Design, synthesis and biological evaluation of 1,3-dihydroxyxanthone derivatives: Effective agents against acetylcholinesterase

The present work concerns the rational design and development of new inhibitors of acetylcholinesterase (AChE) based on the privileged xanthone scaffold. In order to understand and rationalize the mode of action of these target structures a theoretical study was initially conducted. From the results of rational design, a new variety of amphiphilic xanthone derivatives were synthesized, structurally characterized and evaluated as potential anti-Alzheimer agents. The results showed that most of the synthesized compounds exhibited high AChE inhibitory activity at the micromolar range (IC50, 0.46–12.09 μM). The synthetic xanthone 11 showed the best inhibitory effect on AChE and a molecular modeling study revealed that 11 targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Therefore, this compound could be considered as a potential lead compound towards new drugs for the treatment of Alzheimer’s disease.Fil: Menéndez, Cintia Anabella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Biscussi, Brunella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Accordino, Sebastian Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Murray, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Appignanesi, Gustavo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

A new antagonist of caenorhabditis elegans glutamate-activated chloride channels with anthelmintic activity

Nematode parasitosis causes significant mortality and morbidity in humans andconsiderable losses in livestock and domestic animals. The acquisition of resistanceto current anthelmintic drugs has prompted the search for new compounds for whichthe free-living nematode Caenorhabditis elegans has emerged as a valuable platform.We have previously synthetized a small library of oxygenated tricyclic compoundsand determined that dibenzo[b,e]oxepin-11(6H)-one (doxepinone) inhibits C. elegansmotility. Because doxepinone shows potential anthelmintic activity, we explored itsbehavioral effects and deciphered its target site and mechanism of action on C. elegans.Doxepinone reduces swimming rate, induces paralysis, and decreases the rate ofpharyngeal pumping required for feeding, indicating a marked anthelmintic activity. Toidentify the main drug targets, we performed an in vivo screening of selected strainscarrying mutations in Cys-loop receptors involved in worm locomotion for determiningresistance to doxepinone effects. A mutant strain that lacks subunit genes of theinvertebrate glutamate-gated chloride channels (GluCl), which are targets of the widelyused antiparasitic ivermectin (IVM), is resistant to doxepinone effects. To unravel themolecular mechanism, we measured whole-cell currents from GluCla1/b receptorsexpressed in mammalian cells. Glutamate elicits macroscopic currents whereas noresponses are elicited by doxepinone, indicating that it is not an agonist of GluCls.Preincubation of the cell with doxepinone produces a statistically significant decrease ofthe decay time constant and net charge of glutamate-elicited currents, indicating that itinhibits GluCls, which contrasts to IVM molecular actions. Thus, we identify doxepinoneas an attractive scaffold with promising anthelmintic activity and propose the inhibitionof GluCls as a potential anthelmintic mechanism of action.Fil: Castro, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Turani, Ornella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Faraoni, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Bouzat, Cecilia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; Argentin

Sonochemical synthesis of bis(tri-n-butylstannyl) aromatic compounds via Barbier-like reactions

This paper reports a study of the synthesis of aryltri-n-butylstannanes via a sonochemical Barbier reaction of aryl- and heteroaryl bromides with bis(tri-n-butyltin) oxide (2) in THF. Our results demonstrate that, despite previous reports on contrary, the aryltributylstannanes can also be obtained under the same reaction conditions via sonicated reactions between aryl monobromides and tri-nbutyltin chloride (2). A comparative study of the reactions of electrophiles 2 and 3 with bromobenzene, 2-bromopyridin, o- and m-bromoanisole, m-bromotoluene, 9-bromophenthrene, and 9-bromoanthracene, indicates that the corresponding aryl- and heteroaryl-tri-n-butylstannyl derivatives are obtained in about the same yields. Best reaction conditions and the results obtained in the investigation of the sonicated reactions between several aromatic and heteroaromatic dibromides are also reported. It was found that the reactions using 1,2-, 1,3-, and 1,4-dibromobenzenes, 4,40-dibromobiphenyl, 1,4-dibromonaphthalene, 2,5- and 3,5-dibromopyridines, and 2,5-dibromothiophene lead to the corresponding bis(tri-n-butylstannylated) derivatives in many cases in very high yields. Also the excellent results obtained in the sonicated reactions of 1,3,5-tribromobenzene with 2 and 3 are reported.Fil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Fidelibus, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Mandolesi, Sandra Delia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Ocampo, Romina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Scoccia, Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Podestá, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur; Argentin

Synthesis of organotin derivatives of optically active eleven-membered macrodiolides

The synthesis and the results obtained in the hydrostannation of eight new TADDOL diacrylates and methacrylates are reported. The addition of triorganotin hydrides, R3SnH, 12-14 (R = nBu, neophyl, Ph, respectively) to diesters 6-11 containing different combinations of substituents at the C-2 carbon of the dioxolane ring, led to macrocyclization products in all cases. The cyclohydrostannation of diacrylate 10 proceeded with complete diastereoselectivity. The cyclohydrostannation of diesters 33 and 34 with hydrides 12 and 14 in all cases only afforded one stannylated macrocycle.Fil: Scoccia, Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Podestá, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Palladium-catalyzed stereoselective hydrostannation of substituted propargyl alcohols with trineophyltin hydride

