LIGDES · Ligand Design for Asymmetric Cyclo-addition Reactions

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Project objective

Among the most widely used methods for the catalytic asymmetric formation of the carbon-carbon bond are Diels-Alder reactions. The hetero-Diels-Alder (HDA) reaction between 1,3-dienes and carbonyl compounds provides a perfect access to dihydropyranone and dihydropyran derivatives, a class of compounds extensively utilized in the total synthesis of sugars.The main target of this project is to construct highly selective and reactive chiral catalysts for HDA reactions. Experimentally observed but unexplained l igand-dependent catalytic properties of several chiral salen complexes for enantioselective [4+2] cyclo addition of buta-1,3-dienes to alkyl glyoxylates constitute an interesting case for proposed theoretical study.Due to the size of the system this calls f or the implementation of a QM/MM (DFT/Amber) computational strategy that can be correctly applied to determine the molecular mechanism of different variants of HDA cyclo addition reaction.These studies are expected to explain how the coordination of Lewis acids will affect transition-state conformations in the cyclo addition reactions. Next step will be to introduce some modifications to salen chiral ligands trying to deduce the role of these substituents in determining enantioselective discrimination. Of particular interest is how the steric and electronic factors will affect the reaction mechanism, as it will provide us with some information about the possible architecture of catalyst. Then, we shall analyse the physical nature of intermolecular interactions of catalyst's ligands with reactants using Differential Transition State Stabilisation approach.This opens a possibility to obtain, in a fully non-empirical way, contributions of particular ligand to the catalytic field. Our knowledge about the optimal molecular environment for each HDA reaction variant will serve as a base for the construction and screening of the best candidates for ligands in the cyclo addition reaction.

Original text from CORDIS.

Participants

• POLITECHNIKA WROCLAWSKA · WROCLAWCoordinatorPoland

Links

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