Alexander L. Reznichenko

The mechanism of hydroaminoalkylation catalyzed by group 5 metal binaphtholate complexes.

The intermolecular hydroaminoalkylation of unactivated alkenes and vinyl arenes with secondary amines occurs readily in the presence of tantalum and niobium binaphtholate catalysts with high regio- and enantioselectivity (up to 98% ee). Mechanistic studies have been conducted in order to determine the kinetic order of the reaction in all reagents and elucidate the rate- and stereodetermining steps. The effects of substrate steric and electronic properties on the overall reaction rate have been evaluated. The reaction is first order in amine and the catalyst, while exhibiting saturation in alkene at high alkene concentration. Unproductive reaction events including reversible amine binding and arene C-H activation have been observed. The formation of the metallaaziridine is a fast reversible nondissociative process and the overall reaction rate is limited either by amide exchange or alkene insertion, as supported by reaction kinetics, kinetic isotope effects, and isotopic labeling studies. These results suggest that the catalytic activity can be enhanced by employing a more electron-deficient ligand backbone.

Early Transition Metal (Group 3–5, Lanthanides and Actinides) and Main Group Metal (Group 1, 2, and 13) Catalyzed Hydroamination

The hydroamination of alkenes, dienes, allenes, and alkynes by early transition metal catalysts has seen significant progress over the last decade, especially with respect to control of regio- and stereoselectivity and the synthesis of more complex nitrogen-containing skeletons. This article provides an overview over the application of catalyst systems based on the 17 rare earth elements, as well as group 4 and group 5 metals. These electropositive metal catalysts operate via activation of the amine to form catalytic active metal-amido or metal-imido species, although the true nature of this species is not known with certainty for all systems and may vary for different substrate classes. This mode of activation differentiates early transition metal catalysts from many late transition metal catalysts that operate via activation of the unsaturated C–C linkage (alkene, 1,3-diene, allene, or alkyne). Alkali metals, alkaline earth metals and aluminum are included in this overview as well, as they show strong similarities in their reactivity and mechanistic pathways to aforementioned early transition metals. While the structure-reactivity principles are well understood for certain hydroamination processes, e.g., in the intramolecular hydroamination of aminoalkenes or the intermolecular hydroamination of alkynes, other transformations, in particular the intermolecular hydroamination of alkenes, remain highly challenging. Due to the potential of the hydroamination process for the synthesis of pharmaceuticals and other industrially relevant fine chemicals, a strong emphasis is given on the application of chiral catalysts in stereoselective processes.

Catalytic σ-Bond Metathesis

This account summarizes information on recently reported applications of organo-rare-earth metal complexes in various catalytic transformations of small molecules. The σ-bond metathesis at d0rare-earth metal centers plays a pivotal role in carbon–carbon and carbon–heteroatom bond forming processes. Relevant mechanistic details are discussed and the focus of the review lies in practical applications of organo-rare-earth metal complexes.

Stereoselective addition of simple amines to unactivated alkenes

of the Dissertation ............................................................................................... ii Acknowledgements ............................................................................................................ iv Table of