Sulfonates of N-triazinylammonium salts as highly efficient, inexpensive and environmentally friendly coupling reagents for peptide synthesis

Sulfonates of N-triazinylammonium salts, the family of inexpensive and environmentally friendly Triazine-Based Coupling Reagents (TBCR) was obtained by treatment of 2-chloro-4,6-dimethoxy-1,3,5-triazine with sulfonates of tertiary amines in the presence of sodium bicarbonate. A broad variety of N-triazinylammonium sulfonates can be obtained by this procedure and up to now we demonstrated that they can be useful for activation of carboxylic components, with the activation rate depending on the structure of the tertiary amine component and sulfonic acid counterion. Participation of triazine "superactive ester", fundamental intermediate in condensation step, has been proved in model experiments. Usefulness of this approach was confirmed by peptide synthesis in solution in high yield and low risk of racemization, starting from Z(-), Fmoc(-), and Boc(-) protected substrates.