Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Saudi Pharm J ; 32(3): 101962, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38318318

RESUMO

Background: Tetrazole-based derivatives and their electronic structures have displayed interesting antimicrobial activity. Methods: The tetrazole-based hybrids linked with thiazole, thiophene and thiadiazole ring systems have been synthesized through various chemical reactions. The computational method DFT/B3LYP has been utilized to calculate their electronic properties. The antimicrobial effectiveness was investigated against representative bacterial and fungal strains. Additionally, the synthesized derivatives binding interaction was stimulated by docking program against PDB ID: 4URO as a model of the ATP binding domain of S. aureus DNA Gyrase subunit B. Results: The structures of the synthesized tetrazole-based derivatives were confirmed by IR, NMR, and Mass spectroscopic data. The DFT/B3LYP method showed that the thiadiazole derivatives 9a-c had lower ΔEH-L than the thiophenes 7a-c and thiazoles 5a-c. The hybrids 5b, 5c, and 7b exhibited proper antibacterial activity against Gram's +ve bacterial strains (S. aureus and S. pneumonia), while 9a displayed potent activity towards Gram's -ve bacterial strains (S. typhimurium and E. coli). Meanwhile, derivatives 5a-b, 7a, 7c, and 9c showed good effectiveness towards fungal strain (C. albicans). Conclusion: The study provides valuable tetrazole core-linked heterocyclic rings and opens the door to further research on their electrical characteristics and applications. Tetrazoles and thiazoles have antibacterial properties in pharmacological frameworks, making these hybrids potential lead molecules for drug development. The conclusion summarizes the data and suggests that the synthesized chemicals' interaction with a particular protein domain suggests focused biological activity.

2.
Luminescence ; 38(8): 1440-1448, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37085957

RESUMO

Pentafluoroaryl analogues have been found to exhibit para specific nucleophilic aromatic substitution (SN Ar). Herein, we describe the use of SN Ar chemistry to create luminous perfluorinated symmetrical terphenyls. Both of SN Ar chemistry and copper(I)-catalysed decarboxylative cross-coupling were applied for the synthesis of the perfluorinated symmetrical terphenyls in high yields from the corresponding derivatives of aryl iodide and potassium salt of fluorobenzoate. A series of perfluorinated symmetrical terphenyls with different para alkoxy chains were synthesized. The synthesized perfluorinated terphenyl adducts were confirmed via elemental analysis, Fourier-transform infrared (FTIR), proton (1 H) carbon-13 (13 C) and fluorine-19 (19 F) nuclear magnetic resonance (NMR) spectra. The absorbance and fluorescence spectra showed solvatochromic activities. The new synthesized fluoroterphenyl hybrids were screened against antioxidant inspection over DPPH (2,2-diphenyl-1-picrylhydrazyl) performance, in assessment of vitamin C and butylated hydroxytoluene (BHT) as standard drugs exposed that fluoroterphenyl hybrid covering decyl hydrocarbons exhibited highest effectiveness through half maximal inhibitory concentration (IC50 ) values of 21.74 µg/ml. Additionally, molecular docking procedures of the synthesized fluoroterphenyl hybrids were employed by using protein data bank (PDB ID: 5IKQ). The docking simulation displayed convenient and recognized findings with the antioxidant examination.


Assuntos
Antioxidantes , Cobre , Antioxidantes/química , Simulação de Acoplamento Molecular , Ácido Ascórbico , Espectroscopia de Ressonância Magnética
3.
Molecules ; 28(9)2023 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-37175179

RESUMO

In the present study, we investigated the antiviral activities of 17 flavonoids as natural products. These derivatives were evaluated for their in vitro antiviral activities against HIV and SARS-CoV-2. Their antiviral activity was evaluated for the first time based on POM (Petra/Osiris/Molispiration) theory and docking analysis. POM calculation was used to analyze the atomic charge and geometric characteristics. The side effects, drug similarities, and drug scores were also assumed for the stable structure of each compound. These results correlated with the experimental values. The bioinformatics POM analyses of the relative antiviral activities of these derivatives are reported for the first time.


