19 results on '"M. Luísa C. Vale"'
Search Results
2. Methyl 2-diphenylphosphoryloxy-2-azabicyclo[2.2.1]hept-5-ene-3-exo-carboxylate
- Author
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Carlos A. D. Sousa, M. Luísa C. Vale, Xerardo Garcia-Mera, and José E. Rodríguez-Borges
- Subjects
Crystallography ,QD901-999 - Abstract
In the title compound, C20H20NO4P, the dihedral angle between the phenyl rings is 68.52 (7)°. In the crystal structure, the molecules are linked by a weak C—H...π(arene) interaction along [010] involving the phenyl CH group and the phenyl rings. There are no further significant intermolecular interactions.
- Published
- 2009
- Full Text
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3. Surface charge tunable catanionic vesicles based on serine-derived surfactants as efficient nanocarriers for the delivery of the anticancer drug doxorubicin
- Author
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Eduardo F. Marques, Raquel C. F. Gonçalves Lopes, M. Luísa C. Vale, Ana Rita Faria, Jana B. Nieder, and Oscar F. Silvestre
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Cell Survival ,Surface Properties ,Antineoplastic Agents ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Flow cytometry ,Surface-Active Agents ,Pulmonary surfactant ,Cations ,Serine ,medicine ,Humans ,General Materials Science ,Doxorubicin ,Surface charge ,A549 cell ,Drug Carriers ,Microscopy, Confocal ,medicine.diagnostic_test ,Chemistry ,Vesicle ,Cationic polymerization ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,A549 Cells ,Biophysics ,Nanocarriers ,0210 nano-technology ,medicine.drug - Abstract
Self-assembled vesicles composed of amino acid-based cationic/anionic surfactant mixtures show promise as novel effective drug nanocarriers. Here, we report the in vitro performance of vesicles based on cationic (16Ser) and anionic (8-8Ser) serine-based surfactants using a cancer cell model for the delivery of the anticancer drug doxorubicin (DOX). This catanionic mixture yields both negatively (0.20 in the cationic surfactant molar fraction, x16Ser) and positively (x16Ser = 0.58) charged vesicles, hence providing a surface charge tunable system. Low toxicity is confirmed for concentration ranges below 32 μM in both formulations. DOX is successfully encapsulated in the vesicles, resulting in a surface charge switch to negative for the (0.58) system, making both (0.20) and (0.58) DOX-loaded vesicles highly interesting for systemic administration. High uptake by cells was demonstrated using flow cytometry and confocal microscopy. Drug accumulation results in an increase of cell uptake up to 250% and 200% for the (0.20) and (0.58) vesicles, respectively, compared to free DOX and with localizations near the nuclear regions in the cells. The in vitro cytotoxicity studies show that DOX-loaded vesicles induce cell death, confirming the therapeutic potential of the formulations. Furthermore, the efficient accumulation of the drug inside the cell compartments harbors the potential for optimization strategies including phased delivery for prolonged treatment periods or even on-demand release.
- Published
- 2019
4. Effective cytocompatible nanovectors based on serine-derived gemini surfactants and monoolein for small interfering RNA delivery
- Author
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Andreia C. Gomes, Catarina Costa, Eduardo F. Marques, Isabel S. Oliveira, Cláudia Botelho, Sandra G. Silva, M. Luísa C. Vale, João P. Silva, Maria Elisabete C.D. Real Oliveira, and Universidade do Minho
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Small interfering RNA ,02 engineering and technology ,Transfection ,010402 general chemistry ,01 natural sciences ,lipoplex properties ,Glycerides ,monoolein helper lipid ,Biomaterials ,Serine ,serine ,Surface-Active Agents ,Colloid and Surface Chemistry ,siRNA-delivery ,RNA interference ,Gene silencing ,RNA, Small Interfering ,transfection efficiency ,chemistry.chemical_classification ,gemini surfactant ,Liposome ,Science & Technology ,Chemistry ,021001 nanoscience & nanotechnology ,Combinatorial chemistry ,0104 chemical sciences ,3. Good health ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amino acid ,Nucleic acid ,0210 nano-technology - Abstract
