Metal‐Free One‐Pot Domino Synthesis of Oxazolidinone Derivatives

A metal‐free approach for the synthesis of iodomethylene‐oxazolidin‐2‐one from easily accessible propargylic alcohols, aryl isocyanates, and molecular iodine in presence of base is reported. Propargylic carbamates are generated in situ in presence of iodine and triethylamine which underwent iodocyclization to afford oxazolidinone scaffolds in good to excellent yields. The use of mass spectrometry to probe the mechanism showed evidence of a propargylic carbamate‐iodonium intimate ion‐pair intermediate, based on which a reaction mechanism is proposed. This is the first report of a simple room‐temperature synthesis of oxazolidinone derivatives precluding expensive noble metal catalysts and oxidants. A novel base catalyzed reaction of propargylic alcohols, aryl isocyanates, and molecular iodine for the synthesis of oxazolidinone derivatives in 2‐MeTHF has been developed. The reaction mechanism was proposed based on MALDI ESI, COSY, and NOESY analysis, which showed evidence for the formation of a propargylic carbamate‐iodonium intimate ion‐pair intermediate.