An efficient and practical approach for the synthesis of indoloquinolines and indolo/pyrroloquinoxalines via a Cu-catalyzed Ugi-C/Ugi- N -arylation sequence.

A Cu-catalyzed tandem transformation of Ugi adducts through CH/NH bond functionalization reactions was reported for synthesizing a broad spectrum of indolo/pyrrolo-[1,2- a ]quinoxaline-6/4-carboxamide, 7 H -indolo[2,3- c ]quinoline-6-carboxamide, and 1-(cyclohexylamino)-14 H -indolo[2,3- c ][1,4]oxazino[4,3- a ]quinolin-4(3 H )-one derivatives in moderate to excellent yields. In this protocol the Ugi condensation of aromatic aldehydes, anilines, acids, and isocyanides leads to the formation of bis-amides in methanol at room temperature. This approach employed simple reaction conditions, including Ugi product as starting material, CuI, l-proline as a ligand, and cesium carbonate, in DMSO for 8 h. This method demonstrated efficiency in synthesizing fused-nitrogen-containing heterocycles through a convenient pathway.
Competing Interests: The authors declare no conflicts of interest.
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