Triethylamine → Amino-1-ethoxycarbonyl piperidine

Ethyl 4-amino-1-piperidinecarboxylate (300 mg) and triethylamine (258 mg) were dissolved in 5 ml of dichloromethane. To the mixture, 2 ml of solution of t-butylsulfinyl chloride (222 mg) in dichloromethane was added and the mixture was stirred at room temperature for 4 hours. The solution was partitioned into an aqueous solution of potassium hydrogen sulfate and ethyl acetate. The organic layer was washed with brine and dried over magnesium sulfate anhydride. The solvent was removed under reduced pressure and the residue was purified by silica gel chromatography to give 378 mg of 4-t-butylsulfiny amino-1-ethoxycarbonyl piperidine.