Studies on Intramolecular Coupling of Tricarbonyl(diene)iron Systems with Pendant Olefinic Groups: Configurational Requirements for Reactions of Acyclic Diene Complexes and Mechanistic Implications

Abstract

A photothermal cyclization reaction, which involves intramolecular coupling between a diene−Fe(CO)3 complex and a pendant olefinic group, has been studied for a number of acyclic diene complexes in which the olefinic group is attached as an ester, amide, keto, or alcohol derivative. While the cyclization will occur for complexes in which a methyl group is in the E stereochemical arrangement about the diene terminus, the transfer of hydrogen from this methyl to the metal, followed by reductive elimination to give a final cyclized material, does not occur. The latter process is shown to require a methyl group at the diene terminus in a Z configuration.