Cp*Rh(III)‐Catalyzed Divergent Synthesis of N‐heterocycles with N‐methoxyindoleamides and Isoxazolones

A method for synthesizing pyrimido[1,2‐a]indol‐4‐ol heteroarenes via a Cp*Rh(III)‐catalyzed cascade C‐H activation/annulation strategy employing N‐methoxyindoleamides and isoxazolones is developed. Also, a framework of 3‐methoxy‐2,3‐dihydro‐[1,3,5]triazino[1,2‐a]indole‐4,10‐dione was successfully synthesized via a Cp*Rh‐catalyzed C‐H activation/annulation/oxidation reaction between N‐(methyloxy)‐1H‐indole‐1‐carboxamide and isoxazolones. These reactions demonstrated the suitability of several substrates, compatibility with numerous functional groups, and mild reaction conditions. Preliminary mechanistic investigations have been completed.