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Herein we present an alternative and transition-metal-free procedure to access 3-organoselanylthiochromones and 3-organoselanylchromones from the cyclization reaction between alkynyl aryl ketones and diorganyl diselenides promoted by Oxone®.

We describe our results for the synthesis of 2′-(1,2,3-triazoyl)-acetophenones by copper catalyzed azide–alkyne cycloaddition of 2′-azidoacetophenone with alkynes. The corresponding 2′-(1,2,3-triazoyl)-acetophenones were obtained in moderate to excellent yields and according to our experiments, it was observed that ultrasound accelerates the reaction compared to conventional heating. In addition, the obtained compounds were screened by molecular docking for their possible inhibitory effect on the activity of monoamine oxidase (MAO), an enzyme responsible for the degradation of monoamine neurotransmitters. Three compounds were selected and presented an inhibitory effect on both MAO-A and B isoform activities in vitro. These new MAO inhibitors may be of interest to treat monoamine deficit related-neuropsychiatric disorders, such as depression and Parkinson's disease.

We describe herein an alternative and transition-metal-free procedure for the access of benzo[b]chalcogenophenes fused to selenophenes via intramolecular cyclization of 1,3-diynes. This efficient protocol involves a double cyclization of 1,3-diynyl chalcogen derivatives promoted by the electrophilic species of organoselenium generated in situ by the oxidative cleavage of the Se-Se bond of dibutyl diselenide using Oxone® in acetonitrile as solvent in an open-flask at 80 °C. In this study, 15 selenophenes with broad substrate scope were prepared in moderate to excellent yields (55-98%) with short reaction times (0.5-3.0 h).

We described here our results on the use of thiourea as a ligand in the copper catalysed azide-alkyne cycloaddition (CuAAC) of 2-azidobenzaldehyde with alkynes. Reactions were performed reacting 2-azidobenzaldehyde with a range of terminal alkynes using 10 mol % of copper iodide as a catalyst, 20 mol % of thiourea as a ligand, triethylamine as base, DMSO as solvent at 100 °C under nitrogen atmosphere. The corresponding 2-(1H-1,2,3-triazoyl)-benzaldehydes (2-TBH) were obtained in moderated to excellent yields and according our experiments, the use of thiourea decreases the formation of side products. The obtained compounds were screened for their binding affinity with multiple therapeutic targets of AD by molecular docking: β-secretase (BACE), glycogen synthase kinase (GSK-3β) and acetylcholinesterase (AChE). The three compounds with highest affinity, 5 a (2-(4-phenyl-1H-1,2,3-triazol-1-yl)benzaldehyde), 5 b (2-(4-(p-tolyl)-1H-1,2,3-triazol-1-yl)benzaldehyde), and 5 d (2-(4-(4-(tert-butyl)phenyl)-1H-1,2,3-triazol-1-yl)benzaldehyde) were selected and evaluated on its antioxidant effect, in view of select the most promising one to perform the in vivo validation. Due the antioxidant potential ally to the affinity with BACE, GSK-3β and AChE, compound 5 b was evaluated in a mouse model of AD induced by intracerebroventricular injection of streptozotocin (STZ). Our results indicate that 5 b (1 mg/kg) treatment during 20 days is able to reverse the cognitive and memory impairment induced by STZ trough the modulation of AChE activity, amyloid cascade and GSK-3β expression.

Two new Cu(II) complexes based on 4-(arylchalcogenyl)-1H-pyrazoles monodentate bis(ligand) containing selenium or sulfur groups (2a and 2b) have been synthesized and characterized by IR spectroscopy, high-resolution mass spectrometry (HRMS), and by X-ray crystallography. In the effort to propose new applications for the biomedical area, we evaluated the antioxidant activity and cytotoxicity of the newly synthesized complexes. The antioxidant activity of the Cu(II) complexes (2a - 2b) were assessed through their ability to inhibit the formation of reactive species (RS) induced by sodium azide and to scavenge the synthetic radicals 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS

A peroxide-mediated protocol for the synthesis of 2-substituted benzothiazoles was developed, starting from bis(o-aminophenyl) disulfides and primary alcohols. Eleven differently 2-substituted benzothiazoles were prepared in moderate to excellent yields using di-tert-butyl peroxide (DTBP) as an oxidant.