Supplementary data to this article can be found online athttps://doi.org/10.1016/j.jcis.2020.09.077., Non-viral gene therapy based on gene silencing with small interfering RNA (siRNA) has attracted great interest over recent years. Among various types of cationic complexation agents, amino acid-based surfactants have been recently explored for nucleic acid delivery due to their low toxicity and high biocompatibility. Monoolein (MO), in turn, has been used as helper lipid in liposomal systems due to its ability to form inverted nonbilayer structures that enhance fusogenicity, thus contributing to higher transfection efficiency. In this work, we focused on the development of nanovectors for siRNA delivery based on three gemini amino acid-based surfactants derived from serine (12Ser)2N12, amine derivative; (12Ser)2COO12, ester derivative; and (12Ser)2CON12, amide derivative individually combined with MO as helper lipid. The inclusion of MO in the cationic surfactant system influences the morphology and size of the mixed aggregates. Furthermore, the gemini surfactant:MO systems showed the ability to efficiently complex siRNA, forming stable lipoplexes, in some cases clearly depending on the MO content, without inducing significant levels of cytotoxicity. High levels of gene silencing were achieved in comparison with a commercially available standard indicating that these gemini:MO systems are promising candidates as lipofection vectors for RNA interference (RNAi)-based therapies., The authors acknowledge Fundação para a Ciência e a Tecnolo-gia (FCT) for financial support through projects UIDB/00081/2020 and UIDB/50006/2020. This work was supported by the‘‘Contrato-Programa” UIDB/04050/2020 funded by national fundsthrough the FCT I.P. Dr. Marisa Passos is gratefully acknowledged for help with the statistical analysis of cytotoxicity data. Fundingby the CCDR-N/NORTE2020/Portugal2020 through project DESign-BIOtechHealth (ref. Norte-01-0145-FEDER-000024) is also acknowledged. I. S. Oliveira and S.G. Silva also acknowledge finan-cial support from FCT through PhD grant SFRH/BD/108629/2015 and Individual Call to Scientific Employment Stimulus - CEEC Indi-vidual grant CEECIND/01932/2017, respectively, info:eu-repo/semantics/publishedVersion
- Published
- 2021
5. Supramolecular self-assembly between an amino acid-based surfactant and a sulfonatocalixarene driven by electrostatic interactions
- Author
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Sandra G. Silva, Catarina Costa, Vitor Francisco, Luis García-Río, Eduardo F. Marques, and M. Luísa C. Vale
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Colloid and Surface Chemistry ,Aqueous solution ,Pulmonary surfactant ,Chemistry ,Critical micelle concentration ,Amphiphile ,Calixarene ,Polymer chemistry ,Supramolecular chemistry ,Cationic polymerization ,Organic chemistry ,Self-assembly - Abstract
Complex self-assembled structures can be built up in aqueous media by making use of non-covalent interactions between small organic molecules and conventional amphiphiles. The macrocycle p -sulfonatocalix[4]arene (SC4) is a known receptor for organic ammonium cations in aqueous solution, showing strong binding ability for those guests and selectivity for several amino acids. Previous studies have shown that this type of water-soluble calixarenes are able to modify the aggregation behavior of surfactants. Here, we explore the interactions and morphologies present in mixtures of SC4 and a cationic serine-based surfactant, resorting to surface tension, light microscopy, cryo-scanning electron microscopy and nuclear magnetic resonance studies. Complexation of the amino acid-based surfactant by the calixarene leads initially to mixed micelle formation and a significant lowering of the critical micelle concentration with respect to the neat surfactant even for very low content of SC4 (up to 1.4 mol%). Interestingly, as the SC4 fraction in the system is gradually increased (about 2–6 mol%), highly flexible tubular structures and vesicles are assembled. The observed self-assembly is rationalized in terms of electrostatic complexation between the two co-solutes and the preferred packing of the supramolecular complexes formed.
