Mini-Reviews in Organic Chemistry - Volume 17, Issue 4, 2020

The β-hydroxy sulfides are an important class of organosulfur compounds that have a key role in the synthesis of bioactive compounds containing biological and natural products. The thiolysis of epoxides is the most common and best route for the synthesis of β-hydroxy sulfides. During the last decade, the applications of a diverse range of catalysts and promoter agents in green and organic mediums as well as under solvent-free conditions for the regioselective ring-opening reactions of epoxides with thiols in order to synthesize β-hydroxy sulfides have been studied by various research groups. This review is focused on the important achievements reported in the literature for the thiolysis of epoxides.

In this review, works of various researchers working on the synthesis of indazole and their related compound are cited. The review comprises of methodologies for the synthesis of 1H and 2H indazole derivatives, along with some pharmacological activities. In this review, research papers published in various peer-reviewed journals between the year 2000 and year 2017 are enlisted in alphabetical order.

Oxidation reactions have emerged as one of the most versatile tools in organic chemistry. Various onium salts such as ammonium, phosphonium, arsonium, bismuthonium, tellurium have been used as phase transfer catalysts in many oxidation reactions. Certainly, considerable catalysts have been widely used in Phase-Transfer Catalysis (PTC). This review focuses on the application of PTC in various oxidation reaction. Furthermore, PTC also conforms to the concept of “Green Chemistry”. • Oxidation has become one of the most widely used tools in organic chemistry and phase transfer catalysts has been widely used in oxidation. • The application of phase transfer catalysts in oxidation reaction will be summarized. • Phase transfer catalysts have important application in various oxidation reaction.

A comprehensive review of recent existing methods of epoxidation of vegetable oils, unsaturated fatty acids and alkyl esters of unsaturated fatty acids has been presented. The importance of epoxidized vegetable oils and their applications in the production of polyols and polyurethanes was discussed. Interests of researchers have been mainly focused on the development of advantageous technological parameters of vegetable oils epoxidation. The epoxidations with peracetic acid or performic acid generated in situ were mainly performed in the presence of strongly acidic catalysts. The influence of process variables such as temperature, stirring speed, the molar ratio of carboxylic acid and hydrogen peroxide to the amount of ethylenic unsaturation, amount of catalyst and reaction time on the course of epoxidation has been investigated.

Sulfoxides are key scaffolds in the synthesis of pharmaceutically active molecules. A large number of sulfoxides are indispensable ingredients in the structure of most antibiotics, biological and natural products such as Modafinil, Adrafinil, CRL-40,941 or fladrafinil, Fipronil, Oxydemetonmethyl, Omeprazole, Pantoprazole, Lansoprazole and Rabeprazole. The oxidation of sulfides is the most common and efficient strategy for the preparation of sulfoxides. Recently, many protocols based on using transition metals have been reported for the oxidation of sulfides to the sulfoxides. In this paper, we summarized a nice category of the reported protocols in the literature for the oxidation of sulfides to sulfoxides.

Dicationic ionic liquids are an emerging group of Ionic Liquids (ILs) that are currently receiving much attention as green reaction media and catalysts. Because of a great number of possible combinations of cations and anions, the physical and chemical properties of dicationic ionic liquids are more tunable and broader than monocationic ILs. Therefore, their unique properties have made them the target of many applied and fundamental researches. Actually, dicationic ionic liquids are more effective and rather fascinating than traditional monocationic ILs. So, due to greater versatility and diversity, their applications in organic synthesis have been extensively grown. In this review, we have focused on the synthesis, characterization and applications of dicationic ionic liquids, especially, in organic synthesis.

1,5-Benzodiazepines are considered some of the most vital classes of heterocyclic compounds due to their amazing biological and varied pharmacological activities. They are regarded as privileged structures and therefore have been striking synthetic targets for organic and medicinal chemists over the last decade. This results in the exploration of various silica supported catalysts, Lewis acids, organoacids, magnetic nanoparticles and other miscellaneous catalysts that have been investigated till date for an efficient and green synthesis of 1,5-benzodiazepine and its derivatives. The current review article primarily covers the one-pot green chemical synthesis of 1,5- benzodiazepines using various novel catalysts. The main motive of this review is the assessment of the literature on various catalysts along with their yield, reaction condition, and mechanism of action. In the end, the entire catalysts are structured systematically into various Lewis acids, Bronsted organoacids, supported catalysts, nanocatalysts, and miscellaneous catalysts and are presented in the form of tables for quick ‘at a glance’ study of catalysts, their reaction condition, time taken, etc.