Mini-Reviews in Organic Chemistry - Volume 17, Issue 2, 2020

Surfactant Aided Lewis Acids (LASCs) make an appearance as one of the efficient and substantial heterogeneous catalysts. Recently, various LASCs have been used as green and heterogeneous catalysts in organic synthesis due to their high water stability, recyclability, cost-effective nature and their ability to create stable colloidal dispersions. In the present review, we have discussed a variety of carbon-carbon bond forming, ring opening, addition and multi-component reactions for the synthesis of various biologically important heterocyclic compounds that have been successfully catalyzed by LASCs. In most cases, the catalytic activity of LASCs was found to be better in water in comparison to other organic solvents, which attracts special attention towards the present review.

Conventional hydrocracking catalysts generally to retain their active form. However, sulfuration may cause sulfur dioxide emissions, corrosion, and sulfur residue in products, as plant oils become freed of sulfur compounds. The high price of this noble metal also limits industrial applications. Therefore, non-sulfided catalysts can eliminate the presulfurization step and mitigate sulfiderelated threats on both the environment and human health. The purpose of this paper is to review current developments in the species and application of inexpensive non-sulfided catalysts for the hydrocracking of non-edible Jatropha curcas L. oil. This mini-review predominantly concerns Nibased catalysts supported by rare-earth metals or heteropoly acid. These catalysts were used in the hydrotreating or hydrocracking of Jatropha oil to produce green diesel.

Benzothiazine is a heterocyclic compound consisting of a benzene ring attached to the 6- membered thiazine ring. The benzothiazines constitute the group of heterocyclic compounds as they have found a variety of industrial uses and show promise as herbicides. Besides this, benzothiazines play an important role in the field of drug discovery as they have the potential to act as drug candidates for the treatment of a large number of diseases including, cancer, vasorelaxant, diabetic, hypertension, mycotic infection and microbial infection. The presence of nitrogen-sulphur axis and similarity in the structure with phenothiazine drugs help the benzothiazines to act as drugs for the treatment of a number of diseases. Herein, we represent different synthetic strategies for the simple and multi-component synthesis of benzothiazine heterocyclic derivatives. The strategies mostly involve the use of 2-aminothiophenol, 1, 3-dicarbonyl compounds or α-haloketones. In almost all the strategies, the potential yields have been obtained.

Seriphidium plants were reported to be utilized by local communities to cure their ailments in the form of paste, tincture, tea, nutraceuticals due to their medicinal properties. Most of the species are used as food, forage and ornamentals, etc. Due to the significant properties of the Seriphidium plants, the present article was designed to compile the data of major aspects and chemical constituents of genus Seriphidium responsible for their significant uses. This review article comprehensively covers the biological potential of different plants with their secondary metabolites and describes an overview of the biological activities of the different species belonging to genus Seriphidium. The main secondary metabolites isolated from different species of the genus Seriphidium are triterpenoid, sesquiterpenes, flavonoids, coumarins, chromones, anthraquinones, polyphenols and their glycosides, phenolic derivatives, balchanins, costunolides, Vulgarin, pyridine derivatives, ceramides, biphenyls, isoflavones. All these compounds are used in the drug industry.

In this review, we present the recent advances in unusual novel ketosynthases catalyzing the non-decarboxylative Claisen condensations, including CsyB, MxnB/CorB, Ppys and StlD. The differences are summarized between these non-decarboxylative ketosynthases and the typical decarboxylative ketosynthases. Furthermore, the detailed enzymatic characteristics, structural basis, and catalytic mechanismof these novel ketosynthasesare described. Finally, the prospect of these kind of ketosynthases is discussed.

The hydantoin moiety is found in several bioactive compounds with important pharmacological properties such as antimicrobial, antifungal, anti-androgens, anticancer and the historical action anticonvulsant. Because of these reasons, the synthesis of these compounds and their derivatives is important to review considering the philosophy of the green chemistry. In this review, we present the actual importance in the green synthesis of hydantoins and their derivatives using green methods, such as microwave and ultrasound irradiation, ionic liquids, solid-phase and solvent-free synthesis. Finally, several green protocols reported have been discussed.

Flavonoids are considered as a significant class of compounds among the natural products, exhibiting a variety of structural skeletons as well as multidirectional biological potentials. In structural elucidations of natural products, Nuclear Magnetic Resonance (NMR) spectroscopy has been playing a vital role; the technique is one of the sharpest tools in the hands of natural products chemists. The present resume deals with hard-core applications of such spectral technique, particularly in structural elucidation of flavonoids; different NMR techniques including 1H-NMR, 13C-NMR, and 2D-NMR [viz. 1H-1H COSY, COLOC, HMBC, HMQC] are described in detail.

In the last few decades, pyrazole chemistry has attracted chemists’ and biologists’ attention mainly due to the discovery of the interesting properties of a great number of pyrazole derivatives. The resulting proliferation of research literature reflects the enormous biological potential of pyrazole derivatives as antitumor, anti-inflammatory, anti-HIV and antimicrobial agents. This review focuses on research concerning the antimicrobial activity of pyrazole derivatives conducted from 2010-2018, and is intended to assist in the development of a new generation of antimicrobial drugs.