Addition of HOAt dramatically improves the effectiveness of pentafluorophenyl-based coupling reagents

• Published in: Tetrahedron letters Vol. 40; no. 11; pp. 2045 - 2048
• Main Authors: Klose, J., El-Faham, A., Henklein, P., Carpino, L.A., Bienert, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 12-03-1999
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/S0040-4039(99)00089-1

In the course of comparing the effectiveness of several HOAt- and HOPfp-derived coupling reagents by cyclization and segment condensation of model sequences, using HPLC to follow the time course and to determine the outcome in terms of oligomerization and epimerization, we found a striking improvement of the less effective HOPfp-based coupling reagent (HPyOPfp), both with regard to reaction rate and extent of epimerization, when HOAt was added.
Comparison of the effectiveness of HOAt- and HOPfp-derived coupling reagents and the dramatic influence of HOAt upon peptide cyclization and segment condensation in the HOPfp case.