Use of a Methoxy Substituent in Controlling the Stereochemistry of Intramolecular Iron-Mediated Diene/Olefin Cyclocoupling

A methodology for stereocontrol during the intramolecular coupling between cyclohexadiene--Fe(CO)(3) complexes and pendant alkenes is presented. Introduction of a methoxy group at the C(3) position of the diene moiety controls pre- and postcyclization rearrangements of the diene Fe(CO)(3) unit, allowing the preparation of spirolactams with defined relative stereochemistry and with a cyclohexenone framework, thus making this reaction a potentially valuable tool for the construction of quaternary carbon centers.