Publicaciones 2011-2020

@article{RN390,
title = {Blue-Fluorescent Probes for Lipid Droplets Based on Dihydrochromeno-Fused Pyrazolo- and Pyrrolopyridines},
author = { M. Becerra-Ruiz and V. Vargas and P. Jara and C. Tirapegui and C. Carrasco and M. Nunez and N. Lezana and A. Gald\'{a}mez and M. Vilches-Herrera},
url = {/brokenurl#<Go to ISI>://WOS:000444540900018},
doi = {10.1002/ejoc.201701633},
issn = {1434-193x},
year = {2018},
date = {2018-01-01},
journal = {European Journal of Organic Chemistry},
volume = {10.1002/ejoc.201701633},
number = {34},
pages = {4795-4801},
abstract = {Lipid droplets (LDs) have been recognized as highly dynamic cellular organelles involved in important biological functions for the survival of organisms such as supplying food or energy. Nevertheless, lipid storage must be tightly controlled, because both its excess and the inability to store lipids can be detrimental to the organism, resulting in metabolic diseases or multifaceted systemic problems. Visualization and the monitoring of the concentration of LDs is essential to understanding these processes. Commercially available LD dyes, such as Nile Red and boron-dipyrromethene (BODIPY), offer several advantageous characteristics, but can be limiting in multicolor imaging because most ready-made fluorescent reporter constructs fluoresce in the green-to-red region of the visible spectrum. Nile Red emits between green and red, and BODIPY can be photoconverted from green to red fluorescence, limiting its ability to be utilized for time-lapse imaging of living cells. Here, we report the design and synthesis, the photophysical characterization, and biological testing of two easily prepared series of new blue-fluorescing dyes as markers for LDs. Confocal fluorescence microscopy results showed an interesting correlation between the chemical structures of these fluorescent probes and their specific staining patterns. The pyrazole-based compound 11c was found to be a specific dye for LDs, whereas the pyrrole-based compound 10d led to prominent staining of the membranous cell organelles.},
keywords = {derivatives, design, diels-alder dyes, fluorescent fused-ring heterocycles, lipids, nitrogen photophysics, probes, prodrugs, reactions, red solvent, systems},
pubstate = {published},
tppubtype = {article}
}

@article{RN377,
title = {Mechanism for the Snar Reaction of Atrazine with Endogenous Thiols: Experimental and Theoretical Study},
author = { K. Calfuman and S. Gallardo-Fuentes and R. Contreras and R.A. Tapia and P.R. Campodonico},
url = {/brokenurl#<Go to ISI>://WOS:000413526200036},
doi = {10.1039/c7nj02708g},
issn = {1144-0546},
year = {2017},
date = {2017-01-01},
journal = {New Journal of Chemistry},
volume = {41},
number = {21},
pages = {12671-12677},
abstract = {The reaction mechanism in aromatic nucleophilic substitution reactions is discussed using kinetic study complemented with quantum chemical calculations. The model system is the reaction of a series of biothiols toward atrazine (ATZ) in aqueous media. The proposed reaction mechanism discloses a non-catalyzed pathway and the presence of a deprotonated (thiolate) nucleophile in water suggests that the reaction mechanism is borderline between a stepwise route and a concerted process. The full analysis of the potential energy surface reinforces the addition/elimination mechanism. Despite numerous attempts to locate transition structures associated with the leaving group departure, they were unsuccessful, presumably because this step is extremely fast.},
keywords = {aromatic-substitution ions, path protein, reactions, rings, sites},
pubstate = {published},
tppubtype = {article}
}

