Dizinc organometallics based on pre-organized binucleating bis(amidoamine) ligands; synthesis, structure, and reactivity of zinc enolates.

摘要

Chapter 1. A new class of dibenzofuran-bridged bis(amidoamine) and bis(ethylenediamine) ligands and their dinuclear lithium, aluminum, and zinc complexes are described. Copper-catalyzed coupling of 4,6-diiododibenzofuran with the requisite ethylenediamines yielded MeLH2, iPrLH2, and EtLH2. The MeLH2 species was used to form the lithium and aluminum derivatives MeLLi2 and MeLAl 2Me4. Lastly, the dizinc derivative MeLH 2Zn2Cl4 was prepared from MeLH 2 and ZnCl2.; Chapter 2. Several dizinc organometallics that are supported by dianionic bis(amidoamine) ligands are prepared. The ligand iPrLH 2 is utilized to form the species iPrLZn2Et 2 and iPrLZn2Me2 which both feature three-coordinated zinc centers in the solid-state.; Chapter 3. New dizinc complexes prepared from preorganized binucleating bis(amidoamine) ligands are reported.; Chapter 4. New dizinc complexes from preorganized binucleating bis(amidoamine) ligands are reported. The previously described dizinc complex MeLZn2Ph2 coordinates trimethylphosphine oxide yielding diadduct MeLZn2Ph2(OPMe 3)2.; Chapter 5. New dizinc enolates from simple ketones supported by binucleating bis(amidoamine) ligands are reported. The dizincs MeLZn2Ph2 and iPrLZn2Ph 2 are reacted with 2,4-dimethyl-3-pentanone to form MeLZn 2(OC(=CMe2)iPr)2 and iPrLZn2(OC(=CMe2) iPr)2 from the protonalysis of the ketone.; Chapter 6. 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 of halogenated reactants.; Chapter 7. Bulky zinc bis(amido) Zn(TMP)2 promotes the alpha-zincation of weakly acidic amides and esters. The alpha-zincated species readily add to aromatic and aliphatic aldehydes in the presence of a wide range of base sensentive functional groups. (Abstract shortened by UMI.)