abstract |
The present invention provides an antibacterial agent of formula (I), or a pharmaceutically acceptable salt thereof, wherein A is the structure (i), (ii), (iii) or (iv); X is (a ) NHC (= O) R 1 , (b) NHC (= S) R 1, (c) NH-het 1, (d) O-het 1, (e) S-het 1, or (f) het 2 It is. [Chemical 1] |