Diastereoselective Oxidation of Lithium and Chlorotitanocene Enolates Derived from Camphor

Abstract

The diastereoselective oxidation of the camphor lithium enolate 2 and the corresponding chlorotitanocene enolate 4 by various electrophilic oxidants has been examined. The diastereoselectivity of the oxygen transfer depends on the metal fragment coordinated to the enolate. Thus, the chlorotitanocene enolate 4 leads to a much higher diastereomeric excess (de 88 to > 90%) than the corresponding lithium enolate 2 (de 12 to 60 %), with the formation of exo-3-hydroxycamphor (5) as the main isomer. Copyright © 1996 Elsevier Science Ltd.