Synthesis of chemical probes 5–8. Conditions: a) dansyl chloride, DMAP, pyridine, 29%; b) N-Boc-1,3-propanediamine, NaBH(OAc)3, dichloroethane, 95%; c) 4N HCl, dioxane; d) dansyl chloride, triethylamine, dichloromethane, 8% over two steps; e) dansyl chloride, DMAP, pyridine, 14%; f) 1-(hydroxymethyl)cyclohexanol, camphor sulfonic acid, dichloromethane, 72%.