Compounds having the structural formula (I) or a pharmaceutically acceptable salt thereof, wherein R is optionally substituted phenyl, cycloalkenyl, or heteroaryl; X is alkylene or -C(O)CH2-;Y is -N(R2)CH2CH2N(R3)-, -OCH¿2?CH2N(R?2¿)-, -O-, -S-, -CH¿2?S-, -(CH2)2-NH-, or optionally substituted,(Ia), m and n are 2-3, and Q is nitrogen or optionally substituted carbon; and Z is optionally substituted phenyl, phenylalkyl or heteroaryl, diphenylmethyl, R?6¿-C(O)-, R6-SO2-, R6-OC(O)-, R7-N(R8)-C(O)-, R7-N(R8)-C(S)-, phenyl-CH(OH)-, or phenyl-C(=NOR2)-; or when Q is CH, (Ib),phenylamino or pyridylamino; or Z and Y together are substituted piperidinyl or substituted phenyl; and R?2, R3, R6, R7, and R8¿ are as defined in the specification are disclosed, their use in the treatment of Parkinson's disease, alone or in combination with other agents for treating Parkinson's disease, and pharmaceutical compositions comprising them; also disclosed are a processes for preparing intermediates useful for preparing compounds of formula (I).