Cross-Metathesis of an Iron Carbene with Diazenes

Abstract

Olefin metathesis is one of the most versatile reactions in synthetic chemistry. Metathesis of C═X (X = O, NR2) substrates has also been developed; however, the simple cross-metathesis of diazenes and olefins remains unrealized, in part due to the lack of mechanistic information about deactivation pathways for traditional olefin cross-metathesis catalysts. Herein, we report the reactions of [{PC(sp2)P}Fe(NCtBu)(N2)] ([PC(sp2)P] = bis(2-di-iso-propylphosphino)methylene) with cyclic diazenes and the formation of metathesis-related products. These reactions led to the isolation of a diazametallacyclobutane from diazocine that ring opens to afford an in situ iron imide complex, which undergoes an intramolecular C–H amination to afford an iron indoline. Restricting this side reaction with dibenzodiazepine led to the formation of an iron imide complex, which was structurally characterized in its oxidized form.