Mild and Efficient Synthesis of 5‐(2,2‐difluoro‐1‐phenyl cyclopropyl)‐N‐substituted‐1,3,4‐oxadiazol‐2‐amines via Graphene Oxide as Catalyst under Ultrasonic Irradiation Conditions

Abstract

We disclosed herein a series of novel 5-(2,2-difluoro-1-phenylcyclopropyl)-N-substituted-1,3,4-oxadiazol-2-amines from the reaction of 2,2-difluoro-1-phenylcyclopropane carbohydrazide and various isothiocyanates in the presence of graphene oxide (GO) and 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) under conventional and ultrasonic irradiation conditions. It was found that the reaction was completed in a short period of time with good to excellent yields by virtue of attributes offered by GO catalyst. Further, the reaction underwent smoothly in ethanol and ionic liquids. Noteworthy, GO can be recycled and reused for five cycles without considerable loss in activity. The oxidative activity and morphology of GO catalyst was confirmed by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) techniques.[a] S.

Substrate‐based synthetic strategies and biological activities of 1,3,4‐oxadiazole: A review

“…Reddy et al. (2017) synthesized 5‐(2,2‐difluoro‐1‐phenylcyclopropyl)‐N‐phenyl‐1,3,4‐oxadiazol‐2‐amine 34 by conventional method, when the phenyl isothiocyanate 32 react with 2,2‐difluoro‐1‐phenylcyclopropane carbohydrazide 33 catalysed by the carbo‐catalyst graphene oxide with 1,8‐diazabicyclo [5.4.0] undec‐7‐ene and ethanol which is act as a solvent to formed a final product 34 with 81% yield (Scheme 10).…”

“…Guda et al ( 2013) describe a one-pot synthesis of 2-a mino-5-phenyl-1,3,4-oxadizole 31 by the reaction between trimethylsilyl isothiocyanate 29 and benzohydrazide 30 undergoes cyclodesulfurization reaction under basic condition in the presence of I 2 /KI gives a final compound 31 with 94% yield (Scheme 9). Reddy et al (2017) synthesized 5-(2,2-difluoro-1-phenylcyclopropyl)-N-pheny l-1,3,4-oxadiazol-2-amine 34 by conventional method, when the phenyl isothiocyanate 32 react with 2,2-difluo ro-1-phenylcyclopropane carbohydrazide 33 catalysed by the carbo-catalyst graphene oxide with 1,8-diazabicyclo [5.4.0] undec-7-ene and ethanol which is act as a solvent to formed a final product 34 with 81% yield (Scheme 10).…”

Regioselective Synthesis of 3, 5‐Disubstituted Isoxazole Catalyzed by Cu2O−ZnO Nanocomposite

“…Isoxazole is a five‐membered heterocyclic scaffold commonly encountered in many natural products and drug molecules [2] . Derivatives of isoxazole exhibit a diverse range of biological and pharmacological activities such as antithrombotic, [3] antibacterial, [4] antagonist, [5] antiviral, [6,7] antitumor, [8] anti‐HIV, [9] herbicidal, [10] insecticidal [11] and fungicidal [12] . Isoxazole core has been present in drugs such as sulfamethoxazole [13] contains antibiotic properties, muscimol [14] used as a selective GABAA agonist, ibotenic acid [15] that acts as a neurotoxin, parecoxib [16] shows COX‐2 inhibitory properties, and leflunomide [17] behaves as an immunosuppressant agent (Figure 1).…”

Synthesis of 3‐Indole Substituted Sulfonyl 4H‐Chromenes Using Recyclable Cyclometrix Polyphosphazene‐Base Catalysts

“…Heterocyclic motifs are ubiquitous throughout pharmaceutical and agrochemical industries [4,5] . The chromene core skeleton is one of the most privileged pharmacophores as it is able to interact with different kinds of cellular targets, [6–9] exhibiting a broad spectrum of significant biological activities [10] .…”

“…[2,3] Heterocyclic motifs are ubiquitous throughout pharmaceutical and agrochemical industries. [4,5] The chromene core skeleton is one of the most privileged pharmacophores as it is able to interact with different kinds of cellular targets, [6][7][8][9] exhibiting a broad spectrum of significant biological activities. [10] Among the derivatives of chromene motif, the 2amino substituted 4H-chromenes are known to possess several pharmaceutical activities such as anticancer, antifungal, antiinflammatory, antiviral, antitumor, antivascular, and anti-tubercular.…”