90769-69-0Relevant articles and documents
Unsaturated aldehydes as alkene equivalents in the Diels-Alder reaction
Taarning, Esben,Madsen, Robert
supporting information; experimental part, p. 5638 - 5644 (2009/05/30)
A one-pot procedure is described for using α,β-unsaturated aldehydes as olefin equivalents in the Diels-Alder reaction. The method combines the normal electron demand cycloaddition with aldehyde dienophiles and the rhodium-catalyzed decarbonylation of aldehydes to afford cyclohexenes with no electron-with-drawing substituents. In this way, the aldehyde group serves as a traceless control element to direct the cycloaddition reaction. The Diels-Alder reactions are performed in a diglyme solution in the presence of a catalytic amount of boron trifluoride etherate. Subsequent quenching of the Lewis acid, addition of 0.3% of [Rh(dppp)2Cl] and heating to reflux achieves the ensuing decarbonylation to afford the product cyclohexenes. Under these conditions, acrolein, crotonaldehyde and cinnamaldehyde have been reacted with a variety of 1,3-dienes to afford cyclohexenes in overall yields between 53 and 88%. In these transformations, the three aldehydes serve as equivalents of ethylene, propylene and styrene, respectively.
(ALKYLPHENYL)ALKYLCYCLOHEXANE AND METHOD FOR PRODUCING (ALKYLPHENYL)ALKYLCYCLOHEXANE OR ALKYLBIPHENYL
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Page/Page column 23-24, (2008/06/13)
Disclosed is a method for producing an (alkylphenyl)alkylcyclohexane comprising a step wherein an alkylbenzene and an alkylcyclohexene or alkylcyclohexanol are condensed in the presence of an acid catalyst. Also disclosed is an (alkylphenyl)alkylcyclohexane represented by the formula (8) below. An (alkylphenyl)alkylcyclohexane obtained by such a production method is converted into an alkylbiphenyl, a biphenylpolycarboxylic acid or a biphenylpolycarboxylic acid anhydride. This production method enables to easily and selectively obtain an (alkylphenyl)alkylcyclohexane and an alkylbiphenyl. (8) (In the formula, R1-4 represent an alkyl group having 1-4 carbon atoms, m represents an integer of 0-2, n' represents an integer of 2-5, and the other conditions are as defined in claim 18.)
Factors Influencing Conformational Preferences in Cyclohexenes
Lambert, Joseph B.,Marko, Dale E.
, p. 7978 - 7982 (2007/10/02)
Conformational preferences have been measured for the first time for 4-substituted cyclohexenes in a solvent of low polarity.Measurements were made for the substituents Cl, Br, I, OH, OSiMe3, and CN and were compared with conformational preferences in cyclohexyl and exo-methylenecyclohex-3-yl.In the nearly nonpolar solvent CF2Cl2, in which intramolecular interactions are maximized, there is a much larger axial population for cyclohexen-4-yl than in cyclohexyl or exo-methylenecyclohex-3-yl.In particular, the dipolar interaction of the endocyclic double bond is reduced from that of the exocyclic double bond.This observation is confirmed by the almost negligible effect of symmetrizing the endocyclic double bond through 1,2-dimethyl substitution, in contrast with the large effect of symmetrizing the exocyclic double bond through 7,7-dimethyl substitution.Polar solvents increase the proportion of the axial conformer to a smaller extent for the endocyclic than for the exocyclic system, again in agreement with a lower dipolar effect in the endocyclic case.These results emphasize the anisotropic nature of the steric effects of double bonds.