- Published
- 2015
6. Serine-based gemini surfactants with different spacer linkages: from self-assembly to DNA compaction
- Author
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Eduardo F. Marques, M. Luísa C. Vale, Isabel S. Oliveira, and Sandra G. Silva
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chemistry.chemical_classification ,Chemistry ,Cationic polymerization ,General Chemistry ,Condensed Matter Physics ,DNA condensation ,Micelle ,Fluorescence spectroscopy ,Crystallography ,chemistry.chemical_compound ,Dynamic light scattering ,Amide ,Peptide bond ,Organic chemistry ,Alkyl - Abstract
Cationic gemini surfactants have strong potential as compaction agents of nucleic acids for efficient non-viral gene delivery. In this work, we present the aggregation behavior of three novel cationic serine-based gemini surfactants as well as their ability to compact DNA per se and mixed with a helper lipid, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). All the surfactants have a 12-12-12 configuration, i.e. two main 12-carbon alkyl chains linked to the nitrogen atom of the amino acid residue and a 12 methylene spacer, but they differ in the nature of the spacer linkage: for (12Ser)2N12, an amine bond; for (12Ser)2CON12, an amide bond; and for (12Ser)2COO12, an ester bond. Interestingly, while the amine-based gemini aggregates into micelles, the amide and ester ones spontaneously form vesicles, which denotes a strong influence of the type of linkage on the surfactant packing parameter. The size, ζ-potential and stability of the vesicles have been characterized by light microscopy, cryogenic scanning electron microscopy (cryo-SEM) and dynamic light scattering (DLS). The interaction of the gemini aggregates with DNA at different charge ratios and in the absence and presence of DOPE has been studied by DLS, fluorescence spectroscopy and cryo-SEM. All the compounds are found to efficiently compact DNA (complexation > 90%), but relevant differences are obtained in terms of the size, ζ-potential and stability of the lipoplexes formed. Results are rationalized in terms of headgroup differences and the type of aggregates present prior to DNA condensation.
- Published
- 2014
7. Morphological and Nanomechanical Behavior of Supported Lipid Bilayers on Addition of Cationic Surfactants
- Author
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Marina I. Giannotti, M. Luísa C. Vale, Eduardo F. Marques, Lorena Redondo-Morata, Lia M. C. Lima, and Fausto Sanz
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1,2-Dipalmitoylphosphatidylcholine ,Lipid Bilayers ,Protein reconstitution ,Phospholipid ,Analytical chemistry ,Surface-Active Agents ,chemistry.chemical_compound ,Differential scanning calorimetry ,Phase (matter) ,Serine ,Electrochemistry ,Nanotechnology ,General Materials Science ,Lipid bilayer ,Spectroscopy ,Mechanical Phenomena ,Liposome ,Cetrimonium ,Chemistry ,Temperature ,Cationic polymerization ,Force spectroscopy ,Surfaces and Interfaces ,Condensed Matter Physics ,Chemical engineering ,Liposomes ,Cetrimonium Compounds ,lipids (amino acids, peptides, and proteins) - Abstract
The addition of surfactants to lipid bilayers is important for the modulation of lipid bilayer properties (e.g., in protein reconstitution and development of nonviral gene delivery vehicles) and to provide insight on the properties of natural biomembranes. In this work, the thermal behavior, organization, and nanomechanical stability of model cationic lipid-surfactant bilayers have been investigated. Two different cationic surfactants, hexadecyltrimethylammonium bromide (CTAB) and a novel derivative of the amino acid serine (Ser16TFAc), have been added (up to 50 mol %) to both liposomes and supported lipid bilayers (SLBs) composed by the zwitterionic phospholipid DPPC. The thermal phase behavior of mixed liposomes has been probed by differential scanning calorimetry (DSC), and the morphology and nanomechanical properties of mixed SLBs by atomic force microscopy-based force spectroscopy (AFM-FS). Although DSC thermograms show different results for the two mixed liposomes, when both are deposited on mica substrates similar trends on the morphology and the mechanical response of the lipid-surfactant bilayers are observed. DSC thermograms indicate microdomain formation in both systems, but while CTAB decreases the degree of organization on the liposome bilayer, Ser16TFAc ultimately induces the opposite effect. Regarding the AFM-FS studies, they show that microphase segregation occurs for these systems and that the effect is dependent on the surfactant content. In both SLB systems, different microdomains characterized by their height and breakthrough force Fb are formed. The molecular organization and composition is critically discussed in the light of our experimental results and literature data on similar lipid-surfactant systems.