The derivatization of chitosan (CS) is widely exploited to endow this polysaccharide with enhanced physicochemical and biological properties. Beyond the synthetic route, the nature of the compounds used to functionalize the CS-derivatives exerts a pivotal role in their final properties. Making use of a simple “click” reaction, we synthesized for the first time an organoselenium-CS derivative through a 1,2,3-triazole formation. The product (CS-TSe) was characterized in detail by FTIR, NMR (1H, 13C, and 77Se) and UV–Vis techniques, and SEM microscopy. The antioxidant activity of CS-TSe was examined by ABTS+ and DPPH (free radical-scavenging) assays. Experimentally, it was demonstrated that CS-TSe has superior antioxidant activity compared with raw CS and “free” organoselenium compound, suggesting a benign and synergistic effect due to the derivatization. In short, the antioxidant property of CS-TSe combined with the other attractive properties of CS and selenium could be useful in the formulation of advanced materials for biomedical and packaging applications.

An efficient copper-catalyzed multicomponent reaction was developed for the synthesis of (arylselanyl)- or (arylsulfenyl)-alkyl-1,2,3-triazolo-1,3,6-triazonines. The products were obtained in moderate to excellent yields via the reaction of o-phenylenediamine, 2-azidobenzaldehyde and different arylchalcogenyl alkynes using catalytic copper iodide in 1,4-dioxane at 100 °C. The reactions tolerated a range of substituents on the arylchalcogenyl alkynes and proved to be an efficient methodology for the combinatorial synthesis of new selenium or sulfur-containing triazonine derivatives.

We present here the synthesis of novel (Z)-2-organylselanyl ketoximes by nucleophilic substitution reaction of E/Z mixtures of 2-bromo ketoximes with nucleophilic species of selenium, which were generated in situ by simple cleavage of diorganyl diselenides with NaBH4 using ethanol/THF as solvent. The new 2-organylselanyl ketoximes were synthesized in moderate to good yields and with selectivity for the (Z)-configuration. The synthesized (Z)-2-arylselanylacetophenone oximes were submitted to the Beckmann rearrangement, furnishing the corresponding N-aryl-2-(selanyl)acetamides. (Z)-1-Phenyl-2-(phenylselanyl) ketoxime has antifungal activity against Sphaceloma ampelinum and a good level of antioxidant activity in vitro in DPPH, ABTS, FRAP and lipid peroxidation assays.

Background: The main constituents of Cymbopogonnardus (L) Rendle and C. citratus (DC) Stapfessential oils are (R)-citronellal and citral, respectively. Organochalcogen compounds can boost the biological activities of natural products. Methods: Several chalcogen-containing nitrones derived from (R)-citronellal and citral were prepared and evaluated for their antimicrobial and antioxidant activities. The antimicrobial activity was evaluated by the disc diffusion test and the antioxidant properties were evaluated in vitro by DPPH (1,1-diphenyl-2-picryl-hydrazyl), ABTS (2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), and FRAP (ferric ion reducing antioxidant power) assays. Results: In the antimicrobial assay, (E)-N,3,7-trimethyl-3-(phenylthio)oct-6-en-1-imine oxide 5c exhibited halos between 21.5 mm (Escherichia coli O157:H7) and 26.0 mm (Listeria monocytogenes), while (E)-N,3,7-trimethyloct-6-en-1-imine oxide 5d presented halos between 22.5 mm (E. coli O157:H7) and 31.0 mm (L. monocytogenes). (E)-N,3,7-Trimethyl-2-(phenylthio)oct-6-en-1-imine oxide 5a showed the lowest minimal inhibitory concentration (MIC) value against Bacillus cereus (0.48 mM), and 5c was the most potent bactericide, with a minimal bactericidal concentration (MBC) of 0.52 mM for E. coli O157:H7. In the antioxidant assays, 5c, 5d, and 10 ((E)-3,7-dimethyl-2-(phenylselanyl)oct-6-enal oxime) were the most actives in the DPPH, ABTS, and FRAP assays, respectively. Conclusions: The presence of a phenylthio group in the nitrone increases its antimicrobial activity against Gram-positive and Gram-negative foodborne pathogens in the disk diffusion test and the antioxidant activity in vitro.

