Highly Efficient Coupling of β-Substituted Aminoethane Sulfonyl Azides with Thio Acids, toward a New Chemical Ligation Reaction

[reaction: see text] A highly efficient coupling of protected beta-substituted aminoethane sulfonyl azides with thio acids is reported. In the case of peptide thio acids, this method encompasses a new chemoselective ligation method. Furthermore, the resulting alpha-amino acyl sulfonamides can be alkylated with suitable electrophiles to obtain densely functionalized sulfonamide scaffolds.