Aqueous hydrotropic solution: green reaction medium for synthesis of pyridopyrimidine carbonitrile and spiro-oxindole dihydroquinazolinone derivatives

High-performance modified LDH for green one-pot synthesis of pyrido[2,3-d]pyrimidines

This study introduces a new nano catalyst tailored for the eco-friendly synthesis of pyrido[2,3-d]pyrimidine via a three-component one-pot reaction involving benzaldehydes, malononitrile, and uracil. To achieve this objective, we anchored copper acetate onto the surface of layered double hydroxides modified with 1,3‑benzenedisulfonyl amide (BDSA) (LDH@PTRMS@BDSA@Cu(NO3)2), which exhibited remarkable activity and selectivity. The main benefits of this method include high product yield, swift reaction times, straightforward purification, catalyst reusability, and the employment of a mild reaction process. Furthermore, the catalyst maintained its effectiveness even after being recycled four times without notable degradation in catalytic performance.

Hydrotrope assisted green synthesis of dicoumarols and in silico and in vitro antibacterial, antioxidant and xanthine oxidase inhibition studies

Aqueous hydrotrope has been employed for the first time to synthesize heteroaryl dicoumarols by condensation of 4-hydroxycoumarin and different heterocyclic aldehydes. This method is highly efficient and green, and the same aqueous hydrotropic solution can be used up to five times without any considerable loss of yield in the product. The synthesized compounds showed good antibacterial potential against Gram-positive (Staphylococcus aureus/NTCC 0997 and B. oceanisediminis) and Gram-negative (Escherichia coli/D0157:H7 and E. coli rosetta) bacterial strains using the Resazurin microtiter plate visual method. The MIC value of 312 µg/ml for compounds 3b, 3k and 3l for S. aureus while 39 µg/ml for compounds 3a, 3b and 3k for E. coli and 625 µg/ml for 3a and 3b for B. oceanisediminis was observed. The compounds were screened via computational methods like molecular docking studies and molecular dynamic simulations with PDB Id's 2W9S and 2EX6. Antioxidant activity was assessed using DPPH and H2O2 assays. Five compounds with the best binding score in molecular docking with XO (PDB ID: 1FIQ) have been tested in an in-vitro study using an enzyme inhibition assay. Novel compound 3b gave the IC50 value of 0.28 µg/ml, comparable to the standard drug Allopurinol.Communicated by Ramaswamy H. Sarma.

Progress in the field of hydrotropy: mechanism, applications and green concepts

Sustainability and greenness are the concepts of growing interest in the area of research as well as industries. One of the frequently encountered challenges faced in research and industrial fields is the solubility of the hydrophobic compound. Conventionally organic solvents are used in various applications; however, their contribution to environmental pollution, the huge energy requirement for separation and higher consumption lead to unsustainable practice. We require solvents that curtail the usage of hazardous material, increase the competency of mass and energy and embrace the concept of recyclability or renewability. Hydrotropy is one of the approaches for fulfilling these requirements. The phenomenon of solubilizing hydrophobic compound using hydrotrope is termed hydrotropy. Researchers of various fields are attracted to hydrotropy due to its unique physicochemical properties. In this review article, fundamentals about hydrotropes and various mechanisms involved in hydrotropy have been discussed. Hydrotropes are widely used in separation, heterogeneous chemical reactions, natural product extraction and pharmaceuticals. Applications of hydrotropes in these fields are discussed at length. We have examined the significant outcomes and correlated them with green engineering and green chemistry principles, which could give an overall picture of hydrotropy as a green and sustainable approach for the above applications.

Recent developments in green approaches for sustainable synthesis of indole-derived scaffolds

An important issue to discover biological structures is the design of sustainable, safe, clean, cost-effective, excellent efficient synthetic reactions, and minimal energy consumption to provide structural diversity compounds with interesting biological properties. Among five-membered nitrogen-containing heterocyclic compounds, indole-containing scaffolds are heterocyclic structures found in abundance in natural products and various synthetic compounds, which have received remarkable attention in recent years due to their therapeutic and pharmaceutical properties and valuable role in the process of drug discovery. Indoles can be synthesized by various procedures although most of these procedures have their own restrictions and drawbacks such as performing the reaction in a toxic solvent, need of transition-metal catalysts, and amount of waste solvents. Due to the medicinal importance of indole and the need for green methods of drug synthesis, this review highlights the latest green synthetic methods leading to the formation of indole-containing compounds focusing on the past 4 years with typical examples. This review is divided into two sections: green solvents and green techniques that lead to the synthesis of indole-derived scaffolds.

Engaging Isatins in Multicomponent Reactions (MCRs) - Easy Access to Structural Diversity

Multicomponent reactions (MCRs) are a valuable tool in diversity-oriented synthesis. Its application to privileged structures is gaining relevance in the fields of organic and medicinal chemistry. Isatin, due to its unique reactivity, can undergo different MCRs, affording multiple interesting scaffolds, namely oxindole-derivatives (including spirooxindoles, bis-oxindoles and 3,3-disubstituted oxindoles) and even, under certain conditions, ring-opening reactions occur that leads to other heterocyclic compounds. Over the past few years, new methodologies have been described for the application of this important and easily available starting material in MCRs. In this review, we explore these novelties, displaying them according to the structure of the final products obtained.