In order to investigate the use of semi-synthetic antimicrobial compounds, the objective of this study was to evaluate the 3-(p-chlorophenyl)thio citronellal, a novel compound that is derived from the essential oil of Cymbopogon citratus, against spoilage and pathogenic bacteria in food. This study also evaluated the possible mechanisms of action and cellular targets. Qualitative and quantitative tests and scanning electron microscopy were used to compare 3-(p-chlorophenyl)thio citronellal with citral and (R)-citronellal. It was observed that 3-(p-chlorophenyl)thio citronellal is a potent antimicrobial agent with bactericidal activity against different pathogenic and spoilage bacteria, of which the Gram-positive species were the most sensitive. The minimal inhibitory concentration for 3-(p-chlorophenyl)thio citronellal was approximately 100 times lower than that of citral, and this was corroborated by the kinetic curve of action, demonstrating that cell death was faster when the bacterial cells were treated with 3-(p-chlorophenyl)thio citronellal. This finding showed that the addition of thiol enhances the bioactivity of citral. In vitro testing showed that the compound does not show toxicity. The SEM images showed cell damage with the formation of pores in the cell wall and membrane, which are possibly the cellular targets of the compound.

Psidium cattleianum Sabine (Myrtacea) is rich in vitamin C and phenolic compounds, including epicatechin and gallic acid as the main components.To evaluate the antifungal and antioxidant capacity in vitro of the essential oil of araçá (EOA). The acute toxicity of the EOA also was evaluated in mice.The leaves of the P. cattleianum were extracted by steam distillation. The antioxidant capacity was evaluated by in vitro tests [1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), ferric ion reducing antioxidant power (FRAP), linoleic acid oxidation, thiobarbituric acid reactive species (TBARS)], and ex vivo analysis [TBARS, δ-aminulevunilate dehydratase (δ-Ala-D) and catalase activity, non-protein thiols (NPSH), and ascorbic acid levels]. The toxicity was studied in mice by a single oral administration of EOA; and the antifungal activity was performed with five strains of fungi.The EOA exhibited antioxidant activity in the FRAP assay and reduced lipid peroxidation in the cortex (Imax = 32.90 ± 2.62%), hippocampus (IC50 = 48.00 ± 3.00 µg/ml and Imax = 32.90 ± 2.62%), and cerebellum (Imax = 45.40 ± 14.04%) of mice. Acute administration of the EOA by the oral route did not cause toxicological effects in mice (LD50 500 µg/ml). The EOA also showed antifungal activity through of the determination minimum inhibitory concentration (MIC) values ranging from 41.67 ± 18.04 to 166.70 ± 72.17 µg/ml for tested strains.The results of present study indicate that EOA possess antioxidant properties, antifungal and not cause toxicity at tested doses.

We present herein our results on the nucleophilic addition of imidazole to a range of arylselanylalkynes by simple heating in DMF without any additives to give ( Z )-1-(1-organyl-(2-arylselanyl)vinyl)-1H-imidazoles. The reactions were performed under mild conditions with a range of arylselanylalkynes in good yields and with high regio- and stereoselectivity to give the respective (Z)-arylselanyl alkene as the only isomer.

A convenient approach to the Cu-catalyzed coupling of diphenyl disulfide and diphenyl ditelluride with vinyl bromides using a recyclable catalytic system and glycerol as a green solvent is described. This protocol was efficiently used in the preparation of vinyl sulfides and vinyl tellurides with a variety of substituents in good yields and stereoselectively. The solvent/catalyst system was directly reused for four cycles without loss of activity.

