Indole-Functionalized Heterocyclic Molecules: Synthesis and Related Applications (A Review)

Indole heterocycles are one of the most significant scaffolds in biological systems such as neurotransmitter, enzyme inhibition, coordination chemistry, drug discovery, and organic synthesis. It plays an important role in cell biology, and the utility of indole and its derivatives for the treatment of cancer cells, various kinds of disorders in the human body, and microbes has attracted insightful attention in past decades. Several FDA-approved drugs based on indole scaffolds such as frovatriptan, zolmitriptan, almotriptan, melatonin etc. for the treatment of nervous system are running in the market as well as several indole-based scaffolds are under clinical trial in different phases. Due to the significance of the indole scaffold, the study of novel approaches for the preparation has drawn the attention of the chemical community. This review primarily focused on the classical and modern synthetic methodology of indole and its derivatives, their mechanisms, biological and other applications, such as chemo-sensors, fluorescence probes, etc.