A new and efficient synthesis of 1,3,4-oxadiazole derivatives using TBTU

Design, synthesis, in vitro and in silico evaluation of novel substituted 1,2,4-triazole analogues as dual human VEGFR-2 and TB-InhA inhibitors

Cancer is a leading cause of death globally and has been associated with Mycobacterium tuberculosis (Mtb). The angiogenesis-related VEGFR-2 is a common target between cancer and Mtb. Here, we aimed to synthesize and validate potent dual human VEGFR-2 inhibitors as anticancer and anti-mycobacterial agents. Two series of 1,2,4-triazole-based compounds (6a-l and 11a-e) were designed and synthesized through a molecular hybridization approach. Activities of all synthesized compounds were evaluated against human VEGFR-2 in addition to drug-sensitive, multidrug-resistant and extensive-drug resistant Mtb. Compounds 6a, 6c, 6e, 6f, 6h, 6l, 11a, 11d and 11e showed promising inhibitory effect on VEGFR-2 (IC50 = 0.15 - 0.39 µM), anti-proliferative activities against cancerous cells and low cytotoxicity against normal cells. The most potent compounds (6e and 11a) increased apoptosis percentage. Additionally, compounds 6h, 6i, 6l and 11c showed the highest activities against all Mtb strains, and thus were evaluated against enoyl-acyl carrier protein reductase (InhA) which is essential for Mtb cell wall synthesis. Interestingly, the compounds showed excellent InhA inhibition activities with IC50 range of 1.3 - 4.7 µM. Docking study revealed high binding affinities toward targeted enzymes; human VEGFR-2 and Mtb InhA. In conclusion, 1,2,4-triazole analogues are suggested as potent anticancer and antimycobacterial agents via inhibition of human VEGFR-2 and Mtb InhA.

Copper-Catalyzed One-Pot Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles from Arylacetic Acids and Hydrazides via Dual Oxidation

A simple and efficient protocol has been developed to access symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles from arylacetic acids and hydrazides via copper-catalyzed dual oxidation under an oxygen atmosphere. Oxidative decarboxylation of arylacetic acids and oxidative functionalization of the imine C-H bond are the key steps. This is the first example of the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles through dual oxidation in one-pot. Avoidance of the expensive ligand and high yield of the products are advantageous features of the developed method.

Recent updates on Synthetic Strategies and Biological Potential of 1,3,4-oxadiazole: Review

Abstract:

Among the large variety of nitrogen and oxygen-containing heterocycles, 1,3,4-oxadiazole, the scaffold, has attracted considerable attention owing to its ability to show an extensive range of pharmacological actions. According to literature investigations, prepared 1,3,4-oxadiazole and its derivative are pharmacologically significant and consist of a variety of activities, such as anticonvulsant, anticancer, antioxidant, anti-inflammatory, antibacterial, antidiabetic, etc. These heterocyclics are formed mainly by the cyclization reactions of various reactants under diverse reaction circumstances. Therefore, significant efforts of organic chemists have been directed towards the synthesis of new drug candidates containing 1,3,4-oxadiazole subunits connected to an established potential pharmacophore to improve the efficacy and potency. This article aims to highlight 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 help researchers by summarizing several synthetic strategies for synthesizing oxadiazole.

DEAD-Mediated Oxidative Ugi/Aza-Wittig Reaction for the Synthesis of 5-(1,2,3,4-Tetrahydroisoquinolin-1-yl)-1,3,4-oxadi­­azoles Starting from (N-Isocyanimine)triphenylphosphorane

A one-pot protocol for the synthesis of 5-(1,2,3,4-tetra­hydroisoquinolin-1-yl)-1,3,4-oxadiazoles via DEAD-mediated oxidative Ugi/aza-Wittig reaction has been developed. The reaction of (N-iso­cyanimine)triphenylphosphorane, carboxylic acids, and N-aryl-1,2,3,4-tetrahydroisoquinolines produced polysubstituted 5-(1,2,3,4-tetra­hydroisoquinolin-1-yl)-1,3,4-oxadiazoles directly in good yields in the presence of DEAD as an oxidant.

Carbodiimide-based synthesis of N-heterocycles: moving from two classical reactive sites to chemical bond breaking/forming reaction

Carbodiimides are a unique class of heterocumulene compounds that display distinctive chemical properties. The rich chemistry of carbodiimides has drawn increasing attention from chemists in recent years and has made them exceedingly useful compounds in modern organic chemistry, especially in the synthesis of N-heterocycles. This review has outlined the extensive application of carbodiimides in the synthesis of N-heterocycles from the 1980s to today. A wide range of reactions for the synthesis of various types of N-heterocyclic systems (three-, four-, five-, six-, seven-, larger-membered and fused heterocycles) have been developed on the basis of carbodiimides and their derivatives.

A Useful Synthesis of 2-Acylamino-1,3,4-oxadiazoles from Acylthiosemicarbazides Using Potassium Iodate and the Discovery of New Antibacterial Compounds

A useful method for the synthesis of 2-acylamino-1,3,4-oxadiazoles was developed. By using potassium iodate as an oxidant in water at 60 °C, a wide range of 2-acylamino-1,3,4-oxadiazoles were afforded in moderate to excellent yields within two hours. This method could provide a facile shortcut to generate a series of 2-acylamino-1,3,4-oxadiazoles in medicinal chemistry. Interestingly, some highly potent antibiotic compounds were found through this synthetic method, and some of them displayed a significant improvement in activity compared with the corresponding 1,4-diacylthiosemicarbazides. Compound 2n was the most active against Staphylococcus aureus with MIC (minimum inhibitory concentration) of 1.56 mg/mL, and compounds 2m and 2q were the most active against Bacillus subtilis with MIC of 0.78 mg/mL. The preliminary cytotoxic activities of the most potent compounds 2m, 2n, and 2q against the androgen-independent (PC-3) prostate cancer cell line were more than 30 μM (IC₅₀ > 30 μM).

Efficient synthesis of novel conjugated 1,3,4-oxadiazole–peptides

In this study, we developed an efficient approach for the synthesis of 2-amino-1,3,4-oxadiazoles that are bioisosteres of the amide functional group. The synthesized oxadiazoles were conjugated to octa- and nonapeptides through the C- or N-terminus as precursors of leuprolide acetate. The synthesized compounds are peptidomimetics of leuprolide acetate.

Novel 1,3,4-oxadiazole motifs bearing a quinoline nucleus: synthesis, characterization and biological evaluation of their antimicrobial, antitubercular, antimalarial and cytotoxic activities

Quinoline–oxadiazole hybrids: a new class of antimicrobial, antitubercular and antimalarial compounds.

Synthesis of functionalized chromones through sequential reactions in aqueous media

An efficient sequential four-component reaction of chromone carbaldehydes, Meldrum's acid, 4-hydroxyl coumarin or 6-methyl-4-hydroxyl-pyrone and primary alcohols is reported which leads to 5a-i in aqueous media. Replacing the primary alcohol with isopropyl alcohol and tert-butyl alcohol results in different products 10 and 11. The environmentally friendly features, good to high yields and easy work-up are advantages of this approach.