Reaction of Phospholes with Aldimines: A One-Step Synthesis of Chelating, Alpha‑C₂‑Bridged Biphospholes

Phospholes react with aldimines at 170 °C in the presence of mild Lewis acids to give C2-bridged biphospholes in good yields. The mechanism includes a series of [1,5] shifts of the P-substituents around the phosphole ring, a P–H + aldimine condensation, and the formation of a transient three-membered ring that dimerizes.