ACS Cent. Sci. , Article ASAP DOI: 10.1021/acscentsci.6b00097 Publication Date (Web): May 23, 2016 Yoann Cotelle † ‡ , Vincent Lebrun † § , Naomi Sakai † ‡ , Thomas R. Ward * † § , and Stefan Matile * † ‡ † National Centre of Competence in Research (NCCR) Molecular Systems Engineering , Basel, Switzerland ‡ Department of Organic Chemistry, University of Geneva , CH-1211 Geneva, Switzerland § Department of Chemistry, University of Basel , CH-4056 Basel, Switzerland http://pubs.acs.org/doi/pdf/10.1021/acscentsci.6b00097 Abstract In this report, we introduce artificial enzymes that operate with anion-π interactions, an interaction that is essentially new to nature. The possibility to stabilize anionic intermediates and transition states on an π-acidic surface has been recently demonstrated, using the addition of malonate half thioesters to enolate acceptors as a biologically relevant example. The best chiral anion-π catalysts oper...