Provided are a compound represented by Formula (I): wherein R 1 , R 2 , R 3 , and R 4 are each independently selected from a hydrogen atom, a C 1-6 alkyl group which may be substituted, a C 7-14 aralkyl group which may be substituted and -C(=O)Rx； n denotes an integer selected from 1 and 2； and ring Ar is selected from the groups represented by the following Formula (a) to (f). , or a prodrug thereof or a pharmaceutically acceptable salt thereof as well as a pharmaceutical agent and a pharmaceutical composition containing such a compound or a prodrug thereof, or a pharmaceutically acceptable salt thereof.經由本發明可提供以式(I)所示化合物、或其藥物前體或藥理學上可被容許之此等之鹽所示化合物、其藥物前體及此等之藥理學上可被容許之鹽、以及含該化合物之醫藥、醫藥組成物等、[式中，R1、R2、R3及R4係分別獨立示選自氫原子、可被取代之C1~C6烷基、可被取代之C7~C14芳烷基、及－C(＝O)Rx；n示選自1及2之整數；環Ar可選自以下式(a)~(f)；所示基者]。
