Dinuclear and ansa-titanocenes for enantioselective catalyst-controlled radical reactions and further applications

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Radical reactions play a crucial role in polymerization reactions and, more recently, are becoming increasingly important in well-defined C-C bond forming reactions. Realizing catalytic enantioselective radical reactions, however, has remained problematic. Recently, we demonstrated that radical cyclizations of ketonitriles run in presence of a chiral ansa-titanocene catalyst proceed with exceptional enantioselectivity and, thus, with excellent catalyst control. Based on our mechanistic studies, we herein propose the development of chiral dinuclear titanocene catalysts for the realization of further intra- and intermolecular enantioselective radical reactions. This includes new strategies for the synthesis of chiral-bridged cyclopentadienyl (Cp) ligands. Our approach will further lead to rapid and stereoselective syntheses of chiral ansa-titanocenes and Cp-complexes of other metals, which we will evaluate in typical applications and novel reactions. This way, we will overcome several classical problems in metallocene synthesis and significantly broaden the application range of such catalysts.