Mini-Reviews in Organic Chemistry - Volume 17, Issue 6, 2020

Pyroglutamic acid is one of the privileged asymmetric precursors for the synthesis of a variety of molecules such as Angiotensin-Converting Enzyme (ACE) inhibitors, angiotensin II receptor subtypes (AT-1 receptor antagonists), as well as bioactive natural products. Starting with primary reports in 1980’s, last almost four decades has witnessed a rapid overgrowth of publications using pyroglutamic acid as a preferred asymmetric precursor and these have been well documented. Pyroglutamic acid has two differential carbonyl groups a lactam carbonyl and a carboxylic functionality along with an NH group, and all of these functionalities can be further derivatized/ transformed and in turn opened avenues for the synthesis of variety of molecules. Derived easily from glutamic acid by internal cyclization, pyroglutamic acid offers a cheap and very good source of chirality and has provided an important tool for the synthesis of natural products/intermediates to natural products. Herein, we wish to describe the exploitation of the chemistry of pyroglutamic acid and its derivatives in the asymmetric synthesis of natural products establishing its versatility as a privileged asymmetric precursor.

The flavonoids by their natural properties and their diverse applications are a group of compounds whose study of origin, characteristics and applications has been dedicated to extensive research. For the organic synthesis of chalcones, due to their interest as precursor molecules of different compounds, several pathways have been developed and reported in numerous works. Analyses on the effect of some of these catalysts on chalcone yield (%), with respect to time and reaction temperature are presented here. Given the importance of flavon-3-ols, as compounds of pharmacological interest mainly, new synthesis routes are proposed, in addition to the existing ones. This paper presents the main pathways for the synthesis of chalcones and analyzes their production. New routes for the synthesis of flavon-3-ols that follow the Claisen-Schmidt condensation and the interconversion of melacacidin are proposed.

Pyrazolotriazolopyrimidines are an important class of nitrogen-containing heterocycles that can act as a charismatic target and exhibit diverse pharmacological activities. These compounds have received much attention because they are an attractive scaffold for the preparation of adenosine receptor antagonists. Herein, we focus on an overview of the synthesis of these compounds with the aim of assisting in the discovery of new pyrazolotriazolopyrimidine derivatives.

PABA (p-aminobenzoic acid) is an important substrate for the synthesis of various biological scaffolds. Its pharmacological significance is apparent form the drugs like folic acid and benzocaine, which are used for certain biological disorders. Although, it is not a vitamin but still it is referred as a member of vitamin B. The deficiency of PABA leads to several disorders like erratic white areas of skin, grey hair, fatigue, depression and irritability. Besides its medicinal importance, PABA has been used in the synthesis of various biologically active heterocyclic nuclei like benzimidazoles, azitidinones, thiazolidinones, pyrazoline, etc. This review will describe the applications of PABA in the synthesis of these biologically active nuclei and hence emphasizing its importance as a versatile substrate.

In recent decades, enzymes have been the target of considerable research, development, and innovation. This paper presents an up-to-date overview of the technological application of lipases in the pharmaceutical industry. Lipases have been used in a variety of ways in the pharmaceutical industry, both for obtaining bioactive molecules to overcome limitations in the formulation of medicines and in drug design. This is possible from alternative technologies, such as immobilization and the use of non-aqueous solvents that allow the use of lipases in commercial-scale processes. In addition, other technologies have provided the emergence of differentiated and more specific lipases in order to meet the perspectives of industrial processes. The research indicates that the following years should be promising for the application of lipase in the industrial biocatalysis and in drug design.

The present review has highlighted the chemistry of pyrimido[1,2-a]pyrimidine compounds as one of the most important classes of heterocyclic systems. The main sections include: (1) The synthesis of pyrimido[1,2-a]pyrimidines, (2) reactivity of the substituents attached to the carbon and nitrogen atoms of the ring and (3) biological applications. A discussion demonstrated that the proposed mechanisms of unexpected synthetic routes were intended. The purpose of this review is to provide an overview of the chemistry of pyrimido[1,2-a]pyrimidines to date, in which the compounds should be widely applied in medicinal and pharmaceutical chemistry based on the significant, variable and potent biological results of pyrimidopyrimidine and pyridopyrimidine analogs. This survey will assist scientists in the organic and medicinal chemistry fields to design and develop procedures for the construction of new standard biological compounds.

Due to its inherent advantages such as easy recovery and reuse of the catalysts/ reagents, and environmentally friendly nature, the heterogeneous system has gain popularity in the realm of organic synthesis. In recent years, several chemically or biologically potent molecules are achieved through heterogeneous synthesis strategies. By recalling some of the classical fundamentals of the heterogeneous system in important organic synthesis, this mini-review outlines the recent developments in the applications heterogeneous catalysts and reagents; particularly in the solid phase synthesis, esterification and transesterification reactions to produce biodiesel, and Henry reaction.

Flavonoids are widely distributed in the plant kingdom and possess a variety of biological activities, such as anti-oxidant, anti-inflammatory, and anti-viral activities. Due to the structural diversity and biological activity, flavonoid derivatives isolated from Verbenaceae family have received a lot of attention by the research scholars. In this paper, a total of 150 natural flavonoids isolated from Verbenaceae and their bioactivities were summarized.