Abstract:: Indole moiety is often found in different class of pharmaceutically active molecules having various biological activities including anticancer, anti-viral, anti-psychotic, anti-hypertensive, anti-migraine anti-arthritis and analgesic activities. Due to enormous applications of indole derivatives in pharmaceutical chemistry, a number of conventional synthetic methods as well as green methodology have been developed for their synthesis. Green methodology has many advantages including high yields, short reaction time, and inexpensive reagents, highly efficient and environmentally benign over conventional methods. Currently, the researchers in academia as well as in pharmaceutical industries have been developing various methods for the chemical synthesis of indole based compounds via green approaches to overcome the drawbacks of conventional methods. This review reflects last ten years developments of the various greener methods for the synthesis of indole derivatives by using microwave, ionic liquids, water, ultrasound, nanocatalyst, green catalyst, multicomponent reaction and solvent-free reactions etc. (please see the scheme below). Furthermore, the applications of green chemistry towards developments of indole containing pharmaceuticals and their biological studies have been represented in this review.

Tetragonal zirconia (t‐ZrO2) nanoparticles (NPs) were successfully synthesized by a green method using β‐cyclodextrin as stabilizer. The structural characterization of the prepared nanoparticles was done by X‐ray diffraction (XRD).The tetragonal crystalline structure of ZrO2 NPs was confirmed by XRD analysis. We employed the Rietveld method to refine the XRD data and the refinement result leads to specify the tetragonal phase of ZrO2 NPs with space group P 42/n m c. The FTIR spectrum gives the information about the presence of Zr−O bonding at 501 cm−1. Particle size and morphological properties were demonstrated by Scanning Electron Microscope (SEM) and elemental compositions were analysed using EDAX spectrum. The band gap energy was estimated using optical absorption spectroscopy and the value was found to be 3.99 eV. The UV (310 nm) and visible (401, 420 and 560 nm) emissions were observed from PL spectrum. Brunauer‐Emmet‐Teller (BET) surface analysis was used for determining the surface area and average pore size of ZrO2 NPs.The photocatalytic degradation of the prepared ZrO2 NPs for organic dyes had been studied under visible light irradiation. Results showed that 68 % degradation was achieved within 135 min for Methylene Blue (MB) dye but other dyes almost remains unchanged during the same reaction times.

The synthesis of organofluorine compounds plays a vital role in the field of pharmaceuticals, agrochemicals, and materials since the fluorine-containing compounds have shown improved biological and physicochemical properties. Significant research has been directed towards synthesizing organofluorine compounds because organofluorine compounds have been displayed in several biological activities, including anticancer, antitumor, antihypertensive, antidepressant, anti-HIV and treatment of stroke. Due to several pharmaceutical applications of organofluorine compounds, numerous conventional as well as green synthetic methodologies have been developed for the synthesis of fluorine-containing compounds. However, particularly, the synthesis of organofluorine compounds using green approaches has been continuously attracting research interest since green approaches have several advantages, including the use of inexpensive and nontoxic reagents, catalytic, highly efficient, short reaction time, energy efficient, high reaction yields, and environmentally benign over the conventional methods. Among the green tools, the use of microwave-assisted synthesis, water, and ionic liquids as green solvent/reaction media, organocatalysts, photocatalysts, and solvent-free and catalyst-free reaction conditions have been exploited in the past decades for the synthesis of organofluorine compounds. In this review, we highlighted the recent developments in various green methods for the synthesis of organofluorine compounds via electrophilic fluorination for synthesis of various fluorohydrins, fluorinated acyclic & cyclic β-ketoesters, 1,3-dicarbonyl compounds, cyclic and acyclic ketones, α-cyanoesters, α-aryl-tetralones, α-amino acids, flavanones, and several fluorinated heterocycles such as fluorinated pyridine, pyrimidine, pyrrole, pyrazolone, benzofuran, indole, flavanone, and coumarin derivatives. In addition, some green methodologies have been highlighted for the synthesis of biologically active fluorinated compounds, including HIV-1 integrase inhibitors, 20-deoxy-20-fluorocamptothecin, fluorinated estrone, sclareolide, BMS-204352 (MaxiPost), fluorinated naproxen and fluoxetine.