
Esther LeteUniversity of the Basque Country | UPV/EHU · Organic Chemistry II
Esther Lete
Prof. Dr.
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Publications (171)
The enantioselective Brønsted acid-catalyzed α-amidoalkylation reaction is a useful procedure is for the production of new drugs and natural products. In this context, Chiral Phosphoric Acid (CPA) catalysts are versatile catalysts for this type of reactions. The selection and design of new CPA catalysts for different enantioselective reactions has...
The Cp*Co(III) C−H allylation of (hetero)arenes with allyl aryl ethers has been developed using an amide as directing group (24 examples). DFT calculations have shed light on the mechanistic course and reactivity pattern, showing that strong electron releasing groups favour the reaction by reducing the activation barrier of the rate‐determining C−H...
The enantioselective Brønsted acid-catalyzed α-amidoalkylation reaction is a useful procedure is for the production of new drugs and natural products. In this context, Chiral Phosphoric Acid (CPA) catalysts are versatile catalysts for this type of reactions. The selection and design of new CPA catalysts for different enantioselective reactions has...
In this work, the SOFT.PTML tool has been used to pre-process a ChEMBL dataset of pre-clinical assays of antileishmanial compound candidates. A comparative study of different ML algorithms, such as logistic regression (LOGR), support vector machine (SVM), and random forests (RF), has shown that the IFPTML-LOGR model presents excellent values of spe...
The palladium-catalyzed selective C–H alkenylation reaction has been established as a central synthetic transformation to enable the construction of carbon–carbon bonds in an efficient, atom-economical, and environmentally friendly way. It provides a powerful alternative to classical cross-coupling reactions for the construction of conjugated organ...
The use of MW allows the efficient palladium(II)-catalysed C-3 acylation of thiophenes with aldehydes via C(sp2)-H activation for the synthesis of (cyclo)alkyl/aryl thienyl ketones (43 examples). Compared to standard thermal conditions, the use of MW reduces the reaction time (15 to 30 min vs. 1 to 3 hours), leading to improved yields of the ketone...
Highly substituted coumarins, privileged and versatile scaffolds for bioactive natural products and fluorescence imaging, are obtained via a Pd(II)-catalyzed direct C–H alkenylation reaction (Fujiwara–Moritani reaction), which has emerged as a powerful tool for the construction and functionalization of heterocyclic compounds because of its chemical...
The development of new molecules for the treatment of Leishmaniasis, a neglected parasitic disease, is urgent as current anti-leishmanial therapeutics are hampered by drug toxicity and resistance. The pyrrolo[1,2-b]isoquinoline core was selected as starting point, and palladium-catalyzed Heck-initiated cascade reactions were developed for the synth...
The developing of antibacterial resistance is becoming in crisis. In this sense, natural products play a fundamental role in the discovery of antibacterial agents with diverse mechanisms of action. Phytochemical investigation of Cissus incisa leaves led to isolation and characterization of the ceramides mixture (1): (8E)-2-(tritriacont-9-enoyl amin...
Dear colleagues worldwide, we are glad to invite you to MOL2NET-07, International Conference on Multidisciplinary Sciences, ISSN: 2624-5078, MDPI SciForum, Basel, Switzerland, 2021. MOL2NET is an international conference formed by an association of several inter-university tansatlantic workshops or sessions. These workshops are chaired by one North...
The use of earth-abundant first-row transition metals, such as cobalt, in C-H activation reactions for the construction and functionalization of a wide variety of structures has become a central topic in synthetic chemistry over the last few years. In this context, the emergence of cobalt catalysts bearing pentamethylcyclopentadienyl ligands (Cp*)...
Guanidines have received great attention due to their application as superbasic proton sponges and organocatalysts, as well as excellent N-donor ligands able to coordinate with different metals. The introduction of different substituents can modulate the basicity/nucleophilicity of the guanidines, their coordination ability, and thus, the electroni...
The first example of Cp*Co(III)-catalyzed intramolecular hydroarylation of allyl aryl ethers using an amide directing group for the preparation of 3,3-disubstituted dihydrobenzofurans in high yields is described. The reaction of the unactivated alkene is completely selective for the formation of the quaternary center, allowing different substitutio...
The Front Cover shows, inspired by the famous scene of the classical movie “Modern Times”, a “robotical” Palladium that selectively assembles the pyrrole ring, which incorporates the directing group and the acyl radical, in a modern approach to acylation reactions. The authors acknowledge the artist, Patricia Fañanás (2nd year BA in digital art stu...
