Michinori Oki | Akateeminen Kirjakauppa

Rotation about the Carbon-Carbon single bond is generally
regarded to be unrestricted. About 50 years ago, rotational
isomers were found to exhibit optical activity: substituted
biphenyl derivatives. However, the author has investigated
other classes of compounds that have stable rotational
isomers at room temperature. These compounds can serve as
models for studying very weak intermolecular interactions,
that are difficult to observe. Even diastereotopic groups
show different chemical reactivity.
From the contents: The "Free Rotation Concept" - Rotamer
Populations - Barriers to Rotation - Reactivity of
Rotational Isomers.