BEETAARAKUTAMUJUDOTAINOSEIZOHOHO

摘要

The invention provides a process for preparing a beta -lactam derivative represented by the formula the process comprising reacting a beta -lactam derivative represented by the following formula (II) and having a protected carboxyl group with a cresol; wherein R represents a benzyl group having an electron-donating group as a substituent on the phenyl ring, a diphenylmethyl group which may have an electron-donating group as a substituent on the phenyl ring or a tert-butyl group.