Concerning a simple method for preparing an avibactam intermediate, a compound of formula III is used as a raw material, and is hydrolyzed in the presence of an alkali to obtain a compound of formula IV by acidification, and the resulting compound of formula IV is simultaneously subjected to cyclic ureation together with triphosgene or diphosgene. To give the compound of formula V, followed by amidation to give the final product (II). Since the cyclic ureation, chlorination acylation, and amidation are completed by the "one-pot method", there is no need to perform separation and purification into intermediate products. The raw materials are inexpensive and readily available, the process is simple, the operability is high, no special protective agents and carbonylating reagents are required, the atoms to react are economical, the cost is low, and the production process is environmentally friendly. Gentlely, the obtained product (II) has a high purity and a high yield, which is advantageous for cost reduction of avibactam (I) and its green production. [Selection diagram] Noneアビバクタム中間体の簡便な調製方法に関し、式ＩＩＩ化合物を原料とし、アルカリの存在下にて加水分解され、酸性化により式ＩＶ化合物を得、得られる式ＩＶ化合物をトリホスゲン又はジホスゲンと共に同時に環状尿素化と塩化アシル化させ、式Ｖ化合物を得、次にアミド化により最終生成物（ＩＩ）を得る。環状尿素化、塩化アシル化及びアミド化は「ワンポット（one-pot）方法」により完成するものであるため、中間生成物への分離、精製を行う必要がない。原料は安価で入手しやすく、プロセスが簡潔であり、操作性が高く、特殊な保護剤及びカルボニル化試薬が不要であり、反応する原子は経済性が高く、コストが低く、生産プロセスにおいて環境に優しく、得られる生成物（ＩＩ）は純度も収率も高く、アビバクタム（Ｉ）のコストダウン及びそのグリーン生産に有利である。【選択図】なし
