Cp*Co(III) catalyzed annulation of N-Cbz hydrazones for the redox-neutral synthesis of isoquinolines via C–H/N–N bond activation

Abstract

A new cascade oxidative cyclization reaction of N-Cbz hydrazones with internal alkynes has been explored for the preparation of isoquinoline derivatives using Cp*Co^III-catalyst through C–H and N–N bond functionalization. N-Cbz hydrazones are rarely explored as directing group for redox-neutral [4 + 2] cyclization reaction through the cyclometallation and this catalyst system does not require any external oxidizing agent, as well as, silver or antimony salt. The current efficient approach has been utilized for the synthesis of different isoquinoline derivatives with good regioselectivity and yields.

Graphical Abstract

Keywords:

• C–H/N–N bond activation
• cobalt
• N-Cbz hydrazone
• silver salt-free

Additional information

Funding

The author D.D.S. would like to thankful to the University Grant Commission (UGC), New Delhi, Govt. of India for providing financial support under the Dr. D. S. Kothari Post Doctoral Fellowship Scheme [No.F.4-2/2006 (BSR)/CH/16-17/0210]