- Published
- 2013
8. Synthesis of Gemini Surfactants and Evaluation of Their Interfacial and Cytotoxic Properties: Exploring the Multifunctionality of Serine as Headgroup
- Author
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Ana M. Cardoso, Amália S. Jurado, M. Luísa C. Vale, Maria C. Pedroso de Lima, Cláudia Alves, Sandra G. Silva, and Eduardo F. Marques
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chemistry.chemical_classification ,Carboxylic acid ,Organic Chemistry ,Cationic polymerization ,Peptide ,Combinatorial chemistry ,Amino acid ,chemistry.chemical_compound ,Monomer ,chemistry ,Amide ,Molecule ,Organic chemistry ,Physical and Theoretical Chemistry ,Alkyl - Abstract
Two series of novel cationic gemini surfactants based on the amino acid serine have been synthesized. These compounds contain long alkyl chains linked to the nitrogen atoms of the amino acid residues, as well as spacers interconnecting two carboxylic acid groups, through amide or ester bonds. The most efficient synthetic pathway was established; it involves the introduction of the spacers into the N,N-dialkylated monomeric precursors by peptide condensation methods with diamines or diols, with subsequent methylation and deprotection to yield the final target surfactants. The effects of molecular structure, type of spacer linkage, and spacer length on the interfacial and cytotoxic properties of these gemini surfactants are reported and discussed; studies on gemini surfactants with amine linkages and other relevant homologous compounds (conventional bis-quat gemini and monomeric surfactants) are also included. Overall, it is shown that cationic serine-based gemini surfactants have enhanced interfacial properties and low cytotoxicities, offering potential use in technical and biological applications.
- Published
- 2013
9. A route to selective functionalization of polyhydroxypyrrolidines
- Author
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Olga Caamaño, Fabio Rizzo-Aguiar, José E. Rodríguez-Borges, Carlos Sousa, Xerardo García-Mera, and M. Luísa C. Vale
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chemistry.chemical_classification ,Hydroxylation ,chemistry.chemical_compound ,Double bond ,chemistry ,Stereochemistry ,Organic Chemistry ,Drug Discovery ,Surface modification ,Oxidative cleavage ,Biochemistry ,Combinatorial chemistry - Abstract
A route to selective functionalization of polyhydroxypyrrolidines is described. The method is based on orthogonal protection/deprotection along the process of synthesis of the referred pyrrolidines, which consist in hydroxylation of the double bond of 2-azabicyclo[2.2.1]hept-5-enes followed by its oxidative cleavage and in situ reduction of the intermediate dialdehyde. The synthesis of a novel N -hydroxypyrrolidine is also described.
- Published
- 2012
10. 1,3- versus 1,4-[π4+π2] Cycloadditions between methyl glyoxylate oxime and cyclopentadiene or cyclopentene
- Author
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Xerardo García-Mera, Carlos Sousa, M. Luísa C. Vale, and José E. Rodríguez-Borges
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Cyclopentadiene ,Stereochemistry ,Organic Chemistry ,Glyoxylate cycle ,Oxime ,Biochemistry ,Cycloaddition ,Adduct ,chemistry.chemical_compound ,chemistry ,Drug Discovery ,Cyclopentene ,Aza-Diels–Alder reaction ,Octane - Abstract
The acid catalyzed cycloaddition reaction of methyl glyoxylate oxime with cyclopentadiene (CPD) afforded the corresponding aza-Diels–Alder adducts, the endo and exo isomers of (±)-methyl 2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylates, and as the major product a 1,3-cycloadduct, methyl (1RS,4RS,5RS)-(2-oxa-3-azabicyclo[3.3.0]oct-7-ene)-4-carboxylate. The similar reaction using cyclopentene (CP) provided only the 1,3-cycloadduct methyl (1SR,4RS,5SR)-(2-oxa-3-azabicyclo[3.3.0]octane)-4-carboxylate. The influence of various parameters on the reaction outcome was studied and, based on the results obtained, a mechanism for the formation of both 1,3- and 1,4-cycloadducts is proposed. The structure of all adducts was confirmed by NMR spectroscopic data and/or by X-ray crystallography.
- Published
- 2012
11. Structural analysis of three methyl N-phosphorylated 5,6-dihydroxy-2-azabicyclo[2.2.1]heptane-3-carboxylates
- Author
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José E. Rodríguez-Borges, M. Luísa C. Vale, Xerardo García-Mera, and Carlos Sousa
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Inorganic Chemistry ,Hydroxylation ,Heptane ,chemistry.chemical_compound ,chemistry ,Stereochemistry ,Organic Chemistry ,X-ray ,Crystal structure ,Spectroscopy ,Analytical Chemistry - Abstract
Both exo and endo isomers of (±)-methyl N-diphenylphosphoryl-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate and (±)-methyl N-diphenylphosphoryloxy-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate were dihydroxylated with OsO4. The unexpected formation of (±)-methyl 5,6-dihydroxy-N-diphenylphosphoryl-2-azabicyclo[2.2.1]heptane-3-endo-carboxylate from (±)-methyl N-diphenylphosphoryloxy-2-azabicyclo[2.2.1]hept-5-ene-3-endo-carboxylate is discussed based on NMR analyses and experimental observations. The two N-diphenylphosphoryl dihydroxybicycles are analyzed in terms of their crystalline structure by X-ray crystallography.
