Synthesis of 2-Aryl/Heteroaryloxazolines from Nitriles under Metal- and Catalyst-Free Conditions and Evaluation of Their Antioxidant Activities

Abstract

The synthesis of structurally diverse 2-aryl/heteroaryloxazolines from nitriles and aminoalcohols has been achieved under metal- and catalyst-free conditions in good to excellent yields. An array of functional groups are well-tolerated, thus, allowing the introduction of many important biologically active motifs such as azoles, ring-fused azoles, saturated heterocyclics, and amines in 2-aryloxazoline scaffolds. An evaluation of the antioxidant properties using the DPPH (diphenyl picryl hydrazyl) assay method shows the pyrrole-functionalized 2-aryloxazoline to be the best antioxidant among all the synthesized 2-aryl/heteroaryloxazolines.

A Base‐ and Metal‐free Protocol for the Synthesis of 2‐Aryl/heteroaryl Thiazolines

“…Encouraged by our recently developed, metal‐ and catalyst‐ free method for the synthesis of 2‐aryl/heteroaryloxazolines from nitriles, as a next logical step, we envisioned a direct synthesis of 2‐arylthiazolines from the reaction of aryl nitriles and aminothiols under the same reaction conditions.…”

“…This selective protocol for the synthesis of the mono‐thiazolines allows further derivatization of the unreacted nitrile group into different functionalities such as oxazoline and the corresponding product, 2‐(4‐(4,5‐dihydrothiazol‐2‐yl)phenyl)‐4,5‐dihydrooxazole 14, was successfully synthesized in 35% yield by refluxing 8k and ethanolamine 13 in the presence of Na 2 CO 3 (1.0 equiv.) in MeOH at 80°C for 15h (Scheme ) . 14 is known to show effective inhibition against corrosion in wells producing oil brine…”

“…As part of our research work on the development of convenient metal‐ and catalyst‐free protocols for the synthesis of biologically important molecules,, herein, we describe an efficient and simple route for the synthesis of 2‐aryl/heteroarylthiazolines by the direct condensation of aryl/heteroaryl nitriles with cysteamine hydrochloride under base‐ and metal‐free conditions.…”

Impact of the chain extension of poly(ethylene terephthalate) with 1,3‐phenylene‐bis‐oxazoline and N,N′‐carbonylbiscaprolactam by reactive extrusion on its properties

“…1,3-PBO is a bifunctional heterocyclic compound in the group of cyclic imino ethers (imidates) which has a general formula of N C O . The synthesis of oxazolines has been published by several authors [13][14][15][16][17][18][19][20]. Preferably, oxazolines are synthesized from their corresponding nitriles and 2-aminoethanol as published for the first time by Witte and Seelinger (Scheme 1) [21][22][23][24].…”

Synthesis and Antioxidant Properties of New Oxazole-5(4<i>H</i>)-one Derivatives

“…Oxazolone and its derivatives make a prominent structure of number of well established marketed drugs such as rilmenidine, furazolidone, nifurantoin, oxaprozin, and especially linezolid, which is an active against methicillin-resistant Staphylococcus aureus. Indeed, oxazolone based derivatives have shown diverse biological and pharmacological applications such as anticancer 1,2 , antibacterial 3 , antimycobacterial against tuberculosis 4 , and antioxidant 5,6 activity.…”