Assuntos
Antivirais , COVID-19 , Humanos , Antivirais/farmacologia , Antivirais/química , Enzima de Conversão de Angiotensina 2 , Farmacóforo , Flavonoides/farmacologia , SARS-CoV-2 , Computadores , Simulação de Acoplamento Molecular
4.
Molecules ; 26(21)2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34771085

RESUMO

Targeting the EGFR with small-molecule inhibitors is a confirmed valid strategy in cancer therapy. Since the FDA approval of the first EGFR-TKI, erlotinib, great efforts have been devoted to the discovery of new potent inhibitors. Until now, fourteen EGFR small-molecule inhibitors have been globally approved for the treatment of different types of cancers. Although these drugs showed high efficacy in cancer therapy, EGFR mutations have emerged as a big challenge for these drugs. In this review, we focus on the EGFR small-molecule inhibitors that have been approved for clinical uses in cancer therapy. These drugs are classified based on their chemical structures, target kinases, and pharmacological uses. The synthetic routes of these drugs are also discussed. The crystal structures of these drugs with their target kinases are also summarized and their bonding modes and interactions are visualized. Based on their binding interactions with the EGFR, these drugs are also classified into reversible and irreversible inhibitors. The cytotoxicity of these drugs against different types of cancer cell lines is also summarized. In addition, the proposed metabolic pathways and metabolites of the fourteen drugs are discussed, with a primary focus on the active and reactive metabolites. Taken together, this review highlights the syntheses, target kinases, crystal structures, binding interactions, cytotoxicity, and metabolism of the fourteen globally approved EGFR inhibitors. These data should greatly help in the design of new EGFR inhibitors.


Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Animais , Antineoplásicos/uso terapêutico , Ligação Competitiva , Técnicas de Química Sintética , Estudos Clínicos como Assunto , Aprovação de Drogas , Desenvolvimento de Medicamentos , Avaliação Pré-Clínica de Medicamentos , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/química , Receptores ErbB/genética , Receptores ErbB/metabolismo , Humanos , Ligantes , Redes e Vias Metabólicas , Modelos Moleculares , Ligação Proteica , Inibidores de Proteínas Quinases/uso terapêutico , Relação Estrutura-Atividade
5.
Molecules ; 26(21)2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34770990

RESUMO

In the current study, eight new hybrids of the NSAIDs, ibuprofen and ketoprofen with five pyrrolizine/indolizine derivatives were designed and synthesized. The chemical structures of these hybrids were confirmed by spectral and elemental analyses. The antiproliferative activities of these hybrids (5 µM) was investigated against MCF-7, A549, and HT-29 cancer cell lines using the cell viability assay, MTT assay. The results revealed 4-71% inhibition of the growth of the three cancer cell lines, where 8a,e,f were the most active. In addition, an investigation of the antiproliferative activity of 8a,e,f against MCF-7 cells revealed IC50 values of 7.61, 1.07, and 3.16 µM, respectively. Cell cycle analysis of MCF-7 cells treated with the three hybrids at 5 µM revealed a pro-apoptotic increase in cells at preG1 and cell cycle arrest at the G1 and S phases. In addition, the three hybrids induced early apoptotic events in MCF-7 cells. The results of the molecular docking of the three hybrids into COX-1/2 revealed higher binding free energies than their parent compounds 5a,c and the co-crystallized ligands, ibuprofen and SC-558. The results also indicated higher binding free energies toward COX-2 over COX-1. Moreover, analysis of the binding modes of 8a,e,f into COX-2 revealed partial superposition with the co-crystallized ligand, SC-558 with the formation of essential hydrogen bonds, electrostatic, or hydrophobic interactions with the key amino acid His90 and Arg513. The new hybrids also showed drug-likeness scores in the range of 1.06-2.03 compared to ibuprofen (0.65) and ketoprofen (0.57). These results above indicated that compounds 8a,e,f deserve additional investigation as potential anticancer candidates.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Antineoplásicos/farmacologia , Indolizinas/farmacologia , Simulação de Acoplamento Molecular , Pirróis/farmacologia , Anti-Inflamatórios não Esteroides/química , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Indolizinas/química , Pirróis/química , Células Tumorais Cultivadas
6.
PLoS One ; 19(6): e0304980, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38905247

RESUMO

BACKGROUND: Antibiotic resistance genes (ARGs) transfer rapidly among bacterial species all over the world contributing to the aggravation of antibiotic resistance crisis. Antibiotics at sub-inhibitory concentration induce horizontal gene transfer (HRT) between bacteria, especially through conjugation. The role of common non-antibiotic pharmaceuticals in the market in disseminating antibiotic resistance is not well studied. OBJECTIVES: In this work, we indicated the effect of some commonly used non-antibiotic pharmaceuticals including antiemetic (metoclopramide HCl) and antispasmodics (hyoscine butyl bromide and tiemonium methyl sulfate) on the plasmid-mediated conjugal transfer of antibiotic resistance genes between pathogenic E. coli in the gastric intestinal tract (GIT). METHODS: Broth microdilution assay was used to test the antibacterial activity of the tested non-antibiotic pharmaceuticals. A conjugation mating system was applied in presence of the studied non-antibiotic pharmaceuticals to test their effect on conjugal transfer frequency. Plasmid extraction and PCR were performed to confirm the conjugation process. Transmission electron microscopy (TEM) was used for imaging the effect of non-antibiotic pharmaceuticals on bacterial cells. RESULTS: No antibacterial activity was reported for the used non-antibiotic pharmaceuticals. Plasmid-mediated conjugal transfer between isolates was induced by metoclopramide HCl but suppressed by hyoscine butyl bromide. Tiemonium methylsulfate slightly promoted conjugal transfer. Aggregation between cells and periplasmic bridges was clear in the case of metoclopramide HCl while in presence of hyoscine butyl bromide little affinity was observed. CONCLUSION: This study indicates the contribution of non-antibiotic pharmaceuticals to the dissemination and evolution of antibiotic resistance at the community level. Metoclopramide HCl showed an important role in the spread of antibiotic resistance.


