Current Organic Chemistry - Volume 27, Issue 18, 2023

1,4-dihydropyridine is a versatile class of compounds with multiple biological activities, thus holding significant pharmacological potential. Recent studies have provided evidence concerning the anticancer, antimicrobial, and anti-inflammatory properties of 1,4-dihydropyridines, as well as their potential in Alzheimer's disease treatment. Therefore, this class of compounds is a promising candidate in studies of drug development and drug discovery. The major derivatives of 1,4-dihydropyridine can be synthesized through one-pot synthesis in many different ways, varying the solvents, catalysts, and experimental conditions. Due to the compound's remarkable potential and ease of production, in this review we aimed to present the biological activities and synthesis methodologies of the main 1,4-dihydropyridine derivatives reported by scientific literature over the past decade.

Aromatic azo compounds are 128;œderivatives of diazene/diimide128;, wherein the two hydrogens are substituted by phenyl groups. Azo compounds are very important universal scaffolds that show multiple applications in many areas of science, mainly chemical industries, where they are used in the synthesis of organic dyes, pigments, food additives, indicators, etc. They also remarkably exhibit various potential applications in the fields of pharmaceuticals, electronics, optics, etc., because of their fascinating photophysical properties. Moreover, several azo compounds have been strongly utilized as chemosensors, diagnostic probes, radical initiators, nanotubes, and building blocks of various polymers as well as natural products. This interesting and immense importance of the azo compounds has attracted the attention of researchers to establish novel synthetic routes to synthesize these important scaffolds. In organic chemistry, azo compounds can be synthesized by various methods utilizing coupling reactions with the aid of a catalyst or sometimes in the absence of it. The main purpose of writing this review was to provide a summary of the synthesis of both symmetric and asymmetric azobenzenes via various traditional and recently developed oxidative azo-coupling reactions.

Calix[n]arene is an attractive host for molecular recognition due to its accessibility through the hollow cavity and shallow bowl shape and has been used as a receptor over the last 30 years. Calix[n]arene has a small cavity, so designing a flexible molecule to recognize nano to large biomolecules is a challenging goal in host-guest chemistry. Dimeric calix[n]arene is formed by linking two calix[n]arene sub-units to each other. Their considerable structural features and relative diversity of modifying the upper or lower rim represent outstanding and greatly adaptive structures for designing bulky and complex building blocks adequate for self-assembly and molecular recognition. Their ability to form supramolecular structures for a wide range of applications, including the recognition of nanomolecules and large biological molecules, has been extensively studied. This review details the progress of the host-guest chemistry of dimeric calix[n]arenes, emphasizing the synthetic pathways employed for their production and their self-assembly properties. Dimerization of calix[n]arene occurs in two ways (1-through non-covalent bonding such as H-bonding or self-assembly, and 2-through covalent bond formation such as amide bond formation, multi-component reactions and Sonogashira cross-coupling reaction and metathesis reactions). In this work, we focused on dimerization through covalent bond formation, due to having more applications and diverse synthetic applications.

The aim of this study was to obtain the optimum hydrolysis of cottonseed oil via immobilized lipases (Lipases Rhizopus oryzae, SL from Pseudomonas (Burkholderia) cepacia, Amano lipase from Mucor javanica, ANL from Aspergillus niger lipase, TL from Pseudomonas stutzeri, QLM from Alcaligenes sp., Triacylglycerol lipase (EC 3.1.1.3), PL from Alcaligenes sp., AL from lysosomal acid lipase, Candida antarctica (CA), and Candida cylindrea (CC)) on hydrolysed polyvinyl alcohol (PVA) gel pellets.The production of free fatty acids by the hydrolysis of triglycerides from several sources is an important component in the economic exploitation of naturally produced renewable raw materials.Herein, various lipases, including Rhizopus oryzea, SL, Amano lipase from Mucor javanica, ANL, TL, QLM, EC, PL, AL, CA, and CC were screened for optimum hydrolysis of cottonseed oil. Following the selection of lipase for hydrolysis of cottonseed oil, transparent PVA gel was synthesized by physical gelation method employing Dimethyl sulfoxide and a water system. In the last step, immobilization of selected lipase i.e. Amano lipase for cotton seed oil was carried out at 4oC for one hour. After successful synthesis and immobilization, the PVA gel was characterized by FTIR and SEM analysis. Finally, factorial design was employed for optimization of experimental variables such as pH, time and amount of cotton seed oil hydrolysis by lipase immobilized PVA.The obtained results indicated that lipase Amano was found better with higher free fatty acids (FFA) yields (with 98.38%) in 5 hours using 3 g of cottonseed oil, suggesting that PVA immobilized Amano lipase is an efficient catalyst to hydrolyze the cottonseed oil.The overall study indicated that hydrolysed PVA gel is an effective biocompatible solid support for immobilization of lipases to obtain higher FFA from cottonseed oil following hydrolysis reaction.