As imple and rapid methodf or the selective synthesis of 3-(organylselanyl)-1 H-indoles and3 -(organylselanyl)imidazo[1,2-a]pyridines catalyzed by CuI/SeO 2 under ultrasound irradiation was developed. This protocol employs adiverse range of 1 H-indoles or imidazo[1,2-a]pyridines and diorganyl diselenides to afford the corresponding products selectively in good to excellent yields. Moreover,t he antioxidant activity of these compounds was evaluated by using aw ider ange of in vitro assays,s uch as 2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1picrylhydrazyl (DPPH) radical, ferric ion reducing antioxidant power (FRAP), and inhibition of reactive speciesf ormation in mice cortex. The bioassays revealed thatb oth classes of the newly synthesized organoselenium compounds present antioxidanta ctivity,w ith emphasis on the 3-(organylselanyl)-1 Hindoles.T his pharmacological activity opens aw ide range of biological applications where the reduction of oxidative stress is essential.[a] B.
Results and DiscussionAc omparatives tudy on the use of microwaves, US, and conventional heating in the copper-catalyzed selenylation of indoles in DMSO was recently reported by us. [18b] In this reaction, Figure 1. 3-Arylselanylindoles A and B and 3-thioimidazo[1,2-a]pyridines C and D with similar effects to Combretastatin A-4a nd Enviroxime.Scheme1.Generalscheme of the present work.
Ultrasonic (US) irradiation was successfully used as an alternative energy source to prepare 3-selanylindoles through the direct selanylation of indoles with diorganyl diselenides using CuI (20 mol%) as catalyst and DMSO as the solvent. By using this US-promoted reaction, eleven 3-organylselanylindoles were prepared selectively and in good yields. A comparative study between the reactions under conventional heating, microwave and ultrasound irradiations was performed, and it was observed advantage in using US over the other heating systems.
Abstract:We describe here an efficient and regioselective synthesis of arylselanyl anilines by coppercatalyzed direct arylselenation of arylamines. Using a catalytic amount of copper iodide in dimethyl sulfoxide at 110 8C under an air atmosphere, a range of arylselanyl anilines was obtained directly from substituted diaryl diselenides in moderate to good yields via C À H bond cleavage of aryl amines.
The ionic liquid 1-butyl-3-methylimidazolium methylselenite, [bmim][SeO2(OCH3)], was successfully used as solvent in the catalyst-free preparation of 3-arylselenylindoles by the reaction of indole with ArSeCl at room temperature. The products were obtained selectively in good yields without the need of any additive and the solvent was easily reused for several cycles with good results.
Isoxazol-5-one rings have been identified as relevant motifs in drug candidates, agrochemicals, and materials. Furthermore, this heterocycle has been also applied as a versatile building block for the preparation of a variety of densely functionalized molecules. This short review will present the most representative applications of isoxazol-5-ones in organic synthesis while discussing their properties and reactivity.1 Introduction1.1 General Aspects1.1.1 Tautomerism1.1.2 Importance: Natural Products Isolation, Biological Activity, and Materials1.1.3 Preparation Methods2 Isoxazol-5-ones in Organic Synthesis2.1 General Reactivity2.2 Specific Examples2.2.1 Alkylation Strategies2.2.2 Alkyne Synthesis2.2.3 Annulation Reactions2.2.4 N–O Bond Insertions2.2.4.1 Preparation of 1,3-Oxazin-6-ones3 Conclusions
Herein we report the use of ultrasonic irradiation (US) in the synthesis of six new semi-synthetic selenium-containing chrysin derivatives by a simple and effective methodology utilizing CuI as catalyst, in good to excellent yields (60-89%). It was observed that US accelerates the reaction compared to conventional heating with excellent selectivity for diselenylated products. Compounds were tested for their antioxidant and anticancer activities in vitro and it was observed that the presence of selenium in the A-ring of chrysin enhanced both antioxidant and anticancer properties. Semi-synthetic 6,8-bis(o-tolylselanyl)-chrysin 3b has the best radical scavenging activity of DPPH (I: 39.79µM) and ABTS (IC: 6.5µM) radicals. Similarly, in the Reactive Species (RS) assay, 3b showed high antioxidant activity in mice cortex (IC: 5.67µM), whereas 6,8-bis(p-anisoylselanyl)-chrysin 3c was the more active in the hippocampus (IC: 5.63µM). The Se-chrysins were effective in prevention of lipid peroxidation, highlighting 6,8-bis(p-fluorophenylselanyl)-chrysin 3d in cortex (IC: 0.54µM) and 3b in hippocampus (IC: 0.27µM). In addition, 3d was effective in inhibiting human lung adenocarcinoma (A549) cells growth, with a IC of 19.9µM after 72h of treatment, while 6,8-bis(p-anisoylselanyl)-chrysin 3c presented the higher antiproliferative activity after 48h of treatment (IC of 41.4µM).
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