Synthetic Entry to the 2-Azatricyclo[4.3.2.04,9]undecane Ring System via Tropone

A synthesis of the 2-azatricyclo[4.3.2.04,9]undecane ring system—a hitherto unreported bridged azatricyclic ring system—beginning from tricarbonyl(tropone)iron and allylamine was accomplished in three steps: (1) aza-Michael addition of allylamine to tricarbonyl(tropone)iron; (2) Boc-protection of the resulting secondary amine; and (3) oxidative demetallation leading to a spontaneous intramolecular Diels–Alder reaction. The effect of a variety of parameters on the intramolecular Diels–Alder reaction was investigated, including diene and dienophile substitution patterns and dienophile tether length.