Atmospheric Pressure of CO2 as Protecting Reagent and Reactant: Efficient Synthesis of Oxazolidin‐2‐ones with Carbamate Salts,Aldehydes and Alkynes

Carbon dioxide (CO₂) has been wildly employed as an environmentally benign C₁ resource for organic synthesis in the recent years. The capture of CO₂ with primary amines easily provides the corresponding carbamate salts. We described herein that carbamate salts are a useful reactant for the synthesis of oxazolidin‐2‐ones via the reaction with aromatic aldehydes and aromatic terminal alkynes. A variety of oxazolidin‐2‐ones with different functional groups were synthesized in 68–91% yields with only a 5 mol% amount of CuI as catalyst. It was found that the synergetic effect of iodide is important for the transformation. Notable, the captured CO₂ serves not only as a protecting reagent for electron‐rich primary amine to avoid catalyst poisoning, but also as a reactant for the construction of oxazolidin‐2‐ones.