- Published
- 2012
12. Serine-Based Bis-quat Gemini Surfactants: Synthesis and Micellization Properties
- Author
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M. Luísa C. Vale, Eduardo F. Marques, S. Goreti Silva, and Ricardo M.F. Fernandes
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chemistry.chemical_classification ,Organic Chemistry ,Thermodynamics of micellization ,Cationic polymerization ,Reductive amination ,Micelle ,chemistry.chemical_compound ,Monomer ,chemistry ,Critical micelle concentration ,Organic chemistry ,Amine gas treating ,Physical and Theoretical Chemistry ,Alkyl - Abstract
The synthesis of novel cationic gemini surfactants based on serine, with long lipophilic alkyl chains and a spacer linked to the nitrogen atom of the amino acid residue by amine linkages, is described. The most efficient synthetic pathway involves introduction of the spacer into the monomeric precursors, N-alkyl derivatives, by reductive amination of dialdehydes followed by methylation and deprotection. Characterization of the basic micellization properties of the new compounds was carried out by tensiometry and conductimetry. These surfactants present enhanced interfacial properties compared to the monomeric analogues, and show improved performance, namely lower critical micelle concentration (cmc), lower surface tension at cmc and increased micellar ionization, with respect to conventional bis-quaternary ammonium salts (bis-quats).
- Published
- 2011
13. Highly diastereoselective synthesis of 2-azabicyclo[2.2.1]hept-5-ene derivatives: Bronsted acid catalyzed aza-Diels–Alder reaction between cyclopentadiene and imino-acetates with two chiral auxiliaries
- Author
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Maria J. Alves, Xerardo García-Mera, M. Luísa C. Vale, José E. Rodríguez-Borges, and Universidade do Minho
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Science & Technology ,Cyclopentadiene ,010405 organic chemistry ,Chemistry ,Stereochemistry ,Organic Chemistry ,Absolute configuration ,Asymetric synthesis ,Protonation ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Cycloaddition ,Induction ,0104 chemical sciences ,Adduct ,chemistry.chemical_compound ,Cycloadditions ,Drug Discovery ,Aza-Diels–Alder reaction ,Aza-Diels-Alder reaction ,Brønsted–Lowry acid–base theory ,Chiral auxiliaries ,Ene reaction - Abstract
The cycloaddition between protonated glyoxylate imines possessing two chiral auxiliaries, N-(S)- or N-(R)-1-phenylethyl and (-)-8-phenylmenthyl or (+)-8- phenylneomenthyl, and cyclopentadiene is described. The absolute configuration of all adducts formed was unequivocally assigned through NMR, specific optical rotation and X-ray data of appropriated derivatives. Experimental results confirm the highly exoselectivity for these aza-Diels–Alder reactions, single adducts being obtained from combinations of (8PM)-(R-PEA) and (8PNM)-(S-PEA)., Thanks are due to Fundacao para a Ciencia e Tecnologia (FCT) for financial support given to Faculdade de Ciencias do Porto (project PTDC/QUI/67407/2006) and for financial support through the re-equipment program REDE/1517/RMN/2005.
- Published
- 2011
14. Towards novel efficient monomeric surfactants based on serine, tyrosine and 4-hydroxyproline: synthesis and micellization properties
- Author
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Eduardo F. Marques, S. Goreti Silva, J. Enrique Rodríguez-Borges, and M. Luísa C. Vale
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chemistry.chemical_classification ,Organic Chemistry ,Cationic polymerization ,Biochemistry ,Reductive amination ,Aldehyde ,Chemical synthesis ,Serine ,chemistry ,Drug Discovery ,Organic chemistry ,Amination ,Saponification ,Alkyl - Abstract
The synthesis of some novel monomeric serine- and tyrosine-based cationic and 4-hydroxyproline-based anionic surfactants, having a long lipophilic alkyl chain directly attached to the nitrogen atom of the amino acid, is described. The most efficient synthetic methodologies were established: reductive amination of the corresponding ‘fatty’ aldehydes, followed by methylation and deprotection (serine and tyrosine) to obtain the cationic surfactants; or reductive amination followed by saponification (4-hydroxyproline) to obtain the anionic ones. All the compounds were obtained in good to excellent yields. An assessment of their micellization properties and surface activity by tensiometry showed fairly good performance levels.
