A one-step procedure for efficient synthesis of oxazolidinone only using ethylene carbonate and arylamines in the presence of 1,4-diazabicyclo[2,2,2]octane (DABCO) was developed. In most cases, moderate to high yield of products were obtained. This reaction can be considered a carbon dioxide fixation reaction since ethylene carbonate was synthesized via reaction of ethylene oxide with carbon dioxide.