75179-29-2

General procedure for the synthesis of the compound (CAS: 87242-61-3) from N-hydroxybutanediimide (NHS) and N-tert-butoxycarbonyl-S-trityl-L-cysteine: under argon protection, N-tert-butoxycarbonyl-S-trityl-L-cysteine (4 g, 10 mmol) and NHS (2.25 g, 19.5 mmol) were dissolved in acetonitrile (40 mL) and cooled to 0°C. Subsequently, N,N'-dicyclohexylcarbodiimide (DCC, 4 g, 19.5 mmol) was added to the solution and the reaction mixture was stirred at 0 °C for 2 hours. After that, the reaction mixture was gradually warmed up to room temperature and stirring was continued for 12 hours. Upon completion of the reaction, the resulting dicyclohexylurea (DCU) was removed by filtration and the filtrate was concentrated under vacuum to remove the solvent. The obtained residue was dissolved in ether and filtered again to remove insoluble matter. Finally, the filtrate was concentrated to give the target compound (5 g, 90% yield) as a yellow to light colored foam. The product was characterized by 1H NMR (CDCl3) and MALDI-TOF MS: 1H NMR (CDCl3) δ 1.43 (s, 9H, 3 × CH3), 2.65-2.82 (m, 6H, 3 × CH2), 4.25-4.38 (m, 1H, CH), 5.83 (br s, 1H, NH), 7.15-7.46 ( m, 15H, triphenylmethyl-H); MALDI-TOF MS: m/z 561.8 [M+H]+, calculated molecular weight of C31H32N2O6S is 560.66.

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