Diastereoselective Synthesis of Planar Chiral Cobalt Metallocene Based Oxazoline Platinacycles

Reaction of (η5-(S)-2-(4-methylethyl)oxazolinylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt with cis-bis(dimethylsulfoxide)dichloroplatinum gave a 4.7:1 ratio of diastereomeric platinacycles, and the S,Rp-configuration of the major isomer was determined by X-ray crystallography. The same reaction on the corresponding t-Bu-substituted oxazoline derivative proceeded with a 5.6:1 selectivity, with the S,Rp-configuration of the major isomer determined by circular dichroism. Dimethylsulfoxide- and triphenylphosphine-ligated complexes are inactive as catalysts for the allylic imidate rearrangement of a trichloroacetimidate.