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