Fundamentals of ASymmeTric Organo-CATalysis

ended

For most biologically relevant molecules their chirality is decisive for their function. Within the last two decades asymmetric organo-catalysis has emerged as an environmental benign, metal-free alternative for conventional asymmetric transition metal catalysis. The organo-catalysts, which employ catalyst-substrate interaction motifs commonly found for enzymes, yield unprecedented enantiomeric excesses. Despite the success of these organo-chemical routes, remarkably little is known about the molecular details of the interaction between the catalyst and the substrate. Consequently, there is virtually no rationale method to optimize reaction conditions particularly as related to structure-function relationships. Also the exact nature of the intermediates that induce chirality has remained elusive. The aim of this proposal is to experimentally quantify the formation of reaction intermediates and the nature of intermediate induced chirality that lie at the heart of asymmetric control. This will be achieved by using a combination of advanced spectroscopic techniques. With advanced vibrational spectroscopies (ultrafast two-color and two-dimensional infrared spectroscopy), dielectric spectroscopy, and NMR spectroscopy together with quantum chemical calculations we will quantify structure-dependent interactions: binding geometry, strength of attraction, lifetime of binding, reaction intermediates, and the role of steric repulsion, probed on all timescales relevant to catalytic processes ranging from femtoseconds to seconds. Correlation of such information with the enantiomeric excess obtained in catalytic processes will allow isolating the essential ingredients for stereocontrol. Such molecular-level insights will provide fundamental parameters for optimization of reaction conditions and will initiate the transition from a trial and error approach towards a rational design of new catalytic processes.