@article{RN272,
title = {Quantitative Characterization of the Global Philicity Patterns of Common Diene/Dienophile Pairs in Cycloaddition Reactions Ii: The Interacting Pair Model},
author = { C. Perez-Mendez and R. Contreras},
url = {/brokenurl#<Go to ISI>://WOS:000351790700004},
doi = {10.1016/j.tetlet.2015.01.199},
issn = {0040-4039},
year = {2015},
date = {2015-01-01},
journal = {Tetrahedron Letters},
volume = {56},
number = {14},
pages = {1767-1770},
publisher = {2015 Elsevier Ltd.},
abstract = {We present a unified model of electrophilicity and nucleophilicity that considers the electrophile/nucleophile pair in an interacting regime, thereby avoiding the arbitrariness of defining them as the opposite ends of a unique reactivity scale. The model is validated against rate coefficients for the cycloaddition of azomethine ylides towards substituted acetylenes and Michael addition of a series of 1-(X-substituted pheny1)-2-propyn-1-ones towards hydrazine.},
keywords = {amines, charge cycloaddition, diels-alder electronegativity, electrophilicity, hardness, mechanism, michael nucleophilicity, reactions, reactivity},
pubstate = {published},
tppubtype = {article}
}

@article{RN271,
title = {Mechanistic Insights into the Anrorc-Like Rearrangement between Methylhydrazine and 1,2,4-Oxadiazole Derivatives},
author = { S. Gallardo-Fuentes and R. Contreras},
url = {/brokenurl#<Go to ISI>://WOS:000360656100012},
doi = {10.1039/c5ob01300c},
issn = {1477-0520},
year = {2015},
date = {2015-01-01},
journal = {Organic & Biomolecular Chemistry},
volume = {13},
number = {36},
pages = {9439-9444},
abstract = {We herein present the first in-depth theoretical study devoted to elucidate the mechanism of the reaction between 1,2,4-oxadiazole derivatives and methylhydrazine. For this purpose, the reaction between methylhydrazine and some polyfluoroaryl-1,2,4-oxadiazoles has been employed as a model reaction. The analysis of the potential energy surface (PES) indicates that the most favorable path involves an initial amine attack at the C(2') site of the aryl moiety to yield an aryl-hydrazine intermediate whose thermodynamic stability appears as the main determinant of the favored reaction path. Next, the cyclization step leading to a spiro intermediate through a favored 5-exo-trig process appears as the rate determining step. Additionally, this study highlights the relevance of the torsional strain effects on the favored ANRORC pathway. Finally, both the origins of the substituent effects on the regioselectivity patterns as well as the need of using a large excess of nucleophile to afford the favored ANRORC pathway are discussed.},
keywords = {aromatic-substitution density fluorinated functionals, heterocyclic-compounds, hydrazine, indazoles, kinetics nucleophile, organic-chemistry, reactions, reactivities},
pubstate = {published},
tppubtype = {article}
}

@article{RN167,
title = {Specific Nucleophile-Electrophile Interactions in Nucleophilic Aromatic Substitutions},
author = { R. Ormazabal-Toledo and R. Contreras and R.A. Tapia and P.R. Campodonico},
url = {/brokenurl#<Go to ISI>://WOS:000316011300012},
doi = {10.1039/c3ob27450k},
issn = {1477-0520},
year = {2013},
date = {2013-01-01},
journal = {Organic & Biomolecular Chemistry},
volume = {11},
number = {14},
pages = {2302-2309},
abstract = {We herein report results obtained from an integrated experimental and theoretical study on aromatic nucleophilic substitution (SNAr) reactions of a series of amines towards 1-fluoro-2,4-dinitrobenzene in water. Specific nucleophile-electrophile interactions in the title reactions have been kinetically evaluated. The whole series undergoes SNAr reactions where the formation of the Meisenheimer complex is rate determining. Theoretical studies concerning specific interactions are discussed in detail. It is found that H-bonding effects along the intrinsic reaction coordinate profile promote the activation of both the electrophile and the nucleophile. Using these results, it is possible to establish a hierarchy of reactivity that is in agreement with the experimental data. Second order energy perturbation energy analysis highlights the strong interaction between the ortho-nitro group and the acidic hydrogen atom of the amine. The present study strongly suggests that any theoretical analysis must be performed at the activated transition state structure, because the static model developed around the reactant states hides most of the relevant specific interactions that characterize the aromatic substitution process.},
keywords = {base binary catalysis, group, groups, leaving mechanism, mixtures, nitro ortho-para ratio, reactions, secondary-amines, snar solvent},
pubstate = {published},
tppubtype = {article}
}