This invention relates to compounds for the inhibition of histone deacetylase. More particularly, the invention provides for compounds of formula compounds of the Formula (I) and N-oxides, hydrates, solvates, pharmaceutically acceptable salts, prodrugs and complexes thereof, and racemic and scalemic mixtures, diastereomers and enantiomers thereof, wherein groups L, M, X and Y are as defined herein.本發明係關於抑制組蛋白去乙醯酶之化合物。更特定言之,本發明係提供式(I)化合物及其N-氧化物、水合物、溶劑合物、藥學上可接受之鹽、前體藥物及複合物,及其外消旋與呈比例混合物、非對映異構物及對掌異構物,其中基團L,M,X及Y均如本文定義。