Cobalt(III)-Catalyzed [4 + 2] Annulation of N-Chlorobenzamides with Maleimides.

A Co(III)-catalyzed novel [4 + 2] annulation of N-chlorobenzamides with maleimides has been reported. Mostly, maleimides are known to furnish the Michael-type or 1,1-type cyclized products while treating with amides. In this reaction, maleimides furnished [4 + 2] annulated products in good yields at room temperature while being treated with the internal oxidizing N-chlorobenzamide as a directing group. The developed methodology is compatible with a variety of functional groups. The [4 + 2] annulated products obtained are featured in some biologically active molecules.