Patent ID: 8227636

Claim:
A compound represented by the structure of formula 1: wherein R is a residue of a hydroxamic acid derivative histone deacetylase inhibitor; and R a is represented by the structure: wherein R b is a hydrogen or an unsubstituted or substituted ethyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, alkynyl, naphthyl, cycloalkyl, heterocyclyl, heteroaryl, alkylaryl, alkylcycloalkyl, alkylheterocyclyl, alkylheteroaryl or an amino acid residue; R c is a hydrogen or an unsubstituted or substituted alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, alkylaryl, alkylcycloalkyl, alkylheterocyclyl, alkylheteroaryl or an amino acid residue and R d is hydrogen or an amino protecting group; or a pharmaceutically acceptable salt thereof.