Scheme 1. Synthesis of probe TR-H2S. Reaction conditions: (a) 4-(N-Boc-amino)piperidine, EDC·HCl, HOBt; (b) CF3COOH/CH2Cl2; (c) K2CO3, BrCH2CO2C(CH3)3; (d) 4-(diethylamino)salicylaldehyde, MeSO3H; (e) 3, EDC·HCl, HOBt. EDC·HCl = 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, HOBt = 1-hydroxybenzotriazole.
