Multifunctional 1,3-diphenylguanidine for the carboxylative cyclization of homopropargyl amines with CO₂ under ambient temperature and pressure

Herein, we report that 1,3-diphenylguanidine (DPG) could be utilized for the carboxylative cyclization of homopropargyl amines with CO₂ under ambient temperature and pressure, in combination with AgSbF₆, which enabled the synthesis of both chiral and achiral 2-oxazinones efficiently. A mechanistic study revealed that the multi-functionality of DPG is critical to the success of the reaction.