Synthesis of 3,3-Spirocyclic-2-Phosphono-Indolines via a Dearomative Addition of Phosphonyl Radicals to Indoles

We report the diastereoselective synthesis of alpha-aminophosphonates derivatives embedded in a spirocyclic indolines. Our method proceeds via the dearomative addition of phosphonyl radicals at the C2-position of the indole nucleus in oxidative conditions followed by the intramolecular trapping of the resulting carbocation before rearomatization. trans-3,3-Spirocyclic-2-phosphonoindolines were thus obtained.