Di(hetero)aryl ketones are important motifs present in natural products, pharmaceuticals or agrochemicals. In recent years, Pd(II)-catalyzed acylation of (hetero)arenes in the presence of an oxidant has emerged as a catalytic alternative to classical acylation methods, reducing the production of toxic metal waste. Different directing groups and acy...
Welcome From Chairs Dear colleagues worldwide, we are glad to invite you to MOL2NET-05, International Conference on Multidisciplinary Sciences, ISSN: 2624-5078, MDPI SciForum, Basel, Switzerland, 2019. MOL2NET is a year-round conference series with multiple associated workshops worldwide running and open to submissions almost all the year, please r...
Quinoline and quinolone cores are present in a wide variety of pharmaceuticals, agrochemicals and materials, as well in ligands/catalysts in asymmetric synthesis. Transition-metal catalysed based approaches have played a pivotal role in the development of the catalytic methods for their synthesis. This review presents recent developments on palladi...
The PdII‐catalyzed C‐2 acylation of pyrrole with aldehydes in the presence of TBHP as oxidant has been studied for the synthesis of di(hetero)aryl ketones. The use of 2‐pyrimidine as directing group leads to 2‐acylpyrroles in moderate to good yields, although 2,5‐diacylpyrroles are obtained as by products. This side‐reaction could be avoided using...
A protocol for the Pd(II)-catalyzed C-H alkenylation reaction of substituted N-allylanilines via an unusual 6-endo process has been developed. A DFT study of the mechanistic pathway has shown that the coordination of the remote protecting group to the palladium center is determinant for the control of the regioselectivity in favor of the 6-endo pro...
Background
Cheminformatics models are able to predict different outputs (activity, property, chemical reactivity) in single molecules or complex molecular systems (catalyzed organic synthesis, metabolic reactions, nanoparticles, etc.).
Objective
Cheminformatics prediction of complex catalytic enantioselective reactions is a major goal in organic s...
G protein-coupled receptors (GPCRs), also known as 7-transmembrane receptors, are the single largest class of drug targets. Consequently, a large amount of preclinical assays having GPCRs as molecular targets has been released to public sources like the Chemical European Molecular Biology Laboratory (ChEMBL) database. This data is also very complex...
USA-Europe Data Analysis Training School (USEDAT) is a Multi-center Trans-Atlantic initiative offering hands-on training focused in both Introduction to Experimental Data Recording (NMR, MS, IR, 2DGE, EEG, etc.) and/or posterior Computational Data Analysis (Machine Learning, Complex Networks, etc.). We made emphasis on applications in for Cheminfor...
A convergent route to pyrrolo[1,2-b]isoquinolines with a quaternary center at C-10 has been developed, that implies a sequential Pd(0)-catalyzed carbopalladation followed by cross-coupling reaction with boronic acids. The adequate catalytic system and experimental conditions, with and without the use of phosphane ligands, have been selected to cont...
Predicting the activity of new chemical compounds over pathogenic microorganisms with different Metabolic Reaction Networks (MRNs) is an important goal due to the different susceptibility to antibiotics. ChEMBL database contains >160 000 outcomes of preclinical assays of antimicrobial activity for 55931 compounds with >365 parameters of activity (M...
Conference: Proceedings of the conference MOL2NET International Conference on Multidisciplinary Sciences (4th edition), 2018 is part of a year-round worldwide conference series hosted by MDPI Sciforum, Basel, Switzerland. This conference series has had organized more than 20 associated workshop series in universities worldwide: USA, France, Portuga...
The intramolecular Pd(II)-catalyzed alkenylation of aryl homoallyl ethers constitutes a mild, versatile and efficient procedure for the synthesis of highly and diversely substituted chromanes and 2H-chromenes. The use of p-TsOH as additive allows more efficient reactions that could be carried out a room temperature in most cases. The procedure has...
Machine Learning (ML) algorithms are gaining importance in the processing of chemical information and modelling of chemical reactivity problems. In this work, we have developed a PTML model combining Perturbation-Theory (PT) and ML algorithms for predicting the yield of a given reaction. For this purpose, we have selected Parham cyclization, which...
We are glad to invite all colleagues worldwide to participate on a new edition of this International Conference Series. The official title of this conference series is MOL2NET International Conference Series on Multidisciplinary Sciences. MOL2NET (the conference running title) is the acronym of the lemma of the conference: From Molecules to Network...
