Synthesis of Cyclopentenes, Pyrroles, and Thiophenes via a Sequence of Propargyl–Allenyl Isomerizations, Michael Additions, and Intramolecular Wittig Reactions

Allenylphosphonium species, reactive Michael acceptors, could be generated from simple, readily available propargylphosphonium salts through propargyl–allenyl isomerization. We developed an efficient synthesis for cyclopentenes, pyrroles, and thiophenes via a sequence of propargyl–allenyl isomerizations, Michael additions, and intramolecular Wittig reactions.