Diastereoselective and Enantioselective Aldol Condensations with Bis-Cyclopentadienyl Zirconium Enolates

Citation

McGee, Lawrence Ray (1982) Diastereoselective and Enantioselective Aldol Condensations with Bis-Cyclopentadienyl Zirconium Enolates. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/e2qn-kh88. https://resolver.caltech.edu/CaltechTHESIS:10212019-154636979

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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