Proceedings of the conference MOL2NET International Conference on Multidisciplinary Sciences (3rd edition), 2017. Year-Round conference series hosted by MDPI Sciforum, Basel, Switzerland. These conferences have more than 10 associated workshop series in universities of USA, Spain, China, Chile, Brazil, etc. These workshop series run in person and/o...
Proceedings of MOL2NET International Conference on Multidisciplinary Sciences (2nd edition), 2016. Year-Round conferences series hosted by MDPI Sciforum, Basel, Switzerland with > 10 associated in person workshops in USA, Spain, China, Chile, Brazil, etc. Some of the workshops are SRI-08 St Thomas University (STU)- Miami Dade College (MDC), Miami,...
Palladium-catalyzed dehydrogenative coupling is an efficient synthetic strategy for the construction of quinoline scaffolds, a privileged structure and prevalent motif in many natural and biologically active products, in particular in marine alkaloids. Thus, quinolines and 1,2-dihydroquinolines can be selectively obtained in moderate-to-good yields...
An organolithium addition–intramolecular α-amidoalkylation sequence on N-phenethylimides has been developed for the synthesis of fused tetrahydroisoquinoline systems using 1,1′-bi-2-naphthol (binol)-derived Brønsted acids. This transformation is the first in which activated benzene derivatives are used as internal nucleophiles, instead of electron-...
Heteroaryllithiums, obtained via MesLi mediated halogen- lithium exchange, undergo intramolecular addition onto acrylamide and acrylate moieties. Both electron rich (thiophenyl) and electron deficient (pyridinyl, quinolinyl) heteroaromatic halides can be used for the formation of six- and seven membered rings, providing an efficient route to fused...
CONFERENCE SERIES CALL FOR PAPERS
We are glad to invite all colleagues worldwide to participate on the MOL2NET International Conference Series on Multidisciplinary Sciences. MOL2NET (the conference running title) is the acronym of the lemma of the conference: From Molecules to Networks. This running title is inspired by the possibility of multidis...
Enamides with a free NH group have been evaluated as nucleophiles in chiral Brønsted acid-catalyzed enantioselective α-amidoalkylation reactions of bicyclic hydroxylactams for the generation of quaternary stereocenters. A quantitative structure–reactivity relationship (QSRR) method has been developed to find a useful tool to rationalize the enantio...
Supplementary
Asymmetric Mizoroki-Heck reaction is one of most important palladium(0)-catalyzed C-C bond-forming reactions, which has allowed the preparation of optically active molecules with tertiary and quaternary stereocenters. In particular, Heck-Heck cascade reactions are a powerful synthetic strategy for rapidly increasing structural and stereochemical co...
Different 2-alkenyl-substituted pyrroles and pyrrolidines are investigated as cyclization precursors: Pd sources, ligands (chiral and achiral), bases and solvents are tested to produce an optimal result concerning the required stereocenters.
Parham reaction is a very important route for the synthesis of heterocycle compounds using organolithium reagents in the presence of Halogens and internal electrophiles. In this paper we collected a dataset of >100 reactions for many substrates and internal electrophiles with a wide range of yield of reaction (0 – 99%). The reactions have been carr...
Enantioselective intramolecular Heck–Heck cascade reactions have emerged as an excellent tool for the construction of polycyclic frameworks, such as lycorane alkaloids, xestoquinone and analogues. However, it is particularly difficult to rationalize the effect of simultaneous changes in both the structure of many molecular entities and experimental...
The generation of quaternary and tertiary stereocentres at C-10 of the pyrroloisoquinoline skeleton through intramolecular Mizoroki-Heck reactions of 2-alkenyl-substituted pyrroles and pyrrolidines has been studied. The cyclizations proceeded in moderate to good yields (up to 81 %), but with low enantioselectivity when chiral phosphanes such as (R)...
In the last years, the Palladium-catalyzed direct alkenylation of Csp²-H bonds, an oxidative variant of the Heck reaction known as Fujiwara-Moritani reaction, has emerged as an efficient, atom-economical, and environmentally friendly synthetic tool for the preparation of highly functionalized aromatic molecules. In connection with our work in catal...
The a-amidoalkylation reaction of aromatic systems using N-acyliminium ions as electrophiles is one of the most attractive methods for C-C bond formation in heterocyclic chemistry and has found widespread application in natural products synthesis.[1] A significant progress in the application of enantioselective versions of a-amidoalkylation reactio...
