Building bridges between Homogeneous and Heterogeneous Catalysis

List Group publishes their findings with “Science” Magazine

The scientists in Prof. Benjamin List's team normally work on homogeneous catalysis. However, the researchers have now noticed something unusual during their experiments.

Asymmetric cycloadditions are important for chemists as they help create complex ring-shaped molecules from simple reactants efficiently and with precise control over the arrangement of atoms. Harnessing asymmetric [6+4] cycloadditions to gain 10-membered-rings have been very challenging yet interesting. Researchers of the group of Prof. Benjamin List, Max-Planck-Institut für Kohlenforschung, have now found an unusual way to synthesize those enantioenriched compounds successfully. The group has published their findings in “Science”: A solid noncovalent organic double-helix framework catalyzes asymmetric [6 + 4] cycloaddition

“We tried to use our IDPi catalysts, but our first tries were not successful”, explains Dr. Tianyu Zheng, first author of the Science paper. The List group usually works on homogeneous reactions; all the compounds are – normally – in solution. But then, through serendipity, the scientists made an extraordinary observation: If the mixture within the test tube is not completely in solution but partly solid, things look quite differently. A homogeneous reaction becomes heterogeneous.

“We found that the tropone we were using forms solids”, says Tianyu Zheng. And together with the IDPi catalyst, a very strong confined chiral acid, the tropone had the desired effect and enantioenriched 10-membered rings were synthesized.

Having parts of the catalyst solid makes things even more easy for the chemists, as the catalyst may easily be regenerated and filtered after the reaction has finished – and then be reused.

“This method might also work for other components, not only Tropones”, says Tianyu. He is convinced that it is definitely worth trying, and thus building bridges between homogeneous and heterogeneous catalysis again.