Caprazene and caprazol could be synthesized by hydrolysis of a caprazamycin. There could be synthesized a caprazene-1'''-amide derivative of the formula (II) ##STR00001## and a caprazene-1'''-ester derivative of the formula (III) ##STR00002## from caprazene. Further, there could be synthesized a caprazol-1'''-amide derivative of the formula (V) ##STR00003## and a caprazol-1'''-amide-3'''-ester derivative and a caprazol-3'''-ester derivative, etc. from caprazol. Furthermore, an imidazolidinone derivative could be synthesized from the ring-opened product of the 1,4-diazepinone ring of caprazol.The novel caprazene derivative, novel caprazol derivative and novel imidazolidinone derivative now synthesized exhibit excellent antibacterial activities against a variety of bacteria, including acid-fast bacteria.