Synthesis and reactivity of a novel class of long-lived ammonium ylides: derivatives of benzo[b]pyrrolo[2,1-f][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.