Compounds of formula (I) or pharmaceutically acceptable salts thereof are provided: wherein: A is alkylenyl of 1 to 4 carbon atoms, or alkenylenyl of 2 to 4 carbon atoms; R1 and R2 are, independently, hydrogen or a C5 to C7 aryl optionally substituted with 1 to 2 substituents, independently, selected from the group consisting of —C(O)R3, halogen, cyano, nitro, hydroxyl, C1-C6 alkyl, and C1-C6 alkoxy, with the proviso that at least one of R1 and R2 is not hydrogen; R3 is, independently, hydrogen, —OR4, alkyl, aryl, or heteroaryl; R4 is hydrogen, alkyl, aryl, or heteroaryl; R5 and R6 are, independently, hydrogen, alkyl, hydroxyl, alkoxy, or C5 to C7 aryl; wherein any R3 to R6 group having an aryl or heteroaryl moiety can optionally be substituted on the aryl or heteroaryl moiety with 1 to about 5 substituents, independently, selected from the group consisting of halogen, cyano, nitro, hydroxyl, C1-C6 alkyl, and C1-C6 alkoxy. Methods of making these compounds as well as methods using the compounds for treating a variety of conditions are also disclosed.