Rh(III)-Catalyzed Chemoselective [4 + 2] Annulations for the Synthesis of [1,3]Oxazinoindolones: A Combined
Perla Bharath Kumar1,2, Chittala Emmaniel Raju1,2, Saikat Roy3
1Fluoro and Agrochemicals Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India.
Abstract:
The interaction of N-alkoxy-1H-indole-1-carboxamides with transition metals leads to indole-fused heterocyclic scaffolds through directing group leaving/migration, [3 + 2], N-C2 [4 + 1], and [4 + 2] annulations. However, the corresponding O-C2 [4 + 2] annulation reactions have never been reported. Herein, we report the chemoselective annulation of N-alkoxy-1H-indole-1-carboxamides catalyzed by Rh(III), affording [1,3]oxazinoindolones through a hitherto unknown reaction pathway. This unprecedented C2 oxygen cyclization, rather than the known C2 nitrogen cyclization to form oxazinoindolones via five key steps, has been explained using density functional theory.
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