HDAC6-IN-3 (Compound 14), an antiprostate cancer agent, is a potent, orally active HDAC6 inhibitor with IC 50 s ranging from 0.02-1.54 μM for HDAC1/2/3/6/8/10. HDAC6-IN-3 is also an effective MAO-A ( IC 50 =0.79 μM) and LSD1 inhibitor. HDAC6-IN-3 is a click chemistry reagent, it contains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups.