2.2 g of cystamine dihydrochloride were dissolved in 20 ml of water and adjusted to pH 10 with NaOH. 2.1 g of p-azidobenzenesulfochloride were suspended in the solution and the mixture was stirred at room temperature for 5 hours. The precipitated N-(p-azidobenzenesulfonyl)cystamine was reacted with 2 g of succinic anhydride and stirred overnight. The resulting solution was acidified with HCl and the product was subsequently filtered off and washed with water. The residue was dried at room temperature in a high vacuum and gave 1.53 g of N-(p-azidobenzenesulfonyl)-N'-(3-carboxypropionyl)cystamine. The IR showed bands at 3283 (amide NH), 2134 (azide), 1714 (acid carbonyl), 1650 (amide), 1589+1547 (aromatic), 1284 (COOH), 1328+1180 (arylsulfonyl), 839 (p- disubst. benzene); TLC (silica gel: conc. NH3 (EtOH=1%). Rf=0.7; m.p. 163° (dec.).
