Iron(0) Promotes Aza Cyclization of an Elusive Ferrocenylketene

The synthesis of a ferrocenylvinylketene as a stable η4-[Fe(CO)3] complex has been successfully accomplished through the reaction of η2-[Fe(CO)4] complex under mild carbonylation conditions. The reactivity of this ferrocenylketene under nucleophilic and thermal conditions has been explored. The mechanism of the thermal formation of a ferrocenylquinolizine through the reaction of the η4-[Fe(CO)3] ferrocenylvinylketene complex has been studied computationally within the density functional theory framework. The computational data reveal that this transformation proceeds through olefin isomerization, migration, and cyclization steps. The role of the [Fe(CO)3] moiety in this process has been established.