Patent ID: 7923467

Claim:
A compound of the structure of Formula I, or a pharmaceutically acceptable salt thereof, pharmaceutically acceptable tautomer, racemate, pure enantiomer, diastereoisomer or a lactone form or N-oxide thereof, wherein R 1 is C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, or optionally substituted phenyl (wherein up to three substituents are independently selected from halogens, C 1 -C 6 alkyl, cyano, and C 1 -C 3 perfluoroalkyl); R 2 is optionally substituted phenyl (wherein up to three substituents are independently selected from cyano, acetyl, and optionally substituted amino, wherein up to two amino substituents are independently selected from C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, acetyl, and sulfonamide); R 3 is optionally substituted C 1 -C 6 alkyl or C 3 -C 6 cycloalkyl (wherein substituents are independently selected from halogens, hydroxyl, C 1 -C 3 alkoxy and protected hydroxyl); or R 3 is —NR 8 R 9 , wherein R 8 and R 9 are optionally substituted C 1 -C 6 alkyl (wherein the optional substituent(s) is/are selected from halogens, hydroxy, C 1 -C 3 alkoxy and protected hydroxyl); R 4 is wherein R 5 is hydrogen and R 6 is aryl substituted with C 1 -C 6 alkyl substituted with one or two substituents independently selected from hydroxyl and protected hydroxyl with the provisio that R 2 is phenyl only when: R 5 or R 6 is phenyl substituted with hydroxyalkyl.