Preparation, reactivity, and structural studies of zincated C-nucleophiles.

摘要

Chapter 1. Zinc enolate complexes have been studied since the middle of the nineteenth century. Although a great deal is known about their reactivity, very little structural information has been catalogued. Information about the solid and solution state structures of five different zinc enolate complexes is presented and discussed. The reactivity of zinc enolates in additions to activated and unactivated alkenes, carbonyl moieties, and in transmetallation reactions is also discussed.; Chapter 2. Preparation of several zinc metallated amides and ketones from their respective bromides and activated zinc metal are reported. The amide solid state structures display a dimeric structure with two zinc centers bridging two amide molecules via C,O-metallation. The ketone complexes possess a Zn2O2 planar core with solely O-metallation. Pulsed field gradient DOSY NMR was employed to study the degree of aggregation of metallated diethylacetamide, bromo-acetic acid tert-butyl ester, and 2-bromo-2,4-dimethyl-3-pentanone. It was observed that in non-coordinating solvents (C6D6) higher degrees of aggregation were observed, on the order of tetramers. As the binding strength of the solvent was increased the degree of aggregation decreased to a dimer (THF-D8), and finally, a monomer (DMSO-D 6).; Chapter 3. Stoichiometric or catalytic quantities of simple 2° amines greatly increase the rate of H-Zn exchange between ZnPh 2 and a range of relatively non-acidic substrates, allowing for the convenient and direct preparation of alpha-functionalized organozincs for the first time without the use of strongly basic or halogenated reactants.; Chapter 4. Preparation of a new chiral, binucleating amino-alcohol ligand, LH2, derived from L-proline and its subsequent complexes with AlMe3 and AliBu3 are reported. LAl2iBu4, 1, displays approximate C2 symmetry with two four coordinate aluminum centers bound to the ligand through the chelating beta-aminoalcoholates and two isobutyl moieties. LAl4Me10, 2, rests on a crystallographic C2 axis of symmetry and has two four coordinate aluminum centers bound to the chelating beta-aminoalcoholates and two methyl groups, and two AlMe3 molecules datively bound to the ligand alcoholate. The interaction of 1 and 2 with various Lewis bases in solution was studied via 1H and variable temperature NMR.