Current Organic Synthesis - Volume 20, Issue 6, 2023

Two efficient, scalable routes to bis-1,2,4-oxadiazole have been developed by tandem Staudinger/aza-Wittig reaction from the same starting material diaziglyoxime, isocyanates and triphenylphosphonium in good yields. Background: Two convenient and efficient routes for synthesizing diamino derivatives of bis-1,2,4- oxadiazoles were described. Objective: This study provides a simple protocol for the synthesis of bis-1,2,4-oxadiazoles. Methods: The two procedures were based on a tandem Staudinger/aza-Wittig reaction from the same starting material of diaziglyoxime, isocyanates and triphenylphosphonium. Results: In synthesis method I, diaziglyoxime 1 was treated with various aromatic or aliphatic isocyanates to give diazioxalimides 2 a high yield. Diazioxalimides 2 reacted with Ph3P to produce the iminophosphoranes 4; the reaction was directly heated from room temperature to 115 132;ƒ to get the desired diamino derivatives of bis-1,2,4-oxadiazole 4 in 72-92% yields. In synthesis method II, the same target compounds 4 were synthesized in a one-pot reaction by Ph3P and aromatic or aliphatic isocyanates in toluene for 10 h under 115° in 53-71% yields. Conclusion: The two procedures provide proficient methods of making nitrogen-containing heterocyclic rings. The structures of target compounds 4 were identified by IR, 1HNMR, 13CNMR and HRMS.

Cancer is the second most source of cessation of life globally, with 9.6 million expirations at each stage around the globe. The resistance to the current chemotherapies urges researchers to develop new drugs to be available in the market. Among the wide range of drugs synthesized, heterocyclic compounds play a major role due to the abundance of heterocyclic rings in biological substances. In medicinal chemistry, benzimidazole is an important pharmacophore and a privileged structure. This bicyclic compound is made up of the fusion of a six-membered benzene ring and a five-membered imidazole ring with two nitrogen atoms at 1,3-positions. The benzimidazole ring has a great deal of stability. Many strong acids and alkalis do not affect benzimidazoles. The benzene ring of benzimidazole cleaves only under extreme conditions. Except in certain circumstances, the benzimidazole ring is also quite resistant to reduction. It is the most popular nucleus to study because of its wide range of biological functions. The recently developed methods for preparing benzimidazoles, such as condensation of o-phenylene diamines (OPDs) with aldehydes and many others using a wide range of nano, metal-based catalysts under solventfree conditions, are discussed in detail in the current studies.

Quinoline derivatives are an important class of heterocyclic compounds and possess various applications in synthetic organic chemistry, medicinal chemistry, material chemistry and natural product chemistry. This review article describes the different quinoline derivatives having antimalarial, analgesic, anti-inflammatory, antineoplastic, antibacterial, antifungal, antiviral, anthelmintic, antiprotozoal, cardiovascular, CNS and other useful bioactivities. We have delineated the general synthetic routes for the synthesis of many bioactive quinoline based heterocycles. In addition to this, we have also discussed the crucial synthetic routes as well as their mechanistic paths for the formation of bioactive quinoline derivatives. The study shows that substitution at the 4 and 8- position of quinoline is more crucial for bioactivity as compared to other positions.

Imidazoles have long held a special place in heterocyclic chemistry, and their derivatives have piqued interest in recent years due to their diverse chemistry and pharmacology features. Imidazole is a biologically and pharmaceutically important nitrogen-containing heterocyclic ring. As a result, researchers have been interested in imidazole molecules. For a century and a half, purine, histamine, and other natural compounds all contained the imidazole ring. A number of imidazole drugs have been prepared and marketed for the treatment of various diseases. In view of this, we herein report a detailed account of synthetic procedures for various imidazole drugs.

Derivatives of 1,3,4-oxadiazole are effective in the treatment and cure of a wide range of diseases in medical chemistry, while industrial development has shown that they can be utilised as corrosion inhibitors and light-emitting diodes. The researchers discovered several promising synthetic strategies that created 1,3,4-oxadiazoles in extraordinarily high yields while using environmentally friendly methods. These compounds can potentially be used in a wide range of lifechanging applications. Stable isomeric oxadiazole forms of pleconaril, raltegravir, butalamine, fasiplon, oxolamine, and several other drugs are among the numerous potent and effective pharmaceuticals that are now on the market. Fasiplon, butalamine, raltegravir, and pleconaril treat HIV/AIDS patients. This article has attempted to bring attention to the chemistry and pharmacology of oxadiazole and its derivatives. Oxadiazole derivatives have been used extensively as prospective therapeutic agents in clinical research, and this has become standard practice. The use of biological and in-silico models has enabled scientists to identify more synthetic analogues of cancer prevention, antifungal, and anti-HIV medications. This article provides recent information regarding procedures for synthesizing 1,3,4-oxadiazoles and their biological actions on the body.

Pyrimidines serve as key structural components in chemical frameworks and biological processes. Several pyrimidine analogues have been produced over the years by means of traditional methods that necessitated large amounts of solvents, reagents, and, most importantly, additional time, which has led them to become prohibitive. These procedures are now being replaced with more cost-effective adaptive methodologies that incorporate one-pot synthesis and greener approaches involving various green solvents and catalysts. The current review covers a number of green synthetic techniques, including ultrasound-assisted synthesis, visible light irradiation synthesis, solvent-free synthesis, catalyst-free synthesis, microwave-assisted synthesis, and green catalyst synthesis for the synthesis of pyrimidine derivatives. Accordingly, it integrates different strategies to synthesize heterocyclic pyrimidine analogues in a well-organized manner.