Synthesis of Densely Functionalized<i>N</i>-Hydroxypyrroles Mediated by Vinyltriphenylphosphonium Salt

Abstract

Abstract Protonation of the reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxlates by butane-2,3-dione monoxime leads to vinyltriphenylphosphonium salts, which undergo intramolecular Wittig reaction to produce dialkyl 2,3-dimethyl-N-hydroxypyrrole-4,5-dicarboxylates in fairly high yields.