Selective histone deactylase 6 inhibitors

A method of treating melanoma in a subject, comprising:

• administering to the subject a therapeutically effective amount of a compound having Formula I:
• wherein
• A is C1-C8 alkyl, phenyl, pyridyl, oxazolidyl, or pyrimidyl optionally substituted with one or more groups chosen from C1-C5 alkyl, C1-C4 alkoxy, or halo;
• and
• R1 and R2 are, independently, hydrogen, or are C1-C8 alkyl, C1-C3 alkylaryl, or C1-C3 alkylheteroaryl optionally substituted with acetyl, C1-C5 alkyl, —NR6R7, C1-C4 alkoxy, carbonyl, halo, or hydroxy;
• or
• R1 and R2 are joined such that together they form an alkylene bridge comprising 2 atoms so that a 5-membered ring is formed with the —NC(O)N— moiety, in which case A is as defined above or hydrogen, and which 5-membered ring is optionally substituted with R1′, R2′, R1″, and R2″, which are independently, hydrogen, or are C1-C8 alkyl, C1-C3 alkylaryl, or C1-C3 alkylheteroaryl, any of which is optionally substituted with amino, C1-C4 alkoxy, halo, or hydroxy;
• or R1′ and R1″ together or R2″ and R2′ together form a carbonyl (i.e., ═O);
• or R1′ and R2′ are null and R1″ and R2″ together form a fused phenyl group;
• and
• R6 and R7 are independently H, C1-C4 alkyl, or are joined such that together they form an alkylene bridge comprising 4 or 5 atoms so that a 5 or 6-membered ring is formed with the nitrogen;
• or a pharmaceutically acceptable salt or hydrate thereof.