- Published
- 2009
15. Acid-catalyzed aza-Diels–Alder versus 1,3-dipolar cycloadditions of methyl glyoxylate oxime with cyclopentadiene
- Author
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Carlos Sousa, Xerardo García-Mera, José E. Rodríguez-Borges, M. Luísa C. Vale, and Jesús Rodríguez-Otero
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Cyclopentadiene ,Stereochemistry ,Organic Chemistry ,Oxime ,Biochemistry ,Cycloaddition ,Adduct ,chemistry.chemical_compound ,chemistry ,Drug Discovery ,1,3-Dipolar cycloaddition ,Aza-Diels–Alder reaction ,Brønsted–Lowry acid–base theory ,Dichloromethane - Abstract
The acid-catalyzed 1,4- and 1,3-cycloadditions between methyl glyoxylate oxime ( 1 ) and cyclopentadiene were investigated using various Lewis and/or Bronsted acids at different temperatures in dichloromethane as solvent. Besides the expected new adducts, (±)-methyl [(3- exo )-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate ( 2 ) and (±)-methyl [(3- endo )-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate ( 3 ), a third adduct, (±)-methyl (1 R ,4 R ,5 R )-(2-oxa-3-azabicyclo[3.3.0]oct-7-ene)-4-carboxylate ( 4 ), whose formation can be explained by a 1,3-dipolar cycloaddition, was obtained. Yields and product ratios were found to be more dependent on the catalyst than on the temperature; these results and the stereochemistry of the adducts, confirmed by spectroscopic data ( 1 H and 13 C NMR) and by X-ray crystallography, were used to analyze and propose a mechanistic explanation for both cycloadditions.
- Published
- 2008
16. Size, charge, and stability of fully serine-based catanionic vesicles: towards versatile biocompatible nanocarriers
- Author
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Eduardo F. Marques, M. Luísa C. Vale, and Sandra G. Silva
- Subjects
Anions ,Biocompatibility ,Chemistry ,Vesicle ,Organic Chemistry ,Nanotechnology ,Biocompatible Materials ,General Chemistry ,Micelle ,Catalysis ,Surface-Active Agents ,Drug Delivery Systems ,Dynamic light scattering ,Chemical engineering ,Microscopy, Electron, Transmission ,Phase (matter) ,Cations ,Amphiphile ,Zeta potential ,Serine ,Self-assembly ,Micelles - Abstract
Vesicles based on mixed cationic and anionic surfactants (catanionic vesicles) offer a number of advantageous colloidal features over conventional lipid-based vesicles, namely spontaneity in formation, long-term stability, and easy modulation of size and charge. If biocompatibility is added through rational design of the chemical components, the potential for biorelated applications further emerges. Here, we report for the first time on two catanionic vesicle systems in which both ionic amphiphiles are derivatized from the same amino acid--serine--with the goal of enhancing aggregate biocompatibility. Phase behavior maps for a mixture with chain length symmetry, 12Ser/12-12Ser, and another with asymmetry, 16Ser/8-8Ser, are presented, for which regions of vesicles, micelles, and coexisting aggregates are identified. For the asymmetric mixture, detailed phase behavior and microstructure characterization have been carried out based on surface tension, light microscopy, cryo-SEM, cryo-TEM, and dynamic light scattering analysis. Vesicles are found with tunable mean size, pH, and zeta potential. Changes in aggregate shape with varying composition and the effect of preparation methods and aging on vesicle features and stability have been investigated in detail. The results are discussed in the light of self-assembly models and related catanionic systems reported before. A versatile system of robust vesicles is thus presented for potential applications.
