A mild and sequentially Pd/Cu-catalyzed domino synthesis of acidochromic Indolo[3,2-a]carbazoles – Free bases of apocyanine dyes

Indolo[3,2-a]carbazoles as Engineered Materials for Optoelectronic Applications: Synthesis, Structural Insights, and Computational Screening

“…While wide-spanning applications of indolocarbazoles in multiple domains starting from biology to medicine to electronics are quite evident, the major challenges are associated with their synthesis processes as the reported synthetic routes are restricted with some or other issues that include multistep processes, long reaction time, the requirement of prefunctionalized starting substrates, need of inert atmospheres and dry solvents, use of high-boiling solvents, employment of metal oxidants, and so on. Since the first report on the synthesis of indolo­[3,2- a ]­carbazoles in 1951, a few nice approaches have been reported for the development of a diverse range of functional indolo­[3,2- a ]­carbazoles. − ,− Among those, the one-pot processes have gained good attention considering the economic aspects and operational simplicity. ,, To mention a few, Nair and co-workers reported a fascinating acid-catalyzed approach for reacting 1,2-diketone with indoles to produce indolo­[3,2- a ]­carbazoles in the presence of dry solvent under an argon atmosphere (Scheme ). Later, another interesting Pd­(II)-catalyzed process was developed by Zhao and co-workers for synthesizing functional indolo­[3,2- a ]­pyrrolo­[3,4- c ]­carbazole-6,8-diones, outperforming some of the reported methods (Scheme ), in the presence of (Cu­(OAc) 2 ) as an oxidant, and using DMF and DMSO as solvents .…”