Biphenyl atropisomers are well-known scaffolds for chiral ligands used in enantioselective organometallic reactions, and the effect of ortho substituents on the torsional barrier along the biphenyl axis has been assessed on several occasions. Yet, would activation barriers be altered upon encapsulation of the biphenyl unit into a macrocyclic host? In this study, we show that CB[8] behaves as a molecular brake upon encapsulation of substituted biphenyl units flanked by a sulfonium group at their 3-position.

Atropisomerism in confined space: The impact of cucurbit[8]uril on the torsional barrier of biphenyl units

243rd National Meeting (2012)

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