Publications by authors named "Alejandra G Suarez"

Blister agents damage the skin, eyes, mucous membranes and subcutaneous tissues. Other toxic effects may occur after absorption. The response of the Scientific Advisory Board (SAB) of the Organisation for the Prohibition of Chemical Weapons (OPCW) to a request from the OPCW Director-General in 2013 on the status of medical countermeasures and treatments to blister agents is updated through the incorporation of the latest information.

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Breast cancer is the leading cause of cancer death among women worldwide. For this reason, the development of new therapies is still essential. In this work we have analyzed the antitumor potential of levoglucosenone, a chiral building block derived from the pyrolysis of cellulose-containing materials such as soybean hulls, and three structurally related analogues.

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The discovery of efficient organocatalysts is generally carried out by thorough experimental screening of different candidates. We recently reported an efficient organocatalyst for iminium-ion-based asymmetric Diels-Alder reactions following a rational design approach. This result encouraged us to test this optimal catalyst in the mechanistically related Friedel-Crafts alkylation of indoles, but to our surprise, almost null enantioselectivity was observed.

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A series of levoglucosenone-derived 1,2,3-triazoles and isoxazoles featuring a flexible spacer between the heteroaromatic and anhydropyranose cores have been designed and synthesized following an hetero Michael // 1,3-dipolar cycloaddition path. The use of a design of experiments approach allowed the optimization of the oxa-Michael reaction with propargyl alcohol as nucleophile, a key step for the synthesis of the target compounds. All of the compounds were tested for their anticancer activity on MDA-MB-231 cells, featuring mutant p53.

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The Scientific Advisory Board (SAB) of the Organisation for the Prohibition of Chemical Weapons (OPCW) has provided advice on assistance and protection in relation to the Chemical Weapons Convention. In this, the first of several papers describing the SAB's work on this topic, we describe advice given in response to questions from the OPCW Director-General in 2013 and 2014 on the status of available medical countermeasures and treatments to organophosphorus nerve agents. This paper provides the evidence base for this advice which recommended to the OPCW pretreatments, emergency care, and long-term treatments that were available at the time of the request for this class of chemical warfare agent (CWA).

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Compounds that cause powerful sensory irritation to humans were reviewed by the Scientific Advisory Board (SAB) of the Organisation for the Prohibition of Chemical Weapons (OPCW) in response to requests in 2014 and 2017 by the OPCW Director-General to advise which riot control agents (RCAs) might be subject to declaration under the Chemical Weapons Convention (the "Convention"). The chemical and toxicological properties of 60 chemicals identified from a survey by the OPCW of RCAs that had been researched or were available for purchase, and additional chemicals recognised by the SAB as having potential RCA applications, were considered. Only 17 of the 60 chemicals met the definition of a RCA under the Convention.

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The Scientific Advisory Board (SAB) of the Organisation for the Prohibition of Chemical Weapons (OPCW) has provided advice in relation to the Chemical Weapons Convention on assistance and protection. We present the SAB's response to a request from the OPCW Director-General in 2014 for information on the best practices for preventing and treating the health effects from acute, prolonged, and repeated organophosphorus nerve agent (NA) exposure. The report summarises pre- and post-exposure treatments, and developments in decontaminants and adsorbing materials, that at the time of the advice, were available for NAs.

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The design and synthesis of biomass-derived triazoles and the in vitro evaluation as potential anticancer agents are described. The discovery of base-catalyzed retro-aza-Michael//aza-Michael isomerizations allowed the exploration of the chemical space by affording novel types of triazoles, difficult to obtain otherwise. Following this strategy, 2,4-disubstituted 1,2,3-triazoles could be efficiently obtained from the corresponding 1,4-disubstituted analogues.

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The assignment of the relative configuration of spiroepoxides or related quaternary carbon-containing oxiranes can be troublesome and difficult to achieve. The use of GIAO NMR shift calculations can provide helpful assistance in challenging cases of structural elucidation. In this regard, the DP4 probability is one of the most popular methods to be employed when only one set of experimental data is available, though modest results were obtained when dealing with spiroepoxides.

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The 1,3-dipolar cycloaddition reactions of azomethine ylides is one of the preferred methods for the synthesis of polysubstituted pyrrolidines. The use of chiral dipolarophiles derived from carbohydrates yields enantiomerically pure pyrrolidines, usually in good to excellent endo selectivities, along with other minor stereoisomers. Recently, we found an unusual isomerization event that allowed the isolation of useful pyrrolidines with relative stereochemistries difficult to obtain otherwise.

