The present invention relates to a compound of formula (I)or a pharmaceutically acceptable salt thereof wherein X and R are as defined herein. The compounds of formula (I) are useful as gyrase and/or topoisomerase IV inhibitors for treating bacterial infections. The compounds of formula (I) either possess a broad range of anti-bacterial activity and advantageous toxicological properties or are prodrugs of compounds having said activity.本發明係關於一種式(I)化合物或其醫藥學上可接受之鹽,其中X及R如本文所定義。該等式(I)化合物適用作用於治療細菌感染之旋轉酶及/或拓撲異構酶IV抑制劑。該等式(I)化合物具有廣泛範圍之抗細菌活性及有利之毒理學特性或為具有該活性之化合物的前藥。