If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



Same catalyst, different times, give different enantiomers

Reaction forms chiral amines in high selectivity

by Leigh Krietsch Boerner
July 6, 2020 | A version of this story appeared in Volume 98, Issue 26


Reacting the same starting materials gives both R and S products after different times.

Different molecular enantiomers can have different chemistry, both in the body and in industrial processes. Controlling the yield of the right one is a time-consuming yet critical step in organic and pharmaceutical synthesis. Shu-Li You and coworkers at the Shanghai Institute of Organic Chemistry have found a surprising and simple shortcut: they can selectively make either enantiomer of some chiral amines just by varying the reaction times (Nat. Chem. 2020, DOI: 10.1038/s41557-020-0489-1). They used an iridium cyclooctadiene compound and a chiral olefin to create a chiral catalyst in solution, a common approach for asymmetric synthesis. After 6 min, S isomers form with 84–99% enantiomeric purity. If the researchers let the reaction go for 10 h, the R isomer forms with 74–99% enantiomeric purity (shown). The catalyst is highly selective for the S isomer and makes the compound quickly, You says. Over time, however, it decomposes and the more stable R isomer forms. The team discovered this while monitoring the reaction every 10 min. You says he was shocked by the results, as no one has reported this effect in asymmetric catalysis before. The team is now studying if the effect occurs with other reactions.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.