Synthesis of nitrogen heterocycles by condensation of the conjugate base of open-chain reissert compound analogs with vinyltriphenylphosphonium bromide (schweizer's salt)

Reaction of the conjugate base of several open-chain Reissert compound analogs with vinyltriphenylphosphonium bromide is shown to afford a convenient route to substituted pyrroles. The condensation is a two-step process involving an initial reversible addition to form an unstabilized Wittig reagent followed by an intramolecular Wittig reaction upon the carbonyl group of the tertiary amide functionality with concomitant elimination of HCN. Several applications to the synthesis of 1,2,5-trisubstituted pyrroles are presented, together with attempts to expand this methodology to the synthesis of other heterocyclic systems.