A Sonochemical Approach to 3-(het)aryl Substituted 1H-[1,3]oxazino[3,4-a]indol-1-One Derivatives Promoted by Pd/Cu-Catalysts and ZnCl2

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Peer-Reviewed Article

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A new approach has been developed for the access of 3-(het)aryl substituted 1H-[1,3]oxazino[3,4-a]indol-1-one derivatives promoted by Pd/Cu-catalysts and ZnCl2. These compounds were prepared via a direct and one-pot method involving the coupling of 2-iodoindole derivatives with a range of terminal alkynes in the presence of (PPh3)4Pd, CuI and ZnCl2 in DMF under ultrasound. This sonochemical approach proceeded via the CC coupling followed by intramolecular cyclization (i.e. CO bond formation) in a regioselective manner in the same pot affording the desired products in good to acceptable yield. The mild reaction conditions, shorter duration and the use of eco-friendly energy are some of the key features of the current methodology. Among the synthesized compounds, the [1,3]oxazino[3,4-a]indol-1-one derivative 3a, 3c and 3f were identified as the preliminary hits when tested in vitro for their TNF-α inhibitory potential.