Cyclohexene methyl group influence

AhydH was measured in n-hexane solution. The sequence -28.5, -27, and -22.5 for Ahyd7/ of cyclohexene, cyclopentene, and 1,2-dimethylcyclopentene shows the influence of hydrogen atom crowding in the cyclopentane ring relative to cyclohexane (product destabilization) and reactant stabilization of the double bond in 1,2-dimethylcyclohexene by two a methyl groups. 

As far as the dioxolane ring-containing compounds are concerned, no conclusions about the influence of the substituents on the reaction rate can be drawn. Thus, the epoxidation rate constant k of the compounds X, VI and VII differs only a little from that of cyclohexene. The introduction of two methyl groups into the cyclohexene ring (VI) does not increase the reaction rate although the methyl group has electron-donor properties. 

The influence of the methyl group in cyclohexene and the methylene bridge in nor-bornene rings on bromination and its stereochemistry have been studied. The effect of base concentration, base type, reaction temperature, and solvent on bromination at the C(3) and C(5) positions of a 1,4-dihydropyridine was also investigated. ... 

Z)-2-Methoxy-l-(phenylthio)-l,3-butadienes react with methyl vinyl ketone and with 2-cyclohexen-1-one under catdysis by magnesium bromide or ethylaluminum dichloride. This provides exclusively the C 0 endo adducts in which the regiochemistry is completely controlled by the sulfur substituent despite the juxtaposed influence of the OMe group, e.g. (143) (144) (Scheme 36). ... 

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