Novel chiral carbenes based on camphoric acid for asymmetric catalysis

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The proposal deals with the development of new chiral carbenes, which are based on camphoric acid. Due to this cheap chiral precursor, the desired ligands can be prepared in a few steps on a large scale. The NCN unit is embedded in a rigid bicyclic system being part of a six and seven-membered ring. Hence, the corresponding carbenes possess a higher basicity than carbenes with imidazolium and imidazolinium moieties, which is desirable in many catalytic applications. In addition, the free rotation of substituents next to the C(10) methyl group of the camphor skeleton is limited due to steric hindrance, which provides an asymmetric differentiation in a catalytic reaction step. The application of camphoric acid provides an easy route to six-membered ring carbenes with chiral information in the backbone. The introduction of useful chiral information for asymmetric catalysis in the backbone of a six-membered ring carbene is normally difficult. The new carbenes will be investigated in catalysis with a range of metals focusing in the beginning on Pd(II) and Pd(IV) catalyzed reactions. In addition, the application of the new ligands in metatheses reactions will be explored. Furthermore, it has been already shown that these carbenes can be used as organocatalysts in a [2+2] cycloaddition and their application will be extended in related reactions.