Disclosed herein is a compound of Formula II below: OH wherein R.sub.1 is a p-nitrobenzyl or p-methoxybenzyl, group; and R.sub.2 and R.sub.3 may be identical to or different from each other and are each independently a C.sub.1-6alkyl or aryl group, or a derivative thereof, and a process for preparing the compound of Formula II. Further disclosed is a process for preparing imipenem of Formula I below: by using the compound of Formula II.