The title compounds were synthesized by a one-pot reaction of diaryl diselenides with terminal alkynes avoiding the previous preparation of arylselanyl alkynes. The reactions were performed under mild conditions with a range of terminal alkynes using KF/Al2O3 and PEG-400 as solvent. The addition of diaryl diselenides to alkynes occurred stereoselectively to give exclusively (Z)-1,2-bis-arylselanyl alkenes in good yields. The reaction time was reduced to a few minutes using microwave irradiation and the KF/Al2O3/PEG-400 system can be reused one time without previous treatment with comparable activity.

Here we describe a simple, clean, and efficient solvent-free protocol for the synthesis of bis(indolyl)methanes promoted by silica gel. The products were obtained in good to excellent yields through the reaction of indoles with cyclohexanone and a range of aldehydes. The silica gel was easily recovered and utilized for further reactions without loss of activity.

Essential oil (EO) of the leaves of Eugenia uniflora L. (Brazilian cherry tree) was evaluated for its antioxidant, antibacterial and antifungal properties. The acute toxicity of the EO administered by oral route was also evaluated in mice. The EO exhibited antioxidant activity in the DPPH, ABTS and FRAP assays and reduced lipid peroxidation in the kidney of mice. The EO also showed antimicrobial activity against two important pathogenic bacteria, Staphylococcus aureus and Listeria monocytogenes, and against two fungi of the Candida species, C. lipolytica and C. guilliermondii. Acute administration of the EO by the oral route did not cause lethality or toxicological effects in mice. These findings suggest that the EO of the leaves of E. uniflora may have the potential for use in the pharmaceutical industry.

In this study, the antioxidant and antidepressant-like effects of α-(phenylselanyl) acetophenone (PSAP), an organoselenium compound, were investigated. To assess the in vitro antioxidant properties, PSAP was evaluated in four test systems (DPPH, ABTS, FRAP and inhibition of lipid peroxidation). PSAP (100-500 μM) showed potent antioxidant activity and protected against lipid peroxidation. Additionally, we investigated whether PSAP, when administered in mice (100, 200 and 400mg/kg, per oral, p.o.), could cause acute toxicity. Our results demonstrated that PSAP did not cause the death of any animal, significantly reduce body weight or cause any oxidative tissue stress following treatment. This study also evaluated the effect of PSAP (0.1-10 mg/kg, p.o) on mice in a forced swim test (FST) and tail suspension test (TST), assays that are predictive of depressant activity and motor activity in the open-field. PSAP (5-10 mg/kg) significantly reduced immobility time in the FST and TST without affecting motor activity. In addition, the antidepressant-like effect caused by PSAP (5m/kg, p.o) in mice during the TST was dependent on an interaction with the serotonergic system (5-HT(1A) receptors), but not with the noradrenergic, dopaminergic or adenosinergic system. Together, these results suggest that PSAP possesses antioxidant and antidepressant-like properties and may be of interest as a therapeutic agent for the treatment of depressive disorders.

We present here a clean, solvent-free hydrothiolation of alkynes using solid supported catalyst (Al 2 O 3 /KF). This efficient and improved method selectively furnishes the corresponding anti-Markovnikov vinyl sulfides in good to excellent yields. The method is applicable for aliphatic and aromatic thiols and the catalytic system can be re-used up to two times without previous treatment and with comparable activity.

A general, clean and easy method for the conjugated addition of thiols to citral promoted by KF/Al 2 O 3 under solvent-free conditions at room temperature or under MW irradiation is described. It was found that the same protocol is applicable to the direct reaction of thiophenol with essential oil of lemon grass ( Cymbopogon citratus ) to afford directly 3-thiophenylcitronellal, a potential bactericide agent. The method was extended to others electron-poor alkenes with excellent results. The catalytic system can be reused up to three times without previous treatment with comparable activity.

We present here the reaction of diphenyl dichalcogenides (Se and Te) with propargyl alcohols using alumina supported sodium borohydride under solvent-free conditions. This efficient and improved method is general and furnishes the corresponding vinyl chalcogenide preferentially with a Z configuration. We also observed that when the same protocol was applied to phenyl acetylene, the (E)-bis-organochalcogen alkenes were obtained in good yields and high selectivity. The use of MW irradiation facilitates the procedure and accelerates the reaction.

