A 3-STEP SYNTHESIS OF AN ENANTIOMERICALLY PURE HALOSTACHINE ANALOG STARTING FROM ETA-6-(ORTHO-TOLUALDEHYDE)-CHROMIUM-TRICARBONYL

An optically pure (+)-S-Halostachine analogue 5a was synthesized in 57% total yield and in three steps from optically pure(-)-aR-[o-tolualdehyde]-chromium-tricarbonyl complex 2a. Various optically pure Halostachine analogues having an ortho-substituted aromatic ring and of both configurations (R and S) are thus available by this route. An X-ray structure of the intermediate complexed oxazoline 3bI allowed to confirm the model we proposed for the approach of a nucleophile on these arene complexes.