14.9 (a) This diene has an s-cis conformation and should undergo Diels-Alder cycloaddition. (b) This diene has an s-trans conformation. Because the double bonds are in a fused ring system, it is not possible for them to rotate to an s-cis conformation. (c) Rotation can occur about the single bond of this s-trans diene. The resulting s-cis conformation, however, has an unfavorable steric interaction of a methyl group with a hydrogen at carbon 1. Rotation to the s-cis conformation is possible but not favored.

14.9 (a) This diene has an s-cis conformation and should undergo Diels-Alder cycloaddition. (b) This diene has an s-trans conformation. Because the double bonds are in a fused ring system, it is not possible for them to rotate to an s-cis conformation. (c) Rotation can occur about the single bond of this s-trans diene. The resulting s-cis conformation, however, has an unfavorable steric interaction of a methyl group with a hydrogen at carbon 1. Rotation to the s-cis conformation is possible but not favored.

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter16: Chemistry Of Benzene: Electrophilic Aromatic Substitution

Section16.SE: Something Extra

Problem 25VC: The following molecular model of a dimethyl-substituted biphenyl represents the lowest-energy...

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