A series of N-hydroxy-3-[3-(1-substituted-1H-benzoimidazol-2-yl)-phenyl]-acrylamides (5a– 5ab) and N-hydroxy-3-[3-(1, 4, 5-trisubstituted-1H-imidazol-2-yl)-phenyl]-acrylamides (12a– s) were designed, synthesized, and found to be nanomolar inhibitors of human histone deacetylases. Multiple compounds bearing an N1-piperidine demonstrate EC50s of 20– 100nM in human A549, HL60, and PC3 cells, in vitro and in vivo hyperacetylation of ...