Current Topics in Medicinal Chemistry - Volume 25, Issue 5, 2025

Synthetic routes of chromene are an area of thrust research due to its wide application as pigments, agrochemicals, cosmetics, and an important nucleus scaffold for various pharmacologically active drugs. The chromene nucleus is an important moiety for the discovery of new drug candidates owing to its broad range of pharmacological actions like antitumor, anti-inflammatory, antiviral, and many others. However, traditional synthesis techniques frequently use unsafe reagents and produce hazardous waste, presenting environmental issues. The eco-friendly production of chromene derivatives utilizes sustainable raw materials, non-toxic catalysts, and gentle reaction conditions to reduce ecological consequences. Innovative methods like microwave irradiation, ultrasound synthesis, the use of environmentally friendly solvents, a catalyst-based approach with minimal environmental impact, and mechanochemistry-mediated synthesis are implemented. These approaches provide benefits in scalability, cost-effectiveness, and ease of purification. This review compiles and presents various recently reported green synthetic strategies of chromene and its derivatives and gives the reader a clear idea of the detailed and critical aspects of various synthetic protocols described.

Pyrrole derivatives are known as building blocks for the synthesis of biological compounds and pharmaceutical drugs. Several processes were employed to synthesize pyrroles, including Hantzsch, Paal-Knorr, and cycloaddition of dicarbonyl compounds reaction. Using catalysts like nanoparticles, metal salts, and heterogeneous ones was necessary to obtain the targeted pyrrole structure. Also, to afford more active pyrrole compounds, heterocyclic molecules such as imidazole or other rings were used in the synthesis as amines. This review presents heterogeneous catalysts since 2010 for the green synthesis of bioactive pyrroles in a one-pot multi-component reaction.

Additionally, each synthetic method included a demonstration of the suggested mechanisms. Diakylacetylenedicarboxylate, dicarbonyl group, amines, furans, and acetylene group are consolidated to yield biological pyrroles through the heterogeneous catalysts. Finally, various pyrrole-performed activities were displayed, such as antibacterial, anti-inflammatory, analgesic, and other significant activities.

Bicyclic quinazolinone constitutes an important class of organic framework enveloping numerous biological properties which enthused organic and medicinal chemists to explore green synthetic strategies for the construction of quinazolinone hybrids with significantly improved pharmacodynamics and pharmacokinetic profiles. In this perspective, the present review summarizes the most recent green synthetic strategies, biological properties, structure-activity relationship, and molecular docking studies of the 4-quinazolinone-based scaffold. This review provides deeper insight into the hit-to-lead synthesis of quinazolinone derivatives in the development of clinically important therapeutic candidates.

Cancer continues to be a major global health challenge, driving the need for the discovery of novel therapeutic agents. Among these, heterocyclic phytochemicals have gained significant attention for their potential as anticancer agents. This review offers a detailed analysis of various classes of heterocyclic compounds with proven anticancer properties, shedding light on their mechanisms of action. The study draws from a diverse array of natural product sources, detailing the chemical structures and bioactivities of these compounds. Key heterocyclic classes such as alkaloids, flavonoids, coumarins, and terpenoids are emphasized due to their potent anticancer effects. Heterocyclic phytochemicals exhibit diverse anticancer mechanisms, including the modulation of cellular pathways like apoptosis, angiogenesis, and cell cycle progression. The combination of heterocyclic phytochemicals with conventional cancer therapies has shown promising synergistic effects, enhanced treatment efficacy and reducing side effects. The review systematically evaluates both preclinical and clinical studies, revealing the efficacy, safety profiles, and pharmacokinetics of selected heterocyclic compounds. The promising outcomes highlighted in this review underscore the critical need for ongoing research to fully realize the therapeutic potential of heterocyclic phytochemicals in cancer treatment.

There are many different applications of heterocyclic molecules in pharmaceutical and materials science, which make them an important family of compounds. Among these heterocyclic compounds, nitrogen-containing heterocyclic (N-heterocyclic) compounds have attracted a lot of interest among researchers due to their various applications across a wide variety of fields. Many studies have been performed over the past few years to study the synthesis of N-heterocycles under different reaction conditions, such as solvent-free, catalytic conditions, reactants immobilized on a solid support, one-pot synthesis, and microwave irradiation. Our research group has demonstrated that microwaves can be utilized for rapid and efficient synthesis of biologically active compounds. In this review, we provide an overview of the microwave-assisted non-catalytic and catalytic preparation of nitrogen-containing heterocycles, mostly polycyclic N-heterocycles, five-membered N-heterocycles, six-membered N-heterocycles, and fused N-heterocycles. In this review, we explore the microwave-assisted preparation of biologically important compounds, such as pyrimidines, thiazoles, imines, tetrazoles, steroidal derivatives, quinolines, indolizine, triazoles, beta-lactams, pyrroles, and quinoxalines.

The benzothiazole ring system has been recognised with crucial pharmacophoric features being present among various approved drugs and clinical and pre-clinical candidates. The medicinal importance of this privileged scaffold stimulated the interest of synthetic medicinal/organic chemists for the synthesis of its derivatives due to their diverse biological applications. In most of the reports in the literature, benzothiazoles were synthesized by cyclocondensation of 2-aminothiophenol with either carboxylic acid and its derivatives or aldehydes. However, many of these procedures involve reaction conditions that are not in conformity with sustainable chemistry development. The negative impact of chemicals and their manufacturing processes on the environment, human health, and biodiversity raises safety concerns. On the other hand, the utilization of non-renewable energy sources, use of rare earth metals as catalysts, involvement of costly chemicals, prolonged reaction time at high temperatures, and considerable waste generation diminish the greener impact of these reaction methodologies and make them non-sustainable. In order to avoid such drawbacks of the non-sustainable practices in the synthesis of benzothiazoles, there have been continuous efforts to develop greener methodologies for the construction of this bioactive scaffold. This review aims to delve into the literature reports on the recent advancements in the development of greener methodologies for the synthesis of bioactive benzothiazoles.