Mini-Reviews in Organic Chemistry - Volume 16, Issue 1, 2019

This review presents most of the literature data about synthesis and biological activity of pyridopyridazine derivatives. There are six structural isomers of the bicyclic ring system containing pyridine moiety condensed with pyridazine nucleus. Pyridopyridazine derivatives show antitumor, antibacterial, analgesic and diuretics activities. The derivatives have been identified as the selective phosphodiesterase 5 and phosphodiesterase 4 inhibitors. Pyridopyridazines are novel class of GABA-A receptor benzodiazepine binding site ligands. Some of pyrido[3,2-c]pyridazine derivatives possess molluscicidal activity and can be used as biodegradable agrochemicals. The broad spectrum of biological activity of pyridopyridazine derivatives is the main reason for the preparation of new compounds containing this scaffold.

Hypervalent iodine(III) reagents are well known for the mild and highly selective oxidative chemical transformations, specifically in synthesis of a variety of heterocycles, in a facile and environmentally friendly manner. In past decades, triazole derivatives have gained much attention of the scientific community as some of the products containing triazole moiety contribute towards the development of effective chemotherapeutics. (Diacetoxyiodo)benzene, a hypervalent iodine(III) reagent has proven its significant role in synthesis of 1,2,4-triazoles, in particular, fused derivatives. This review highlights the (Diacetoxyiodo)benzene mediated developments made for the synthesis of fused 1,2,4-triazole derivatives till date. In addition, medicinal perspective of these heterocycles has also been summarized.

Marine natural products have proven to be a rich source of drugs and drug leads. These natural products are secondary metabolites and show biological activity against bacteria, fungi and viruses. Natural products containing thiazole ring occur often in marine sources. They exhibit diverse and remarkable biological activities, including antitumor, antibacterial, anti-inflammatory and cytotoxic activities, to name a few. This review surveys the natural thiazole derivatives that have been isolated from marine microorganisms, with emphasis on biological implications in last three decades.

The present review provides a comprehensive overview of the synthetic methods developed recently for 6H-Indolo[2,3-b]quinoline. The review is classified into the following: 1) inheriting indole skeleton and constructing quinoline ring; 2) inheriting quinoline skeleton and constructing indole ring, and 3) convergent strategies constructing both rings simultaneously or step by step. This review discusses the scope of multifunctional reactivity of indole and quinoline skeleton for constructing the desired indoloquinolines as explored in various research strategies.

In the past three decades, the heterocyclic oxazine cores have been intensely concerned. Oxazine derivatives are promising vital heterocyclic motifs. They are eminent for their synthetic potential and extensive biological properties. Oxazines are versatile intermediates for the synthesis of a variety of heterocycles and bifunctional compounds. Researchers have reported several synthetic approaches for the preparation of oxazines. This review emphasises the recent approaches for the synthesis of oxazine derivatives.

The kinetics and mechanism of the formation of some ylides,1,4 or 1,5-diionic organophosphorus and phosphonate esters have been reviewed. The UV-vis spectrophotometry, stopped-flow and variable-temperature 1H-NMR spectroscopy along with the theoretical calculations were used as investigative techniques.

Background: Cancer is one of the main causes of death worldwide. Contemporary therapies, including chemo- and radiotherapy, are burdened with severe side effects. Thus, there exists an urgent need to develop therapies that would be less devastating to the patient's body. Such novel approaches can be based on the anti-tumorigenic activity of particular compounds or may involve sensitizing cells to chemotherapy and radiotherapy or reducing the side-effects of regular treatment. Objective: Natural-derived compounds are becoming more and more popular in cancer research. Examples of such substances are Ursolic Acid (UA) and Oleanolic Acid (OA), plant-derived pentacyclic triterpenoids which possess numerous beneficial properties, including anti-tumorigenic activity. Results: In recent years, ursolic and oleanolic acids have been demonstrated to exert a range of anticancer effects on various types of tumors. These compounds inhibit the viability and proliferation of cancer cells, prevent their migration and metastasis and induce their apoptosis. Both in vitro and in vivo studies indicate that UA and OA are promising anti-cancer agents that can prevent carcinogenesis at each step. Furthermore, cancers at all stages are susceptible to the activity of these compounds. Neoplasms that are formed in the gastrointestinal tract, i.e. gastric, colorectal, pancreatic, and liver cancers, are among the most common and most lethal malignancies. Their localization in the digestive system, however, facilitates the action of orally-administered (potential) anti-cancer agents, making chemopreventive drugs more accessible. Conclusion: In this paper, the anti-tumorigenic effect of ursolic and oleanolic acids on gastric, colon, pancreatic, and liver cancers, as well as the mechanisms underlying this process, are presented.

Fullerenes, especially C60, exhibit great potential applications in biology field, due to their excellent antibacterial, antiviral, antitumor and other properties. Many water-soluble fullerene derivatives have been designed, synthesized and used as photo-dynamic therapy agents, antiviral agents, bioimaging agents, drug carriers and so on. This review focuses on the usage of water-soluble fullerene derivatives in biomedical field in recent years. The first half gives the preparation of water-soluble fullerene derivatives themselves with covalent bonds and non-covalent bonds. In the second half, myriad applications of water-soluble fullerene derivatives in biomedical field are introduced.