This paper reports results obtained in a study on the palladium-catalyzed hydrostannation of substituted propargyl alcohols with the bulky trineophyltin hydride (1). The reaction of 1 with 10 propargyl alcohols containing one up to three substituents, was carried out in THF at room temperature leading to the corresponding allylstannanes following in all cases a syn addition stereochemistry. These additions took place in good to excellent yields and, mostly, with a high degree of stereoselectivity. The results obtained suggest that the observed α/β regioselectivity might be ascribed to the steric bulk of the proximal substituents rather than to electronic effects. Full 1H-, 13C-, and 119Sn NMR characteristics are included. © 2008 Elsevier B.V. All rights reserved.Fil: Faraoni, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Química; ArgentinaFil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Química; ArgentinaFil: Podestá, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Química; Argentin

Nucleophile- or light-induced synthesis of 3-substituted phthalides from 2-formylarylketones

The surprisingly facile conversion (isomerization) of 2-formyl-arylketones into 3-substituted phthalides, as observed for the marine natural product pestalone and its per-O-methylated derivative, was investigated using a series of simple 2-acylbenzaldehydes as substrates. The transformation generally proceeds smoothly in DMSO, either in a Cannizarro-Tishchenko-type reaction under nucleophile catalysis (NaCN) or under photochemical conditions (DMSO, 350 nm). © 2012 American Chemical Society.Fil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Cologne; AlemaniaFil: Augner, Daniel. University of Cologne; AlemaniaFil: Slavov, Nikolay. University of Cologne; AlemaniaFil: Schmalz, Hans Günther. University of Cologne; Alemani

A Green Nanopalladium-Supported Catalyst for the Microwave-Assisted Direct Synthesis of Xanthones

We report an efficient, selective, rapid and eco-friendly protocol for the one-step synthesis of a small xanthone library via an intermolecular catalytic coupling from readily available salicylaldehydes and 1,2-dihaloarenes under ligand-free conditions. To achieve this advantageous direct annulation, we used a novel recoverable palladium nanocatalyst supported on a green biochar under microwave irradiation. Unlike other existing palladium-based approaches, our synthetic strategy showed a greater operational simplicity, drastic reduction in reaction times, and an excellent tolerance to diverse functional groups. The reaction proceeds in very good yields and with high regioselectivity. The novel heterogeneous catalyst can be recycled and reused up to four times without significant loss of activityFil: Steingruber, Hugo Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Mendioroz, Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Diez, Alejandra Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Convenient One-Pot Synthesis of 9 H -Carbazoles by Microwave Irradiation Employing a Green Palladium-Based Nanocatalyst

An efficient palladium-catalyzed tandem reaction for the one-pot synthesis of 9 H -carbazoles under microwave irradiation is developed. This approach involves a sequential Buchwald-Hartwig amination and a direct arylation from affordable and inexpensive anilines and 1,2-dihaloarenes. For the development of this purpose, a novel and magnetically recoverable palladium nanocatalyst supported on a green biochar under ligand-free conditions is used. Compared to other existing palladium-based protocols, the present synthetic methodology shows a drastic reduction in reaction times and excellent compatibility with different functional groups allowing to obtain a small library of 9 H -carbazoles in high yields and with good regioselectivity. This procedure represents the first example in the direct synthesis of carbazoles using a heterogeneous palladium nanocatalyst from commercial precursors. To examine the application of this protocol, a direct and scalable synthesis of the bioactive carbazole alkaloid clausenalene from commercially available starting materials is described.Fil: Steingruber, Hugo Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Mendioroz, Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Volpe, María Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Stereoselective radical tandem cyclohydrostannation of optically active di-unsaturated esters of TADDOL

This paper reports the results obtained in a study on the radical addition of triorganotin hydrides, R3SnH (R = Me, n-Bu, Ph; Neophyl), to four TADDOL unsaturated diesters. It was found that diese reactions lead in high yields to products of cyclohydrostannation. It was also found that whereas the addition of these hydrides to TADDOL diacrylate and TADDOL dimethacrylate leads to the expected mixtures of two and four cycloundecane diastereoisomers, respectively, the addition of triphenyltin hydride to TADDOL disubstituted acrylates yields only four out of the 16 possible stereoisomers. The observed high stereoselectivity is consistent with the radical tandem cyclohydrostannation mechanism proposed. Only in the case of the hydrostannation of TADDOL diacrylate with trimethyl- and triphenyltin hydrides could the diastereoisomers obtained in higher proportion (5a and 8a) be isolated in pure form. The subsequent reduction (lithium aluminum hydride) of macrolides 5a and 8a afforded the corresponding optically active diols 26 and 27 in high yield. Full 1H, 13C, and 119Sn NMR data are given. © 2008 American Chemical Society.Fil: Gerbino, Darío César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Koll, Liliana Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Mandolesi, Sandra Delia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Podestá, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Stereoselective synthesis of 4-oxo-2,5-dienes and conjugated dienes by Stille cross coupling reactions of vinylstannanes

The palladium-catalyzed cross coupling reactions between trineophylstannylvinyl esters and unsaturated acyl chlorides lead mostly to 4-oxo-2,5-dienes in good yields (60-77%). In some cases homocoupling products are also formed. On the other hand, the Stille reaction of Z-di- and trisubstituted vinyl iodides with trineophylvinylstannanes enables the synthesis of polysubstituted butadienes in moderate to good yields (40-60%).Fil: Fidelibus, Pablo Martin. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Gerbino, Darío César. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Mandolesi, Sandra Delia. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; ArgentinaFil: Podestá, Julio Cesar. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin