Comprehensive Review on Synthetic Approaches and Biological Activities of 1,3,4-Oxadiazole

Among the large variety of nitrogen and oxygen heterocycles, 1,3,4-oxadiazole, the scaffold, has attracted considerable attention owing to its ability to showing an extensive range of pharmacological actions. Therefore, significant efforts of organic chemists have been directed towards the construction of new drug candidates containing 1,3,4-oxadiazole subunits connected to a known pharmaceutical or a potential pharmacophore. This digest highlights recent publications on the various synthesis techniques of 1,3,4-oxadiazole and related compounds over the previous ten years (2011–2021). The purpose of this review is to learn about several ways for synthesizing oxadiazole. These heterocyclics are formed mainly by the cyclization reactions of various reactants under diverse circumstances. According to the literature investigations, they were given a high priority for their pharmacological significance, such as anticonvulsant, anticancer, antioxidant, anti-inflammatory, antibacterial, antidiabetic, etc.

Total Synthesis of the Natural Chalcone Lophirone E, Synthetic Studies toward Benzofuran and Indole-Based Analogues, and Investigation of Anti-Leishmanial Activity

The potential of natural and synthetic chalcones as therapeutic leads against different pathological conditions has been investigated for several years, and this class of compounds emerged as a privileged chemotype due to its interesting anti-inflammatory, antimicrobial, antiviral, and anticancer properties. The objective of our study was to contribute to the investigation of this class of natural products as anti-leishmanial agents. We aimed at investigating the structure–activity relationships of the natural chalcone lophirone E, characterized by the presence of benzofuran B-ring, and analogues on anti-leishmania activity. Here we describe an effective synthetic strategy for the preparation of the natural chalcone lophirone E and its application to the synthesis of a small set of chalcones bearing different substitution patterns at both the A and heterocyclic B rings. The resulting compounds were investigated for their activity against Leishmania infantum promastigotes disclosing derivatives 1 and 28a,b as those endowed with the most interesting activities (IC50 = 15.3, 27.2, 15.9 μM, respectively). The synthetic approaches here described and the early SAR investigations highlighted the potential of this class of compounds as antiparasitic hits, making this study worthy of further investigation.

Dibenzo[d,d′]benzo[2,1-b:3,4-b′]difurans with extended π-conjugated chains: synthetic approaches and properties

Ru-Catalysed reaction of 3,8-di(hexyn-1-yl)dibenzo[d,d']benzo[2,1-b,3,4-b′]difuran [3,8-di(hexyn-1-yl)-DBBDF] with 2 equivalents of methyl (E)-penta-2,4-dienoate produces 3,8-bis[(1E,3E,5E)-2-butyl-6-methoxycarbonylhexa-1,3,5-trien-1-yl]-DBBDF (9a).

4.1 Strain-Promoted Azide–Alkyne Cycloaddition (SPAAC): Background, Substrate Preparation, and Reactivity

This chapter discusses the creative synthetic approaches to azides and cycloalkynes, provides the rationale for controlling SPAAC reactivity through tuning cycloalkyne and azide backbone modifications, and highlights research on nitrone cycloadditions with cycloalkynes. This synthetic and knowledge toolset will help in the design of better cycloalkynes and their partners to answer challenging research questions and aid the development of new applications.

Covalent nanosynthesis of fluorene-based macrocycles and organic nanogrids

This paper presents an overview of synthetic approaches for fluorene-based cyclic compounds by examining four different connection models of fluorenes, involving 2,7-, 3,6-, 9,9-, and 2,9-linked patterns.

Double hydrophilic copolymers – synthetic approaches, architectural variety, and current application fields

Double hydrophilic copolymers consist of two chemically different but water-soluble segments. We present synthetic approaches and both established as well as emerging applications such as photocatalysis or sensing.

Trinuclear ReFePt clusters with a μ3-phenylvinylidene ligand: synthetic approaches, rearrangement of vinylidene, and redox-induced transformations

Approaches to the synthesis of trinuclear ReFePt clusters, their behaviour in solution and pathways of their redox-induced reactions are studied.

Difluorocarbene Enabled to Access 1,3-oxazin-6-ones from Enamides

1,3-Oxazin-6-ones as an important structural scaffold are widely existing in many bioactive or therapeutic agents. The development of straightforward synthetic approaches to access 1,3-oxazin-6-one is highly desirable for studying their...