- Published
- 2014
17. Stereoselective synthesis of polyhydroxylated pyrrolidines: a route to novel 3,5-bis(hydroxymethyl)pyrrolidines from 2-azabicyclo[2.2.1]hept-5-enes
- Author
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Fabio Rizzo Aguiar, M. José Alves, Teresa P. Santos, Xerardo García-Mera, M. Luísa C. Vale, and José E. Rodríguez-Borges
- Subjects
chemistry.chemical_classification ,Cyclopentadiene ,Double bond ,010405 organic chemistry ,Organic Chemistry ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Hydroxylation ,chemistry.chemical_compound ,chemistry ,Drug Discovery ,Glyoxylates ,Organic chemistry ,Stereoselectivity ,Hydroxymethyl ,Oxidative cleavage - Abstract
An efficient preparation of racemic and chiral 2-functionalized-3,5-bis(hydroxymethyl)pyrrolidines is described. The method uses 2-azabicyclo[2.2.1]hept-5-enes, readily obtained from glyoxylates of aliphatic amines and cyclopentadiene, as starting material. The hydroxylation of the double bond followed by the oxidative cleavage of the six-membered ring and in situ reduction of the dialdehyde intermediate gives the title pyrrolidines.
- Published
- 2006
18. Phosphorylation of 2-azabicyclo[2.2.1]hept-5-ene and 2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene systems: synthesis and mechanistic study
- Author
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M. Luísa C. Vale, Xerardo García-Mera, José E. Rodríguez-Borges, Carlos Sousa, and Faculdade de Ciências
- Subjects
Química [Ciências exactas e naturais] ,Chemistry ,Stereochemistry ,General Chemistry ,Nuclear magnetic resonance spectroscopy ,Química ,Mass spectrometry ,Chloride ,Catalysis ,Adduct ,chemistry.chemical_compound ,Chemical sciences ,Chemical sciences [Natural sciences] ,Materials Chemistry ,medicine ,Chlorodiphenylphosphine ,Phosphorylation ,Ene reaction ,medicine.drug - Abstract
The endo and exo isomers of (+/-)-methyl 2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylates and the in situ-prepared endo and exo isomers of (+/-)-methyl 2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate were treated with diphenylphosphinic chloride (OPClPh(2)) and chlorodiphenylphosphine (ClPPh(2)) to afford the corresponding phosphorylated bicycles. The structure of all these compounds was unequivocally determined by NMR spectroscopy and mass spectrometry, and, based on the results obtained, a mechanistic scheme for the phosphorylation reaction of these adducts to afford the corresponding phosphorylbicycles is proposed.
- Published
- 2010
19. Aza-Diels-Alder versus 1,3-Dipolar Cycloadditions of Methyl Glyoxylate Oxime with Cyclopentadiene
- Author
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José E. Rodríguez-Borges, M. Luísa C. Vale, Xerardo García-Mera, Carlos Sousa, and Universidade de Santiago de Compostela. Departamento de Química Orgánica
- Subjects
Cyclopentadiene ,Oxime ,Medicinal chemistry ,Cycloaddition ,Adduct ,chemistry.chemical_compound ,chemistry ,Glyoxylate oxiame ,1,3-dipolar cycloaddition ,1,3-Dipolar cycloaddition ,Aza-Diels–Alder reaction ,Aza-Diels-Alder reaction ,Isoxazolidines ,2-hydroxy-2-azabicyclo[2.2.1]heptenes ,Brønsted–Lowry acid–base theory ,Dichloromethane - Abstract
The 12th International Electronic Conference on Synthetic Organic Chemistry session Computational Chemistry The acid-catalyzed [3+2] and [4+2] cycloadditions between methyl glyoxylate oxime (1) and cyclopentadiene were investigated using various Lewis and/or Bronsted acids at different temperatures in dichloromethane as solvent. Besides the expected new adducts, (±)-methyl [(3-exo)-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate (2) and (±)-methyl [(3-endo)-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate (3) a third addict, (±) methyl (1R,4R,5R)-(2-ox-3-azabicyclo[3.3.0]oct-7-ene)-4-carboxylate (4), whose formation can be explained by a concerted 1,3-dipolar cycloaddition, was obtained. Yields and product ratios were found to be more dependent on the catalyst than on the temperature; these results and the stereochemistry of the adducts, confirmed by spectroscopic data (1H and 13C NMR) and by X-ray cycloadditions This work was supported by Centro de Investigação em Química of University of Porto. The authors thank the Fundação para a Ciência e Tecnologia (FCT) for financial support of this work under project POCTI/QUI/44471/2002 (Pluri-annual and Programmatic Funding) and for the grant to C. A. D. Sousa (SFRH/BD/31526/2006)
- Published
- 2008
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