PURPOSE: To obtain an antibacterial compd. having a 3-aminopyrrolidin-1-yl group introduced thereinto at a 7-position thereof by converting OH of 3- hydroxypyrrolidine wherein N-1 is protected to a substituted amino group and reacting the obtained compd. with a 1,8-naphthylidine derivative.

CONSTITUTION: OH of 3-hydroxypyrrolidine wherein N-1 is protected is converted to a cleavable group to be converted to an amine through an N- nucleophilic reagent and this amine group is protected by an N-protective group R4 to obtain a compd. represented by formula I and this compd. is reacted with 7-chloro-1-(o,p-difluorophenyl)-1,4-dihydro-6-fluoro-4-oxo-1,8-naphthilidine-3- carboxylic acid or ethyl ester thereof to decompose an R4-substituent to obtain a compd. represented by formula II.