Transition‐Metal‐Free C‐S Bond Forming Strategy towards Synthesis of Highly Diverse Pyrazole Tethered Benzothiazoles: Investigation of their Photophysical Properties

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, 7H-indolo[2,3-c]quinoline-6-carboxamide, and 1-(cyclohexylamino)-14H-indolo[2,3-c][1,4]oxazino[4,3-a]quinolin-4(3H)-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.

An efficient metal-free and catalyst-free C-S/C-O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

An operationally simple and metal-free approach is described for the synthesis of pyrazole-tethered thioamide and amide conjugates. The thioamides were generated by employing a three-component reaction of diverse pyrazole C-3/4/5 carbaldehydes, secondary amines, and elemental sulfur in a single synthetic operation. The advantages of this developed protocol refer to the broad substrate scope, metal-free and easy to perform reaction conditions. Moreover, the pyrazole C-3/5-linked amide conjugates were also synthesized via an oxidative amination of pyrazole carbaldehydes and 2-aminopyridines using hydrogen peroxide as an oxidant.