Phosphorus-Involved Wagner–Meerwein Rearrangement of Phosphiranes: An Entry to Four-Membered Phosphacycles

Phosphenium ions [R2P]+ are important and highly reactive dicoordinate phosphorus species. Herein, we report a rearrangement of the carbocation into the phosphenium cation driven by ring strain. This phosphorus-involved Wagner–Meerwein rearrangement pathway converted the 1-acylphosphirane complex into phosphetane and 1,2-dihydrophosphete derivatives depending on the reaction temperature. The generation of the intermediate phosphenium cation was identified by the intramolecular reaction with ether, which also disclosed its strong Lewis acidity. This work expands the boundary of the phosphorus–carbon analogy.