Harnessing Vinyl Acetate as an Acetylene Equivalent in Redox-Neutral Cp*Co(III)-Catalyzed C-H Activation/Annulation for the Synthesis of Isoquinolones and Pyridones

We have developed Cp*Co(III)-catalyzed redox-neutralsynthesisof 3,4-unsubstituted isoquinoline 1(2H)-ones at ambienttemperature using N-chloroamides as a starting material.The reaction utilizes vinyl acetate as an inexpensive and benign acetylenesurrogate. The N-Cl bond of the N-chlorobenzamidesplays the role of an internal oxidant and hence precludes the needfor an external oxidant. The reaction works with a wide range of substrateshaving various functional groups and a substrate containing a heterocyclicring. Notably, the reaction is extended to the N-chloroacrylamidesin which vinylic C-H activation occurs to furnish the 2-pyridonederivatives. Preliminary mechanistic studies were also conducted toshed light on the mechanism of this reaction.

Automated summary

We have developed a redox-neutral synthesis of 3,4-unsubstituted isoquinoline 1(2H)-ones using Cp*Co(III) catalyst and N-chloroamides as starting materials. The reaction is conducted at ambient temperature and utilizes vinyl acetate as a cost-effective and benign acetylene surrogate. The N-Cl bond of the N-chlorobenzamides acts as an internal oxidant, eliminating the need for an external oxidant. The reaction demonstrates broad substrate scope and can also be extended to N-chloroacrylamides, resulting in the formation of 2-pyridone derivatives through vinylic C-H activation.