Patent ID: 7615554

Claim:
A compound having a structure of Formula V or a pharmaceutically acceptable salt thereof, wherein R 1 is selected from H and C 1-8 alkyl; R 2 is selected from H and C 1-8 alkyl wherein C 1-8 -alkyl is optionally substituted by one or more of hydroxyl, halo, cyano, alkoxy, nitro, carbonyl, thiocarbonyl, phosphoryl, phosphate, phosphonate, phosphinate, amino, amido, amidine, imine, azido, sulfhydryl, alkylthio, sulfate, sulfonate, sulfamoyl, sulfamido, sulfonyl and heterocyclyl; R 3 is selected from alkoxy and unsubstituted C 1-8 alkyl; R 4 is selected from H, alkoxy and unsubstituted C 1-8 alkyl; R 5 is selected from H, halogen; and n is 1 or 2.