Asymmetric amplification is a curious phenomenon which is believed to play a key role in the emergence of biological homochirality, and thus of life itself. In asymmetric catalysis, it is achieved via positive non-linear effects, which allow high product enantiomeric excesses with a non-enantiopure catalyst. However, it has also been proposed that non-enantiopure catalysts may be even more enantioselective than their enantiopure counterparts, though such a case has never been experimentally observed to date. Here we show an example of such a hyperpositive non-linear effect in asymmetric catalysis. We found that addition of dialkylzinc reagents to benzaldehyde gave higher product e.e.s with only partially resolved chiral N-benzyl-ephedrine ligands. A mechanistic study was carried out and our results point toward a two-component catalysis, where mononuclear as well as aggregated catalysts are in equilibrium and in competition. These results introduce an unprecedented class of asymmetric amplification in enantioselective catalysis.

The chiral ligand N-methylephedrine (NME) was found to catalyse the addition of dimethylzinc to benzaldehyde in an enantiodivergent way, with a monomeric and a homochiral dimeric complex both catalysing the...

Asymmetric amplification is a phenomenon that is believed to play a key role in the emergence of homochirality in life. In asymmetric catalysis, theoretical and experimental models have been investigated to provide an understanding of how chiral amplification is possible, in particular based on non‐linear effects. Interestingly, it has been proposed a quarter century ago that chiral catalysts, when not enantiopure might even be more enantioselective than their enantiopure counterparts. We show here that such hyperpositive non‐linear effect in asymmetric catalysis is indeed possible. An in‐depth study into the underlying mechanism was carried out, and the scheme we derive differs from the previous proposed models.