Diastereoselective and Enantioselective Aldol Condensations with Bis-Cyclopentadienyl Zirconium Enolates

Author: McGee, Lawrence Ray

Year: 1982

Degree: Dissertation (Ph.D.)

Advisor: Evans, David A.

Committee Members: Evans, David A.; Gagne, Robert R.; Dougherty, Dennis A.; Collins, Terrence J.; Roberts, John D.

Option: Chemistry

DOI: 10.7907/e2qn-kh88

Abstract

Bis-cyclopentadienyl zirconium enolates undergo aldol condensation to afford erythro aldol adducts regardless of enolate configuration. Enolates of chiral amides afford high levels of asymmetric induction at the erythro stereo-centers. Mild hydrolysis of the chiral auxiliaries occurs via intramolecular assistance by hydroxyl neighboring groups in the chiral auxiliary. The absolute configurations of the erythro-aldol products have been determined by independent correlations to compounds of known absolute configuration. A cyclic metal-centered transition state model has been developed which accounts for the stereoselectivity observed with zirconium enolates.

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