Web Release Date: February 23,
Metallocene-Appended Imidazoles Displaying Virtual Planar Chirality
Department of Chemistry, Cardiff University, PO Box 912, Cardiff, CF10 3TB, U.K.
Received November 13, 2000
Abstract:
(S)-1-(1-Alkylethyl)imidazoles 6a/b (alkyl =
cyclohexyl, tert-butyl) containing a 2-(
5-cyclopentadienyl)(4-tetraphenylcyclobutadiene)cobalt substituent are
readily synthesized. The effect of the bulky metallocene
is to place the imidazoles in an environment of virtual
planar chirality as revealed by X-ray crystallography (of
6a), NOE difference NMR spectroscopy, and also their
highly diastereoselective reactions with Pd(OAc)2 resulting in new palladacycles 7a/b with (S)-(pR) configurations. The ability of the imidazole complexes to act as
nucleophilic catalysts was investigated, weak activity
being found for the promotion of the reaction between
ethanol and dimethylchlorophosphate.
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