Recent research inspired from nature drove the design of fully structured architectures. A significant number of building blocks have been developed to lead to systems with a high folding propensity, called foldamers. With their strong H-bonds network and their folding contributing to the pre-organization of the system, foldamers furnish relevant systems to mimic biopolymers structures. The design of new organocatalysts is a concern of main interest due to their non-toxicity, their ease to handle and they allow metal-free procedures. However most of organocatalysts from literature need high-loading (5-20 mol%) to allow good efficiency which is their main inconvenient. The very well defined 3D architectures of foldamers contribute to enhance catalysis efficiency with cooperative ligand binding, greater stabilization of charged intermediates and minimization of entropic cost of transition state (TS) binding. Towards the goal of developing foldamer-based organocatalysts, we have explored the use of isolated helical secondary structures in model stereo-controlled synthetic transformations. Our work focused on chiral aliphatic oligoureas, a class of helical foldamers bearing structural resemblance to the α-helical peptide backbone.<br/>Furthermore, the finding that anion binding occurs without helix unfolding suggested to us that oligourea foldamers could be useful in hydrogen bond and anion-binding catalysis. Here, we will show how conformational control can be used to rationally influence the reaction and improve catalytic efficiency. Details about the structure-activity relationships and substrate scope as a means to better understand the general principles governing oligourea foldamer-based catalysis will be discussed.

Oligourea foldamer-based asymmetric catalysis

254th National Meeting (2017)

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