Observation of Hyperpositive Non-Linear Effect in Asymmetric Organozinc Alkylation in Presence of N-Pyrrolidinyl Norephedrine

Phenomena related to asymmetric amplification are considered to be key to understanding the emergence of homochirality in life. In asymmetric catalysis, theoretical and experimental models have been studied to understand such chiral amplification, in particular based on non-linear effects. Three decades after the theoretical demonstration that a chiral catalyst, when not enantiopure, could be more enantioselective than its enantiopure counterpart, we show here a new experimental example of nonlinear hyperpositive effect. We report here our investigations in the enantioselective zinc-catalyzed alkylation of benzaldehyde with N-pyrrolidinyl norephedrine as partially resolved chiral ligand, which shows a significant hyperpositive non-linear effect. A study of the underlying mechanism was conducted, which allows us to confirm a mechanism that implies a monomeric and a dimeric complex both catalyzing the reaction at a steady state and giving different enantioselectivities.

Automated summary

Phenomena related to asymmetric amplification are crucial for understanding the emergence of homochirality in life. This study focuses on asymmetric catalysis and investigates non-linear effects in chiral amplification. The authors provide experimental evidence of a new nonlinear hyperpositive effect in enantioselective zinc-catalyzed alkylation. Their research also reveals a mechanism involving both monomeric and dimeric complexes that contribute to different enantioselectivities.