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Heterocyclic molecules exhibit significant importance as they possess pharmacological, biological, and industrial applications. Although several excellent synthetic routes have been established for heterocyclic molecules, sustainable synthetic procedures such as microwave, ultrasound, grinding, photochemical, and thermodynamic route maps are needed to be explored further. Furthermore, these techniques become more eco-compatible when they produce value-added products in the absence of solvent. The advantages of these methodologies are to generate a library of small molecules, which will eventually combine to form complex bioactive molecules. In this review, we have emphasized recent studies (2010 to 2022) on the solvent-free conditions of various heterocycles (N, O, S), which have been synthesized via oxidation, reduction, condensation, and conjugated reactions. In this literature survey, glimpses of methodologies with their advantages, mechanistic considerations, and limitations are highlighted. These sustainable, and economically feasible routes will pave the way for a revolutionary corridor in the near future. [ABSTRACT FROM AUTHOR]

Ammonium thiocyanate-promoted simple, rapid and eco-friendly neat synthesis of isothiazoles is developed for the first time. It is noteworthy that an instantaneous valuable synthetic route of β-enaminones is also documented during the mechanistic investigation of isothiazole formation. A detailed mechanistic explanation of the isothiazole formation reaction is clearly explained by the control experiments. NBS-promoted aromatisation of isothiazole derivatives and photophysical properties of an isothiazole-pyrene hybrid molecule have been investigated. [ABSTRACT FROM AUTHOR]

Isoindolinones are the core structures of many natural products and drug molecules and are useful in materials science as fluorescent probes and synthetic dyes. The fused analogues of these blended lactams also have a wide range of applications in medicinal chemistry and chemical biology. Different synthetic approaches and the use of versatile reagents have been reported for the synthesis of these novel molecules. Different research groups have focused their efforts on improving synthetic protocols towards the synthesis of the isoindolinone frame both in the presence and absence of transition metals. However, the transition metal-based pathway requires hazardous conditions, which are toxic to the environment. In particular, the transition metal-free synthetic protocols for isoindolinones and their fused analogues are highly fascinating due to several advantages for the industrial production of these bio-active molecules. These concepts encouraged us to write this review to highlight the recent advancements in the synthetic methods involving transition-metal-free approaches from 2007 to 2021. As the main feature of this review, we summarize the synthetic pathways for the isoindolinones, highlighting the synthetic precursors, which include different ortho-substituted aromatic substrates via multistep or tandem protocols, under metal-free conditions. We also discuss the mechanistic pathway of each methodology for the formation of isoindolinones. [ABSTRACT FROM AUTHOR]

An easy green synthetic approach for fused isoindoloquinazolinones has been developed under neat reaction (yields up to 91%) conditions. This new one-pot tandem methodology involves condensation of readily available anthranilamide with 3-(2-formylcycloalkenyl)-acrylic ester under solvent- and catalyst-free conditions. This strategy avoids the use of oxidant, and heavy metal catalysts and also is free from work-up and generation of toxic by-products. A dramatic change of photophysical properties of dihydroisoindoloquinazolinones in basic and aqueous media has also been documented in our study. Moreover, our model synthetic compound shows cytotoxic activity towards metastatic HepG2 and PC3 cancer cell lines. [ABSTRACT FROM AUTHOR]

Correction for 'Recent developments in the solvent-free synthesis of heterocycles' by Nilabrata Dey et al., New J. Chem., 2023, https://doi.org/10.1039/d3nj01991h. [ABSTRACT FROM AUTHOR]