Electron-rich heptafulveneiron tricarbonyl complexes. synthesis and reactions of 8-alkoxyheptafulvene-Fe(CO)₃ derivatives

The synthesis of a series of stable 8-alkoxyheptafulvene-Fe(CO)₃ complexes V, VI and VIII from the appropriate acycloheptatriene-Fe(CO)₃ complexes is described. Tetracyanoethylene cycloadds to complexes V and VIII in a 8 + 2 manner, giving X and XI respectively. Oxidation of X with cerium(IV) gives the tetrahydroazulene complex XIV. Similarly, N-phenyltriazolinedione reacts with V affording the imidoacetal adduct XII, which is readily hydrolyzed to form the water soluble imidoaldehyde complex XIII. ¹³C NMR studies indicate that the exocyclic double bond has no significant polar character.