2-(4-Sulfophenylsulfonyl)ethoxycarbonyl group: a new water-soluble N-protecting group and its application to solid phase peptide synthesis in water

Solid phase peptide synthesis is carried out in organic solvents, creating environmental problems after disposal. To avoid this problem, we aimed to perform solid phase peptide synthesis in water. A new water-soluble N-protecting group, 2-(4-sulfophenylsulfonyl)ethoxycarbonyl (Sps) group, was designed and Sps-amino acids were prepared. To evaluate the utility of this technique, Leu-enkephalin amide was prepared by solid phase synthesis using Sps-amino acids in water.