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Chiral acrylic esters derived from biomass were developed as models to have a better insight in the aryl-vinyl π-stacking interactions. Quantum chemical calculations, NMR studies and experimental evidences demonstrated the presence of equilibriums of at least four different conformations: π-stacked and face-to-edge, each of them in an s-cis/s-trans conformation. The results show that the stabilization produced by the π-π interaction makes the π-stacked conformation predominant in solution and this stabilization is slightly affected by the electron density of the aromatic counterpart.

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An efficient and straightforward synthesis of a novel 3-thiomannoside derivative (1,2,4,6-tetra-O-acetyl-3-S-acetyl-3-thio-β-d-mannopyranoside) was developed starting from levoglucosenone. A xanthate-thiocarbonate exchange under acidic conditions was the key step for the new C-S bond. The product was obtained enantiospecifically in very good overall yield.

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An efficient organocatalyst for iminium-ion based asymmetric Diels-Alder (DA) reactions has been rationally designed. The most influential structure-activity relationships were determined experimentally, while DFT calculations and NMR studies provided further mechanistic insight. This knowledge guided an in silico screening of 62 different catalysts using an ONIOM(B3LYP/6-31G*:AM1) transition-state modeling, which showed good correlation between theory and experiment.

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Article Synopsis
  • A new method for creating chiral dioxa-caged compounds from levoglucosenone is introduced, using a 3-step cationic cyclization process.
  • High yields and selectivities were achieved with the help of Montmorillonite K-10 as a catalyst.
  • The research also explores K-10's effectiveness in rearrangements to produce pyran-3-ones, revealing notable reactivity differences in similar alcohols, which were analyzed using DFT calculations.
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Zingerone (1) and both chiral forms of zingerol (2) were obtained from dehydrozingerone (3) by biotransformation with filamentous fungi. The bioconversion of 3 with A. fumigatus, G.

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Tri-O-acetyl-D-allal has been enantiospecifically synthesized in six steps from levoglucosenone in 55% overall yield. A key step in the synthesis is the anhydro bridge ring-opening with concomitant formation of a 1,3-oxathiolane-2-thione ring.

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Cellulose-derived chiral pyrrolidines were synthesized in excellent yields, regioselectivities, and stereoselectivities via a 1,3-dipolar cycloaddition reaction between levoglucosenone and azomethine ylides. An unprecedented isomerization event led to a new family of pyrrolidines with an unusual relative stereochemistry. Preliminary results showed that these compounds are promising organocatalysts for iminium ion-based asymmetric Diels-Alder reactions.

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The Diels-Alder reaction of a pyranose-derived nitroalkene 1 with cyclopentadiene is described, and the unexpected facial selectivity of the cycloaddition is analyzed by a computational study.

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Detailed quantum chemical calculations, experimental evidence, and NMR data rationalize the participation of pi-stacking interaction in the highly asymmetric Diels-Alder reaction using levoglucosenone derived internal chiral auxiliaries, including the appealing effect of inversion of the enantioselectivity by coordination of the substrate with Et 2AlCl.

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The cycloaddition reactions of 9-substituted anthracenes and levoglucosenone were investigated under microwave irradiation and conventional heating conditions. Considering time, yields, and regioselectivity, microwave technology has proven to be an ideal tool to achieve this chemical transformation. [reaction: see text].

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[reaction: see text] A new chiral auxiliary derived from levoglucosenone is reported. The compound is obtained by a cycloaddition reaction with 9-methoxy methylanthracene followed by a diastereoselective reduction of the C-2 keto function. The auxiliary has been used as a chiral template in an asymmetric Diels-Alder reaction of the corresponding acrylic ester derivative with cyclopentadiene.

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The synthesis of the title compound was achieved in seven steps and 61% overall yield from methyl alpha-D-glucopyranoside.

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The oxirane ring-opening of an anhydro sugar with diethylaluminum cyanide (Et(2)AlCN) is a direct approach for obtaining a cyano derivative. Methyl 2,3-anhydro-4,6-O-benzylidene-alpha-D-allopyranoside showed anomalous chemical behavior when treated with Et(2)AlCN. The reaction afforded the corresponding beta-cyanohydrin as the minor component from a mixture of compounds resulting from the benzylidene acetal ring-opening caused by the attack of ethyl or cyano groups.

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