One-pot synthesis of Weinreb amides employing 3,3-dichloro-1,2-diphenylcyclopropene (CPI-Cl) as a chlorinating agent

Abstract

The synthesis of N^α-protected amino alkyl Weinreb amides starting from the corresponding α-amino acids as well as carboxylic acids has been delineated through the in situ generation of acid chlorides using CPI-Cl as a chlorinating agent. The protocol is simple; the reaction conditions employed were mild, and compatible with all the three commonly used urethane protecting groups namely, Boc, Cbz and Fmoc groups. The resulting Weinreb amides are obtained in good yields as optically pure products.

Graphical Abstract

Keywords:

• Acid chloride
• CPI-Cl
• N^α-protected amino alkyl Weinreb amides
• N,O-dimethylhydroxylamine

Acknowledgment

One of the authors, Roopesh Kumar. L, thanks DST-Nano Mission for fellowship.

Additional information

Funding

We are grateful to acknowledge the financial support from UGC-NFSC and SERB, New Delhi, Government of India.