Synthesis and Reactivity of a Novel Class of Long-Lived Ammonium Ylides: Derivatives of Benzo[<i>b</i>]pyrrolo[2,1-<i>f</i>][1.6]naphthyridine

Reaction of 10-cyanotetrahydrobenzo[<i>b</i>][1,6]naphthyridines (<b>1−6</b>) with activated alkynes affords stable benzo[<i>b</i>]pyrrolo[2,1-<i>f</i>][1,6]naphthyridine-4-ium ylides (<b>7−14</b>) in moderate yields. A proposed mechanism for their formation consists of a new tandem multistage process.