Electric-Field-Assisted Anion-π Catalysis

This report focuses on the remote control of anion-pi catalysis by electric fields. We have synthesized and immobilized anion-pi catalysts to explore the addition reaction of malonic acid half thioesters, to enolate acceptors on conductive indium tin oxide surfaces. Exposed to increasing electric fields, anion-pi catalysts show an increase in activity and an inversion of selectivity. These changes originate from a more than 100-fold rate enhancement of the disfavored enolate addition reaction that coincides with an increase in selectivity of transition state recognition by up to -14.8 kJ mol(-1). The addition of nitrate with strong pi affinity nullified (IC50 = 2.2 mM) the responsiveness of anion-pi catalysts to electric fields. These results support that the polarization of the pi-acidic naphthalenediimide surface in anion-pi catalysts with electric fields increases the recognition of anionic intermediates and transition states, on this polarized pi surface, that is, the existence and relevance of electric-field-assisted anion-pi catalysis.