Zwitterionic Ring-Opened Oxyphosphonium Species from the Ph3P–I2 Mediated Reactions of Benzo[d]oxazol-2(3H)‑ones with Secondary Amines

Instead of the expected substituted 2-aminobenzo­[d]­oxazoles, relatively stable ring-opened oxyphosphonium betaines were isolated for the first time from the Ph3P–I2-mediated reactions of benzo­[d]­oxazol-2­(3H)-ones with acyclic secondary amines. The structure of one of these compounds was unambiguously confirmed by single-crystal X-ray analysis. Thermolysis of the betaines gave rise to 2-dialkylaminobenzoxazoles with concomitant loss of triphenylphosphine oxide, suggesting their possible role as intermediates in an alternative reaction path.