General procedure for the synthesis of S-trityl-L-cysteamine from (9H-fluoren-9-yl)methyl (R)-(1-amino-1-oxo-3-(triphenylmethylthio)propan-2-yl)carbamate: (R)-(9H-fluoren-9-yl)methyl (1-amino-1-oxo-3-(triphenylmethylthio)propan-2-yl)carbamate (4 g. 6.84 mmol) was dissolved in N,N-dimethylformamide (20 mL), piperidine (0.14 mL, 1.368 mmol) was added and the reaction was carried out for 4 h at room temperature. The progress of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was washed with saturated aqueous sodium chloride solution and subsequently extracted with dichloromethane. The organic phase was dried with anhydrous sodium sulfate, concentrated and purified by column chromatography (eluent: methanol/dichloromethane, 1%-5% gradient) to afford the title product S-trityl-L-cysteamine as a yellow oil (2.3 g, yield: 92%).
