commercial column-chromatography grade alumina was·~mployed, and was further activated·before use.by heating at 650-700° for four hours.Using a ratio of 20 mg of dl-3,4~diphenylhex~-l,5-diene to 1 g of alumina in heptane, the Cope rearrangement was complete within 15 minutes at room temperature to give exclusively trans,trans-1,6-diphenylhexa-1,5-diene. This was identified.by melting point, infrared spectroscopy and vapor phase chromatography.The catalyzed rearrangement of meso-3,4-diphenylhexa-l,5-diene was run using the same diene to alumina ratio. It was found that.31% of the meso-diene was converted to cis,trans-and trans,trans-l,6-diphenylhexa-1,5-diene at room temperature in four hours. Product iso~ merization appeared to take place; the initial ratio of cis,trans-diene to trans,trans-diene was estimated to be 73:27. Another run was carried out at 60°, where the problem of isomerization of cis,trans-diene to trans,trans-diene was more pronounced. The rearrangement gave cis, trans-diene and trans,trans-diene in a ratio of 58:42, as estimated. by· extrapolation of the product ratio to zero time. Approximately 95% of meso-diene had reacted in one hour at this temperature. The extent of conversion of mes~-diene was calculated by quantitative infrared spectroscopy, and the isomeric distribution of products was determined by vapor phase chromatography.The product distribution in the alumina-catalyzed rearrangements parallels that of the thermal Cope rearrangement, where dl-die~e gives exclusively trans,trans-diene at 80° with a half-life of eight hours and ~-diene gives 63% cis,trans-diene and 27% trans,trans~diene at 120° with a half-life of 15 hours.

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Dual reaction pathways in an open-chain Cope rearrangement

Cited by 22 publications

References 0 publications

Kinetics of the Cope rearrangement of a 3,4-diphenylhexa-1,5-diene

Kinetics of the Cope rearrangement of a 3,4-diphenylhexa-1,5-diene

Polar effect in alkyl radical reactions. Carbon kinetic isotope effects in halogen atom transfer to tin(III) and chromium(II)

Alumina-catalyzed Cope rearrangement

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