A green and efficient method for the synthesis of octahydroacridine (OHA) has been developed by a simple one-pot hetero-Diels–Alder reaction starting from (+)-citronellal and N -arylamines in the presence of a solid supported catalyst (SiO 2 /ZnCl 2 ), under MW irradiation and without any solvent. The method was used in the direct preparation of OHA from citronella oil in good yield.

A simple green and efficient method has been developed for the synthesis of (−)-isopulegol from (+)-citronellal in the presence of a solid supported catalyst (SiO2/ZnCl2), under solvent-free conditions and MW irradiation. It was also found that the same technology is applicable to the direct preparation of (−)-isopulegol from the essential oil of citronella (Cymbopogon nardus, growing in southern Brazil) in excellent yield.

A very simple procedure is described for the efficient synthesis of vinyl sulfides by hydrothiolation of terminal alkynes using 1- n -butyl-3-methylimidazolium methylselenite, [bmim][SeO 2 (OCH 3 )]. The reaction proceeds cleanly under mild, base-free conditions and was performed with aromatic and aliphatic thiols.

We describe here our results on the use of choline chloride/urea 1:2 as a deep eutectic solvent (DES) in the synthesis of vinyl selenides. A good selectivity for the (E)-1,2-bis-organylseleno alkenes was observed starting from terminal alkynes and diaryl or dibutyl diselenides in the presence of NaBH4. The reaction of 1,3-butadiynes with diphenyl diselenide afforded exclusively the respective mono-selenylated (Z)-alkenynes. Diphenyl ditelluride reacted with phenylacetylene and 1,4-diphenyl-but-1-en-3-yne affording (Z)-phenyltelluro alkenes in good yields.

Reaction of cyanomethylphosphonate with aryl selenenyl (or tellurenyl) halides and aldehydes, under basic conditions, provides α-phenylseleno or α-phenyltelluro acrylonitriles in good yields. Reaction of the α-phenylseleno acrylonitriles with dienes furnishes the corresponding adducts while reaction with amines furnishes α-phenylseleno-β-amino nitriles. Selective reduction of the cyano group with DIBAL-H results in the α-phenylseleno-α,β-unsaturated aldehydes.

We describe herein the use of glycerol as an efficient and a recyclable solvent in the thioacetalization of aldehydes and ketones. The catalyst-free reactions proceed easily using glycerol at 90 °C and the corresponding thioacetals were obtained in good to excellent yields. Glycerol was recovered and utilized for further thioacetalization reactions.

2-Phenylseleno aldehydes and ketones were selectively obtained using solid-supported catalyst (KF/Al2O3) and PEG-400 as clean, recyclable medium in good to excellent yields. The method was applied in the preparation of highly functionalized 2-phenylseleno citronellal and citronellol, potential bactericide agents. The catalytic system KF/Al2O3 and PEG-400 can be re-used for four times without previous treatment.

The new acidic ionic liquid phenyl butyl ethyl selenonium tetrafluoroborate, [pbeSe]BF 4 , was successful used as a co-catalyst in the Baylis–Hillman reaction of aldehydes and electron-deficient alkenes. The Baylis–Hillman adducts were obtained in moderated to good yields and in relatively short reaction times under mild conditions.

A general and easy method for the synthesis of several 1,2-disubstituted benzimidazoles using SiO2/ZnCl2 and solvent-free conditions is described. This efficient and improved method furnishes selectively and in good yields the corresponding 1,2-bis(organyl)-benzimidazoles starting from o-phenylenediamine and aromatic or aliphatic aldehydes. The catalytic system was re-used up three times and the use of focused microwaves accelerates the reaction.

The treatment of isomeric vinylic tellurides 5–7 with butyllithium in THF at −78 °C in the presence of a carbonyl compound such as benzaldehyde or cyclohexanone was studied. High selectivity of the attack at the tellurium atom was observed. In most cases, the corresponding allylic alcohol was obtained as the only (or major) product instead of the alcohols derived by the 1,2 addition of BuLi at the carbonyl compound. Similar results were obtained using the ketenetelluroacetal 14 instead of the vinylic monotellurides.

