HOBt·DCHA-Mediated Synthesis of Sterically Hindered Peptides employing Fmoc-Amino Acid Chlorides in Both Solution-Phase and Solid Phase Methods

Abstract

The synthesis of peptides employing Fmoc-amino acid chlorides in presence of HOBt·DCHA salt in solution as well as by the solid-phase methods is described. The coupling was found to be complete in 30 min and free from racemization. The synthesis of β-casomorphin by solid-phase protocol employing Fmoc-amino acid chloride/HOBt·DCHA in DMF–CH₂Cl₂ has also been outlined. The final peptide was obtained in 80% yield and was fully characterized.

Keywords:

• Fmoc-amino acid chloride
• fmoc-amino acid-OBt ester
• HOBt·DCHA

ACKNOWLEDGMENTS

We are grateful to the Department of Science and Technology, Government of India, for financial support. We thank Professor Fred Naider, City of University of New York (CUNY), New York, for useful discussions and S. I. F, and M. B. U. of Indian Institute of Science (IISc), Bangalore, for providing NMR and mass facilities.