Assuntos
Escherichia coli , Transferência Genética Horizontal , Plasmídeos , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Plasmídeos/genética , Metoclopramida/farmacologia , Testes de Sensibilidade Microbiana , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Farmacorresistência Bacteriana/efeitos dos fármacos , Conjugação Genética , Resistência Microbiana a Medicamentos/genética , Resistência Microbiana a Medicamentos/efeitos dos fármacos
7.
Future Med Chem ; 16(11): 1053-1073, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38708686

RESUMO

Aim: This study focused on designing and synthesizing novel derivatives of 3,5,8-trisubstituted coumarin. Results: The synthesized compounds, particularly compound 5, exhibited significant cytotoxic effects on MCF-7 cells, surpassing staurosporine, and reduced toxicity toward MCF-10A cells, highlighting potential pharmacological advantages. Further, compound 5 altered the cell cycle and significantly increased apoptosis in MCF-7 cells, involving both early (41.7-fold) and late stages (33-fold), while moderately affecting necrotic signaling. The antitumor activity was linked to a notable reduction (4.78-fold) in topoisomerase IIß expression. Molecular modeling indicated compound 5's strong affinity for EGFR, human EGF2 and topoisomerase II proteins. Conclusion: These findings highlight compound 5 as a multifaceted antitumor agent for breast cancer.


[Box: see text].


Assuntos
Antineoplásicos , Apoptose , Neoplasias da Mama , Proliferação de Células , Cumarínicos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Cumarínicos/química , Cumarínicos/farmacologia , Cumarínicos/síntese química , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Neoplasias da Mama/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Feminino , Apoptose/efeitos dos fármacos , DNA Topoisomerases Tipo II/metabolismo , Relação Estrutura-Atividade , Células MCF-7 , Estrutura Molecular , Linhagem Celular Tumoral , Ciclo Celular/efeitos dos fármacos , Receptores ErbB/metabolismo , Receptores ErbB/antagonistas & inibidores
8.
Environ Sci Pollut Res Int ; 30(22): 62676-62688, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36947383

RESUMO

Simple and green strategy was described for the development of multifunctional polyester nanofibers (PNFs). Solution blow spinning (SBS) technology was applied to in situ immobilize nanocomposites of polyaniline (PANi) and silver nanoparticles (AgNPs) into plasma-treated polyester nanoscaled fibers prepared. The polyester nanofibers were prepared from recycled polyethylene terephthalate waste, which was exposed plasma-curing and a REDOX reaction in the presence of AgNO3, aniline, and CH3COONH4. Plasma-catalyzed oxidative polymerization of aniline to polyaniline together with a reductive process of Ag+ to silver nanoparticles led to their enduring insoluble dispersion into the surface of polyester nanofibers. By taking the advantage of the PANi oxidation, AgNPs were precipitated from an aqueous medium of AgNPs. The morphological properties were investigated by various analytical techniques. The polyester fiber diameter was determined in the range of 450-650 nm. In addition, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were utilized to examine AgNPs, demonstrating diameters of 4-20 nm. The plasma-uncured AgNPs/PANi immobilized nanofibrous film displayed weak absorption bands at 399 nm and 403 nm upon increasing the concentration of AgNPs. On the other hand, the plasma-cured AgNPs/PANi immobilized nanofibers displayed strong absorption bands at 526 nm and 568 nm upon increasing the concentration of AgNPs. The AgNP-induced antimicrobial performance and the PANi-induced electrically conductivity were explored. The prepared PNFs showed high UV protection.