Reaction of thiomethyl phosphonates with aryl (or butyl) tellurenyl halides and aldehydes under basic conditions provides moderate to good yields of ketene thio (telluro) acetals, with vinylic sulfides being byproducts of this transformation. Tellurium-lithium exchange by reaction with n-BuLi yielded vinyl organolithium species, which were captured with several electrophiles. In the case of DMF, Z-α-phenylthio-α,β-unsaturated aldehydes were obtained.

Acidic ionic liquid butyl ethyl phenyl selenonium tetrafluoroborate, [BEPSe]BF4, was successfully employed as a catalyst for the synthesis of several dithioacetals in the absence of a solvent. The method is general and selectively afforded thioacetals derived from aldehydes and ketones in good yields.

We present here a fast, solvent-free synthesis of symmetrical disulfides using solid supported catalyst (Al2O3/KF). The reaction was performed at room temperature, by gentle heating or under MW irradiation. This efficient and improved method is general for liquid thiols, affording the disulfides in good to excellent yields. The catalytic system can be re-used two times without previous treatment and with comparable activity.

A general and easy method for the synthesis of several selenonium and telluronium salts is described. These compounds are acidic liquids at room temperature and were obtained in excellent yields. Phenyl butyl ethyl selenonium tetrafluoroborate was employed in the hetero-Diels–Alder cyclization of aryl imines derived from citronellal, affording octahydroacridines in good yields.

New and efficient methods were developed to prepare ketene organyltelluroacetals in moderate to excellent yields. This was accomplished by reaction of phenyl- or butyltelluromethylphosphonates with phenyl- or butyltellurenyl halides and aldehydes or cyclohexanone, under basic conditions. This Horner–Wittig protocol allows the preparation of several new tri- and tetra-substituted olefins.

We described herein the use of glycerol as a novel solvent in the cross-coupling reaction of diaryl diselenides with vinyl bromides catalyzed by CuI. This cross-coupling reaction was performed with diaryl diselenides and (Z)- or (E)-vinyl bromides bearing electron-withdrawing and electron-donating groups, affording the corresponding vinyl selenides in good to excellent yields. The mixture glycerol/catalyst can be directly reused for further cross-coupling reactions.

We present here the results on the use of 1- n -butyl-3-methylimidazolium methylselenite, [bmim][SeO 2 (OCH 3 )], in the synthesis of symmetrical disulfides starting from thiols. This efficient and improved method is general for aromatic, aliphatic, and functionalized thiols affording the disulfides in good to excellent yields after easy work up. The use of a microwave accelerates the reaction and the [bmim][SeO 2 (OCH 3 )] was reused for further oxidation reactions.

We describe herein the use of glycerol as an efficient, safe and recyclable solvent in the one-pot hetero-Diels–Alder (HDA) reaction of ( R )-citronellal with substituted arylamines. The catalyst-free reactions proceed easily using glycerol at 90 °C and the corresponding octahydroacridines (OHAs) were obtained in good to excellent yields by simply decantation of products. After removing the products, glycerol was directly reused for further HDA reactions without lost of activity.

PEG-400 and glycerol were successfully used as recyclable solvents for the synthesis of several organylthioenynes in good to excellent yields and high selectivity using solid supported catalyst (KF/Al2O3). This easy, general and improved method furnishes the corresponding alkenyl sulfides preferentially with Z configuration. The catalytic system and the glycerol or PEG-400 can be reused up to three times without previous treatment with comparable activity.

An overview on the applications of the Whig and Homer-Wittig reactions to the synthesis of vinylic sulfides, ketene dithioacetals. 1,3-dithioles, 1,4-benzodithiafulvenes, 1.4-benzodithia-fulvenes, vinylic sulfoxides, vinylic sulfones, vinylic selenides, ketene selenoacetals, vinylic tellurides, ketene phenyltelluroacetals, ketene dithioacetal mono-S-oxides, ketene (S, Te) acetals and chalcogeno allenes is presented.