Mini-Reviews in Organic Chemistry - Volume 18, Issue 8, 2021

Cinnamic acid and cinnamaldehyde may be obtained from renewable plant bio-mass, Cinnamon plants; therefore these compounds should be considered as bio-based platform chemicals for the synthesis of novel substances. This review describes recent achievements in organic synthesis based on transformations of cinnamaldehyde, cinnamic acid and its derivatives, focusing, mainly, on the preparation of biologically active compounds. Reactions of these cinnamic derivatives may proceed both onto carbon-carbon double bond and carbonyl group that allows obtaining a wide variety of organic compounds having high synthetic importance and different practically valuable properties, including biological activity.

Pyrimidobenzothiazoles and its derivatives are important structural scaffolds in the field of synthetic organic chemistry and medicinal chemistry. The review is focused on one pot multicomponent approaches for generating pyrimidobenzothiazoles and its derivatives along with their interesting biological profile over the last ten years. Several eco-benign and cost effective approaches such as nano catalyst, ionic liquid, metal, solid acid, catalyst free, solvent free, etc. for its synthesis have been discussed in this review. Different synthetic strategies of pyrimidobenzothiazole derivatives have been compiled and discussed using 2-aminobenzothiazole, 1,3 diketones, substituted aldehydes, alkynoic acid, bis-methyl thiomethylene malononitrile, Baylis Hillman acetates, etc.

Covalent Organic Frameworks (COFs) are covalently bonded polymers that are synthesised applying a bottom-up approach using molecular building units that have pre-designed geometry. COFs are crystalline and have control over the position of building units in two and three dimensions, due to which highly regular, rigid, and porous structures can be developed for tuning chemical and physical properties of the network. The present mini-review provides comprehensive overviews of the applications of the COFs in gas storage and water harvesting.

A classic reductive amidation/amination (C-N bond formation) approach for DNJ synthesis has been widely practiced due to the availability of low-cost reagents. The key steps for this synthetic route are Swern oxidation, reductive amidation/amination, and debenzylation. A lot of attention has been given to the optimization of these key intermediates apart from debenzylation. This review aims to describe the deprotection advances employing efficient, systematic, and practical protocols for sample preparation and separation by using Pd(OH)2/C, Li, BCl3 and Pd/C as catalysts. The impact of varying reaction parameters such as solvents, acids and temperature for deprotection was emphasized for optimal DNJ synthesis.

Food safety arising from exogenous contaminants has become a global concern. The development of simple, rapid and sensitive methods for effective detection and management of trace levels of exogenous contaminants has emerged as a hotspot, as well as the important priorities in food industry. Nanozymes that are defined as the emerging enzyme-like nanomaterials with robust catalytic activity, simple preparation, high stability, and low cost have been widely used in the construction of biosensors for the detection of hazardous contaminants in foods, greatly accelerating the advancement of food safety assay. In this review, we comprehensively summarize the recent advances of nanozyme-based biosensors, such as colorimetric, electrochemical, photo-electrochemical and surface- enhanced Raman spectroscopy-based sensors, over the past five years for the detection of various exogenous contaminants including mycotoxins, heavy metals, pesticides, antibiotics, pathogens and microcystins in foods. Beyond a highlight of the advantages and limitations in real-world application, we critically propose the current challenges and future trends of these biosensors for exogenous contaminant detection in foods to guarantee their quality and safety.

Benzimidazole and its derivatives are privileged heterocyclic motifs and important building blocks for the development of the biologically active compound. However, several research reports are produced in a short period of time due to the rapid production of new drugs having a benzimidazole nucleus. In order to understand the current status of the benzimidazole nucleus in medicinal chemistry, it is therefore important to combine the latest knowledge with earlier information. Hence, synthetic organic chemists concentrated on inventing an effective green methodology for synthesizing benzimidazole derivatives. In addition to this, non-degradable chemical compounds cause the ecosystem to become fragile, damaged, or irritated as contaminants pose a danger to the environment. However, conventional methods of synthesis need longer heating time, with complicated and tedious apparatus set up, which results in high cost and pollution in contrast to greener methods which are inexpensive. In the present review, we have attempted to shed light on various synthetic strategies leading to the synthesis of different benzimidazole derivatives through the direct condensation reaction between ophenylenediamine and aromatic aldehydes using green chemistry approaches such as mechanochemistry, ultrasound irradiation, microwave irradiation, environmentally benign solvents/catalysts, reactant immobilized on a solid support, and blue light irradiation.

Heterocyclic compounds are important because they have almost all types of pharmacological properties. Due to these properties of heterocyclic compounds, they attracted the researchers for the development of more effective newer drug molecules. In this review, we are focused on benzothiazole and its derivatives, which are used for the synthesis of various biologically active molecules. Benzothiazole derivatives have possessed various pharmacological activities like antimicrobial, antiinflammatory, analgesic, anticonvulsant, antiviral, anthelmintic, antioxidant, anticancer, and other anticipated activities. Hence, structural alterations have resulted in different benzothiazole derivatives that illustrated a wide variety of pharmacological activities.

Schiff base or imine or azomethine is one of the most important organic compounds that has been reported to play a significant role in various biological processes. The group is a part of natural or non-natural compounds and is involved as important precursors, as diversified agents and as intermediates, in the synthesis of biologically active agents. The review outlines the detailed design strategy, synthesis and structure-activity relationship studies of different Schiff bases for various biological activities. We have tried to outline the key points of various researchers with respect to biological activities. The results of different studies demonstrate Schiff bases as a linker in many synthetic compounds displaying a broad range of activities. We believe that the present review will provide comprehensive knowledge on the medicinal importance of Schiff bases and serve as important literature in designing the synthesis of novel molecules containing Schiff base as pharmacophore or biologically active moiety.

Triazines and their oxo derivatives are a representative class of heterocyclic compounds which have attracted great attention in organic synthesis and medicinal chemistry as they have been associated with a broad range of pharmacological activities. 1,2,4-Triazines and their oxo derivatives exhibit a broad range of biological activities, including antimicrobial, antifungal, anticancer, antiinflammatory, besides having importance in the dyes and pesticides field. This review presents the different methods of the synthesis of triazine/one derivatives. Also, this literature surveys the different effects of these compounds in pharmaceuticals.

This review deals with the synthetic methods, chemical reactions, and applications of triazolopyrimidine derivatives. The synthetic methods and chemical reactions are subdivided into groups according to the junction between triazole and pyrimidine moieties for instance [1,2,4]triazolo[1,5- a]pyrimidine, [1,2,4]triazolo[1,5-c]pyrimidine, [1,2,3]triazolo[1,5-a]pyrimidine, [1,2,3]triazolo[1,5- c]pyrimidine, [1,2,4]triazolo[4,3-c]pyrimidine, and [1,2,4]triazolo[4,3-a]pyrimidine. Pharmacological activity of triazolopyrimidins is also reported.