Hydroamination and C-H activation reactivity of tetrakis(amido), bis(amidate) and bis(2-pyridonate) complexes of titanium and zirconium

The work reported herein focuses on expanding the reaction scope of known group four bis(amidate) and tetrakis(amido) complexes in hydroamination catalysis. The development of new titanium and zirconium complexes exhibiting improved reactivity in hydroamination catalysis and unexpected C-C bond formation are disclosed. The exceptional hydroamination activity of a bis(amidate) titanium bis(amido) precatalyst towards alkynes in the presence of aryl amine co-substrates is elucidated, and the scope of this reactivity was found to include examples of room temperature intermolecular hydroamination. The application of commercially available tetrakis(dialkylamido) titanium(IV) as a precatalyst for the cyclohydroamination of aminoalkenes to form N heterocyclic products is a particularly attractive contribution due to the ready availability and ease of use associated with this catalyst system. The second section involves efforts to develop more reactive and selective bis(amidate) bis(amido) hydroamination precatalysts by the rational design and implementation of new amidate ligands modified for enhanced reactivity and selectivity including attempts at enantioselective catalysis. The synthesis and characterization of a bis(amidate) titanium bis(amido) complex incorporating electron withdrawing perfluorophenyl groups for enhanced reactivity, along with the assessment of this system in terms of hydroamination is presented. The synthesis, characterization and evaluation of chiral amidate ligands for the asymmetric cyclohydroamination of aminoalkenes is also described. In order to generate more reactive group four hydroamination precatalysts, 2- pyridone and its derivatives were investigated as a new class of amidate N,O chelating proligand. The synthesis and characterization of the first group four bis(2-pyridonate) bis(amido) complexes is presented along with their reactivity towards aminoalkenes. These novel complexes were found to be reactive for both cyclohydroamination and catalytic intramolecular a-functionalization. The initial findings along with a substrate scope analysis, and preliminary mechanistic investigations for this unique and exciting 100% atom economic, catalytic C-C bond forming reaction is included. The work described in this dissertation contributes to understanding of group four metal catalyzed reactions by illuminating some previously unknown reactivity associated with titanium and zirconium as well as by providing further insight into how ligand structure influences complex reactivity.Science, Faculty ofChemistry, Department ofGraduat

A Rhodium IBiox[(−)-menthyl] Complex as a Highly Selective Catalyst for the Asymmetric Hydroarylation of Azabicyles: An Alternative Route to Epibatidine

The synthesis and characterization of a new chiral rhodium N-heterocyclic carbene complex, Rh(IBiox[(−)-menthyl](CO)2Cl, is reported. In addition, the very high enantioselectivity exhibited by this complex, as a catalyst for the asymmetric hydroarylation of azabicycles, is demonstrated and applied to the synthesis of epibatidine

A Rhodium IBiox[(−)-menthyl] Complex as a Highly Selective Catalyst for the Asymmetric Hydroarylation of Azabicyles: An Alternative Route to Epibatidine

The synthesis and characterization of a new chiral rhodium N-heterocyclic carbene complex, Rh(IBiox[(−)-menthyl](CO)2Cl, is reported. In addition, the very high enantioselectivity exhibited by this complex, as a catalyst for the asymmetric hydroarylation of azabicycles, is demonstrated and applied to the synthesis of epibatidine

A Rhodium IBiox[(−)-menthyl] Complex as a Highly Selective Catalyst for the Asymmetric Hydroarylation of Azabicyles: An Alternative Route to Epibatidine

The synthesis and characterization of a new chiral rhodium N-heterocyclic carbene complex, Rh(IBiox[(−)-menthyl](CO)2Cl, is reported. In addition, the very high enantioselectivity exhibited by this complex, as a catalyst for the asymmetric hydroarylation of azabicycles, is demonstrated and applied to the synthesis of epibatidine

Enhanced Reactivity Results in Reduced Catalytic Performance: Unexpected Ligand Reactivity of a Bis(<i>N</i>-2,6-diisopropylphenylperflourophenyl-amidate)titanium-bis(diethylamido) Hydroamination Precatalyst

A bis(amidate)titanium-bis(amido) complex incorporating electron withdrawing pentafluorophenyl substituents has been prepared to enhance reactivity in this class of hydroamination precatalyst. This bis(N-2,6-diisopropylphenylperflourophenylamidate)titanium-bis(diethylamido) titanium complex has been fully characterized, including its X-ray crystal structure. As a precatalyst, the title compound proved to be effective for intermolecular hydroamination of internal and terminal alkynes with primary amines with yields as high as 97% and modest intramolecular alkene hydroamination. However, the elevated reactivity of this complex also resulted in reduced Markovnikov/anti-Markovnikov selectivity with some terminal alkynes. Substrate scope limitations revealed that this complex is susceptible to decomposition as a direct consequence of nucleophilic addition of the amine substrate to the pentafluorophenyl substituent of the amidate ligand

A Pentagonal Pyramidal Zirconium Imido Complex for Catalytic Hydroamination of Unactivated Alkenes

The first, isolable group 4 imido complexes capable of promoting intramolecular olefin hydroamination for the preparation of N-containing heterocycles are presented. The structurally characterized 6-coordinate bis(amidate)-supported zirconium imido complex is a rare example of distorted-pentagonal-pyramidal geometry

A Pentagonal Pyramidal Zirconium Imido Complex for Catalytic Hydroamination of Unactivated Alkenes

The first, isolable group 4 imido complexes capable of promoting intramolecular olefin hydroamination for the preparation of N-containing heterocycles are presented. The structurally characterized 6-coordinate bis(amidate)-supported zirconium imido complex is a rare example of distorted-pentagonal-pyramidal geometry