(Pyrrolo[1,2-a]benzazepinyl)acetamides, obtained through carbolithiation reactions, have been used as intermediates in the access to Apoerysopine skeleton. Derivatization implies reduction to the correponding aldehyde using the Snieckus procedure for in situ generation of the Schwartz reagent, followed by Wittig reaction and intramolecular Pd(II)-c...
PT-QSRR models are Quantitative Structure-Reactivity Relationship (QSRR) models based on Perturbation Theory (PT) that may be useful for multi-objective optimization in organic synthesis. In this communication, we summarize some of the more important results and conclusions obtained in our previous research / review paper about PT-QSRR models publi...
The diastereoselective Mizoroki-Heck reaction of N-benzylpyrrolidines that incorporate a protected allylic alcohol moiety allows the synthesis of enantiomerically pure pyrrolo[1,2-b]isoquinolines, generating a tertiary stereocenter. The best results were obtained with the use of bulky phosphanes, as P(o-Tol)3. When a good leaving group, such as piv...
Mizoroki-Heck reaction constitutes an effective method for the formation of quaternary stereocenters. This reaction has been applied to functionalized 2-alkenylpyrroles as substrates in which the b-elimination is blocked by a methyl substituent. 10,10-Disubstituted pyrrolo[1,2-b]isoquinolines can be obtained using different palladium catalysts and...
A rapid and efficient access to a wide variety of enantiomerically enriched C‐11b substituted lycorane analogues can be achieved via a catalytic asymmetric Heck–Heck 6‐ exo /6‐ endo cascade reaction in the presence of ( R )‐BINAP.
magnified image
Highly substituted quinolones are obtained through an efficient and atom economical procedure that involves two consecutive palladium(II)‐catalyzed CH alkenylation reactions. A selective 6‐ endo intramolecular CH alkenylation leads to 4‐substituted quinolones that have been further functionalized at C‐3 through a second intermolecular CH alkenyl...
The study of quantitative structure-property relationships (QSPR) is important to study complex networks of chemical reactions in drug synthesis or metabolism or drug-target interactions networks. A difficult but also possible goal is the prediction of drug absorption, distribution, metabolism, and excretion (ADME) process with a single QSPR model....
Cyclization of aryllithiums obtained by iodine-lithium exchange reaction on N-alkenyl 2-iodoanilines allows the synthesis of 4- and 2,4-substituted tetrahydroquinolines. However, the alkene has to be substituted with a stabilizing group for the resulting organolithium to favor the intramolecular carbolithiation. When (-)-sparteine (4) or (+)-sparte...
The intramolecular palladium‐catalyzed reaction of N ‐(iodoarylalkyl)pyrroles can be applied for the selective synthesis of medium‐sized rings by choosing the appropriate catalytic systems to direct the reaction to the alkene or to the pyrrole nucleus. These reactions can also be extended to the corresponding heteroaryl halides. Thus, reaction cond...
The allylmagnesium chloride addition/RCM sequence on N-alkenyl-substituted imides provides a mild access to indolizinone and pyrroloazepinone derivatives with the α-hydroxy-γ-lactam framework. The procedure can be applied to the asymmetric synthesis of this type of derivatives, by employing a 2-exo-hydroxy-10-bornylsulfinyl group as a chiral auxili...
Carbon-nitrogen bond forming reactions oriented to the synthesis of 2-amino-imidazolidines and imidazoles have been investigated. The C-2 amination of imidazolidinones, via the corresponding 2-chlorodihydroimidazoles, led to 2-benzylaminodihydroimidazole or bis(dihydroimidazole) amino derivatives by choosing the adequate experimental conditions. On...
We develop a new QSPR-Perturbation theory model for Synthetic Pathways involving Assymetric Catalysis of Intra-molecular Carbolithiations. In doing so, we used calculated spectral moments of markov electron delocalization matrix for all molecules involved in the reactions. These descriptors and physical variables (temperature etc.) were used to cal...
In general perturbation methods starts with a known exact solution of a problem and add "small" variation terms in order to approach to a solution for a related problem without known exact solution. Perturbation theory has been widely used in almost all areas of science. Bhor's quantum model, Heisenberg's matrix mechanincs, Feyman diagrams, and Poi...
