Organometallics, 24 (1), 77 -81, 2005. 10.1021/om0493614 S0276-7333(04)09361-6
Web Release Date: November 30, 2004

Copyright © 2004 American Chemical Society

Synthesis of tert-Leucine-Derived Cobalt Oxazoline Palladacycles. Reversal of Palladation Diastereoselectivity and Application to the Asymmetric Rearrangement of N-Aryl Trifluoroacetimidates

R. Shyam Prasad, Carolyn E. Anderson, Christopher J. Richards,* and Larry E. Overman*

Department of Chemistry, Queen Mary, University of London, Mile End Road, E1 4NS, U.K., and Department of Chemistry, University of California, Irvine, 516 Rowland Hall, Irvine, California 92697-2025

Received August 17, 2004

Abstract:

Starting from (5-carboxycyclopentadienyl)(4-tetraphenylcyclobutadiene)cobalt, (5-(S)-2-(4-tert-butyl)oxazolinylcyclopentadienyl)(4-tetraphenylcyclobutadiene)cobalt and (5-(S)2-(4-methyl)oxazolinylcyclopentadienyl)(4-tetraphenylcyclobutadiene)cobalt were synthesized in 70 and 79% yield, respectively. On heating with palladium acetate, only the former oxazoline resulted in the formation of a palladacycle (79% yield) that was determined to have an (S)-(pS)-configuration. Following ligand exchange (acetate to chloride to trifluoroacetate), the tert-butyl palladacycle was applied as a catalyst for the rearrangement of N-(4-methoxyphenyl)trifluoroacetimidates.

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