Entropy-Controlled Asymmetric Catalysis

Significance

Sohtome, Nagasawa, and colleagues report an enantioselective Friedel-Crafts reaction of phenols and nitroolefins using their recently developed flexible guanidine/bisthiourea catalyst 3. Extensive catalyst development allowed the authors to achieve very good enantio- and chemoselectivity in the reaction, which is normally prone to cascade processes. Kinetic studies based on the Eyring equation revealed an unprecedented mode of enantiodifferentiation based solely on entropic control. This type of activation is equally efficient over a wide range of temperatures and the entropy term can be presumably tuned by changing the reaction conditions.