One-Pot Synthesis of 4-Chloroquinolines via Bis(trichloromethyl) Carbonate and Triphenylphosphine Oxide-Mediated Cascade Reactions of N-Aryl Enaminones

A novel method for synthesizing substituted 4-chloroquinolines has been devised, utilizing a cascade reaction of N-aryl enaminones promoted by bis(trichloromethyl) carbonate (BTC) and triphenylphosphine oxide (TPPO). This approach features accessible starting materials, a broad substrate range, extensive functional group compatibility, gentle reaction conditions, and straightforward operation. Its versatility is evidenced by its facile scalability and suitability for late-stage derivatization. A plausible mechanism involving α-carbonylation, 6π-azaelectrocyclization, and dehydroxychlorination sequence is proposed.