Single and Consecutive Cyclization Reactions of Alkynyl Carbene Complexes and 8‐Azaheptafulvenes: Direct Access to Polycyclic Pyrrole and Indole Derivatives

The reactivity of alkynyl and enynyl Fischer carbene complexes towards 8‐azaheptafulvenes is examined. Alkynyl carbenes 1 a – f undergo regioselective [8+2] heterocyclization with 8‐aryl‐8‐azaheptafulvenes 2 a ,  b providing cycloheptapyrroles 3 and 4 with metal carbene or ester functionality at C3. Moreover, consecutive cyclization reactions are involved when enynyl carbenes are used. Thus, the cyclopenta[ b ]pyrrole framework 7 is formed by the consecutive [8+2] cyclization and cyclopentannulation reactions. The initially formed cyclopentannulation adduct can be intercepted through a Diels–Alder reaction with classic dienophiles to afford increasing structural complexity (compounds 8 and 9 ). More importantly, the construction of the indole skeleton is accomplished with a high degree of substitution and functionalization (compounds 11 – 15 ) by a one‐pot sequence that involves [8+2] cyclization, RNC or CO insertion, and ring closure.