UVA Light-promoted Catalyst-free Cyclization of Vinyl Selenides: Green and Efficient Synthesis of C3-Unsubstituted 2-Selanyl Benzochalcogenophenes.

A metal- and catalyst-free photo-promoted cyclization of properly substituted vinyl selenides was developed using UVA irradiation. A total of eighteen new C3-unsubstituted 2-selanyl benzochalcogenophenes (benzofurans, benzothiophenes and benzoselenophenes) were prepared in 30-86% yield after irradiation with UVA at room temperature. The usefulness of the title compounds was demonstrated in the easy functionalization of the remaining free C-H bond of the benzochalcogenophenes to form new C-Se and C-Br bonds by simple procedures. Furthermore, the reaction can be performed under natural sunlight irradiation and the solvent is easily reused further in several subsequent runs.

A greener protocol for the synthesis of phosphorochalcogenoates: Antioxidant and free radical scavenging activities.

In this contribution, a metal- and base-free protocol has been developed for the synthesis of phosphorochalcogenoates (Se and Te) by using DMSO as solvent at 50 °C. A variety of phosphorochalcogenoates were prepared from diorganyl dichalcogenides and H-phosphonates, leading to the formation of a Chal-P(O) bond, in a rapid procedure with good to excellent yields. A full structural elucidation of products was accessed by 1D and 2D NMR, IR, CGMS, and HRMS analyses, and a stability evaluation of the phosphorochalcogenoates was performed for an effective operational description of this simple and feasible method. Typical 77Se{1H} (δSe = 866.0 ppm), 125Te{1H} (δTe = 422.0 ppm) and 31P{1H} (δP = -1.0, -13.0 and -15.0 ppm) NMR chemical shifts were imperative to confirm the byproducts, in which this stability study was also important to select some products for pharmacological screening. The phosphorochalcogenoates were screened in vitro and ex vivo tests for the antioxidant potential and free radical scavenging activity, as well as to investigation toxicity in mice through of the plasma levels of markers of renal and hepatic damage. The pharmacological screening of phosphorochalcogenoates indicated that compounds have antioxidant propriety in different assays and not changes plasma levels of markers of renal and hepatic damage, with excision of 3g compound that increased plasma creatinine levels and decreased plasma urea levels when compared to control group in the blood mice. Thus, these compounds can be promising synthetic antioxidants that provide protection against oxidative diseases.

Antiparasitic activity of 1,3-dioxolanes containing tellurium in Trichomonas vaginalis.

The increased prevalence of metronidazole-resistant infections has resulted in a search for alternative drugs for the treatment of trichomoniasis. In the present study, we report the preparation and in vitro activity of three 1,3-dioxolanes that contain tellurium (PTeDOX 01, PTeDOX 02, and PTeDOX 03) against Trichomonas vaginalis. Six concentrations of these compounds were analyzed for in vitro activity against ATCC 30236 isolate of T. vaginalis. PTeDOX 01 reported a cytotoxic effect against 100% of T. vaginalis trophozoites at a final concentration of 90µM with an IC50 of 60µM. The kinetic growth curve of trophozoites indicated that PTeDOX 01 reduced the growth by 22% at a concentration of 90µM after an exposure of 12h, and induced complete parasite death at 24h. It induced cytotoxicity of 44% at 90µM concentration but and had no effect in lower concentrations in a culture of CHO-K1 cells. These results confirmed that PTeDOX 01 is an important drug for the treatment of T. vaginalis, and should be evaluated in other infectious agents as well.

Organochalcogen compounds from glycerol: synthesis of new antioxidants.

We describe here a simple method for the synthesis of glycerol derivatives containing an organochalcogen unit (Se, Te and S) using NaBH4 and PEG-400 as a solvent. The new methodology was used to synthesize a range of new organochalcogen compounds in good yields. Furthermore, four of synthesized compounds were evaluated for their antioxidant activity using different assays, such as 2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, nitric oxide (NO) and hydroxyl radical (OH) scavenging, ferric ion reducing antioxidant power (FRAP), ferrous ion chelating, superoxide dismutase-like activity and inhibition of linoleic acid lipid peroxidation. The new organotellurium 2,2-dimethyl-4-(phenyltellanylmethyl)-1,3-dioxolane 3 j showed antioxidant activity and was more effective in inhibition of induced lipid peroxidation compared to solketal 4. Selenium and sulfur analogs 3a and 3m and solketal 4 did not present antioxidant effect. These findings suggest that 2,2-dimethyl-4-(phenyltellanylmethyl)-1,3-dioxolane 3 j is a promising antioxidant and that its activity is influenced by the presence of the tellurium atom on the structure.