I2-DMSO-Mediated In Situ Capture of Ketenimine Cations by Two Molecules of 3-Aminoindazole for the Synthesis of 1-(1H-Indazol-3-yl)-2,4-Diphenyl-1H-Pyrrolo[2',3':4,5]Pyrimido[1,2-b]Indazole Derivatives.

An I2-DMSO-mediated, one-pot synthesis of 1-(1H-indazol-3-yl)-2,4-diphenyl-1H-pyrrolo[2',3':4,5]pyrimido[1,2-b]indazole derivatives using 3-aminoindazoles, acetophenones, and enaminones as starting materials has been developed. The key to realizing this process lies in the multiple trapping of the in situ generated ketenimine cation by the two molecules of 3-aminoindazole. The structure of the compound was determined through X-ray single-crystal experiments, and the study expanded to include 40 compounds. Spectroscopic studies showed that the selected compounds have maximum absorption at 443-490 nm and maximum emission at 543-574 nm with quantum yields of 0.07-0.24.