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)‐1 H ‐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.