The Mizoroki–Heck reaction of N-alkenyl-substituted 2-haloanilines is an effective protocol for the synthesis of substituted 4-alkylidene-tetrahydroquinoline derivatives, avoiding isomerization and oxidation. When non-substituted alkenes are used, the regioselectivity of the reaction can be directed towards the formation of an exocyclic or endocycl...
Reducing costs in terms of time, animal sacrifice, and material resources with computational methods has become a promising goal in Medicinal, Biological, Physical and Organic Chemistry. There are many computational techniques that can be used in this sense. In any case, almost all these methods focus on few fundamental aspects including: type (1)...
Mesityllithium (MesLi) was found to be superior to butyllithium for the formation of aryllithium intermediates by iodine–lithium exchange. Subsequent intramolecular carbolithiation of the 2-alkenyl-substituted ortho-lithiated N-benzylpyrroles proceeded efficiently when the alkene was substituted with an electron-withdrawing group. The procedure is...
In this review we summarize recent developments in inter- and intramolecular enantioselective carbolithiation reactions carried out in the presence of a chiral ligand for lithium, such as (-)-sparteine, to promote facial selection on a C=C bond. This is an attractive approach for the construction of new carbon-carbon bonds in an asymmetric fashion,...
BINOL-derived chiral Brønsted acids are capable of carrying out the intramolecular α-amidoalkylation of a tertiary N-acyliminium ions when a methoxylated benzene ring is used as internal π nucleophile. The reaction can be applied to the synthesis of pyrrolo[2,1-a]isoquinolines and use of the sterically congested acid 3e is determinant to obtain goo...
The Parham cyclization-intermolecular α-amidoalkylation sequence results in the facile enantioselective synthesis of 12b-substituted isoindoloisoquinolines (ee up to 95%) using BINOL-derived Brønsted acids. α-Amidoalkylation of indole occurs through the formation of a chiral conjugate base/bicyclic quaternary N-acyliminium ion pair.
The intramolecular α-amidoalkylation reactions of aromatic and heteroaromatic ring systems constitute a versatile approach for the synthesis of nitrogen heterocyles in a diastereoselective or enantioselective fashion. On the other hand, the intramolecular reactions of aryllithium compounds have also been extensively used in the synthesis of carbocy...
The intramolecular carbolithiation of alkenes and alkynes has become an interesting approach for the synthesis of functionalized carbocyclic and heterocyclic systems due to the high regio- and stereoselectivity when a carbon-carbon bond is formed and to the possibility of trapping the resulting cyclized organolithium with various electrophiles to i...
In this chapter, we propose the study of multiple systems using node centrality or connectedness information measures derived from a Graph or Complex Network. The information is quantified in terms of the Entropy centrality k
C
θ(j) of the jth parts or states (nodes) of a Markov Chain associated with the system, represented by a network graph. The...
Carbolithiation reactions of 2-alkenyl-substituted pyrrolidines have been studied. An electron-withdrawing group in the alkene (R = CONEt2) is required for the 6-exo-trig cyclization to afford hexahydropyrrolo[1,2-b]isoquinolines. Alternatively, the cyclization of the unactivated alkene can be performed under Heck conditions.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A regioselective synthesis of unsymmetrically substituted deoxybenzoins via α-aminonitriles, establishing the advantage of the use of N,N-dimethylaminonitriles over the corresponding N,N-diethylamino derivatives, is reported.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
α-Hydroxylactams, derived from organolithium addition to an enantiomerically pure N-phenethylnorborn-5-en-endo-2,3-dicarboxyimide with a 2-exo-hydroxy-10-bornylsulfinyl group as chiral auxiliary, undergo efficient and highly diastereoselective N-acyliminium ion cyclization. Subsequent removal of the auxiliary and retro-Diels-Alder reaction lead to...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
7 The8,3′,4′-tetramethoxyisoflavone 2 was synthesized and its structure confirmed by X-ray crystallographic analysis. Pharmacological screening was carried out with this compound in order to assess its pharmacological profile. Isoflavone 2 possessed antiinflamatory activity in the carrageenan oedema test, with a dose-effect relationship comparable...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Diastereodivergent approaches to thiazolo[4,3-a]isoquinoline systems are described. The sequence reduction - N-acyliminium cyclization of 1- substituted N-phenethylthiazolidinediones afforded stereoselectively the 1,10b-cis derivatives. Alternatively, the tandem Parham cyclization - hydroxyl reduction on the corresponding iodinated thiazolidinedion...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.