Assuntos
Nanopartículas Metálicas , Nanofibras , Prata/farmacologia , Polietilenotereftalatos , Compostos de Anilina , Oxirredução
9.
Pharmaceuticals (Basel) ; 16(3)2023 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-36986525

RESUMO

1,3,4-Oxadiazole moiety is a crucial pharmacophore in many biologically active compounds. In a typical synthesis, probenecid was subjected to a sequence of reactions to obtain a 1,3,4-oxadiazole-phthalimide hybrid (PESMP) in high yields. The NMR (1H and 13C) spectroscopic analysis initially confirmed the structure of PESMP. Further spectral aspects were validated based on a single-crystal XRD analysis. Experimental findings were confirmed afterwards by executing a Hirshfeld surface (HS) analysis and quantum mechanical computations. The HS analysis showed the role of the π⋯π stacking interactions in PESMP. PESMP was found to have a high stability and lower reactivity in terms of global reactivity parameters. α-Amylase inhibition studies revealed that the PESMP was a good inhibitor of α-amylase with an s value of 10.60 ± 0.16 µg/mL compared with that of standard acarbose (IC50 = 8.80 ± 0.21 µg/mL). Molecular docking was also utilized to reveal the binding pose and features of PESMP against the α-amylase enzyme. Via docking computations, the high potency of PESMP and acarbose towards the α-amylase enzyme was unveiled and confirmed by docking scores of -7.4 and -9.4 kcal/mol, respectively. These findings shine a new light on the potential of PESMP compounds as α-amylase inhibitors.

10.
Pharmaceuticals (Basel) ; 16(1)2022 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-36678507

RESUMO

New S-alkyl phthalimide 5a-f and S-benzyl 6a-d analogs of 5-(2-phenylquinolin-4-yl)-1,3,4-oxadiazole-2-thiol (4) were prepared by reacting 4 with N-bromoalkylphthalimide and CF3-substituted benzyl bromides in excellent yields. Spectroscopic techniques were employed to elucidate the structures of the synthesized molecules. The inhibition activity of newly synthesized molecules toward MAO-A, MAO-B, and AChE enzymes, was also assessed. All these compounds showed activity in the submicromolar range against all enzymes. Compounds 5a and 5f were found to be the most potent compounds against MAO-A (IC50 = 0.91 ± 0.15 nM) and MAO-B (IC50 = 0.84 ± 0.06 nM), while compound 5c showed the most efficient acetylcholinesterase inhibition (IC50 = 1.02± 0.65 µM). Docking predictions disclosed the docking poses of the synthesized molecules with all enzymes and demonstrated the outstanding potency of compounds 5a, 5f, and 5c (docking scores = -11.6, -15.3, and -14.0 kcal/mol against MAO-A, MAO-B, and AChE, respectively). These newly synthesized analogs act as up-and-coming candidates for the creation of safer curative use against Alzheimer's illness.

11.
Sci Rep ; 11(1): 15750, 2021 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-34344971

RESUMO

Novel tri-and tetra-cyclic compounds based on the thiadiazolopyrimidine ring system were synthesized, and their antimicrobial activity was estimated. The obtained results evidenced the substantial efficiencies of pyrano-thiadiazolopyrimidine compounds 8a-b and 9a-b toward the two strains of gram-positive bacteria (S. aureus and B. cereus). Besides, tetracyclic pyrazolopyrimido-thiadiazolopyrimidine derivatives 16a-b and 17a-b displayed prominent efficiencies toward the two strains of gram-negative bacteria (E. coli and P. aeruginosa). In addition, compounds 8a-b and 9a-b displayed good efficacy toward C. albicans. The activity of antiquorum sensing (anti-QS) inhibition of the newly synthesized thiadiazolopyrimidine-based compounds toward C. violaceum was tested, suggesting satisfactory activity for derivatives 16a-b, 17a-b, 8b, and 9a. The cytotoxic activity of these derivatives was screened toward various cancer cell lines (MCF-7, PC3, Hep-2, and HepG2) and standard normal fibroblast cells (WI38) by utilizing the MTT assay. The pyrazolopyrimido-thiadiazolopyrimidine derivatives 16a, 16b17a, and 17b showed potent cytotoxic efficacy against the MCF-7 cells with the IC50 values ranging from 5.69 to 9.36 µM. Also, the endorsed structural activity relationship (SAR) of the inspected thiadiazolopyrimidine derivatives provided a correlation between the chemical structure and anticancer efficiency. The in silico docking studies were implemented for silencing the hormonal signaling in the breast (PDB Code-5NQR). The results were found to be consistent with the cytotoxic activity.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Antineoplásicos/farmacologia , Compostos Policíclicos/síntese química , Compostos Policíclicos/farmacologia , Pirimidinas/química , Tiadiazóis/química , Antibacterianos/química , Antifúngicos/química , Antineoplásicos/química , Bactérias/efeitos dos fármacos , Proliferação de Células , Fungos/efeitos dos fármacos , Ensaios de Triagem em Larga Escala , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Células Tumorais Cultivadas
12.
Pharmaceutics ; 13(8)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34452276

RESUMO

The main objective of this research work was the development and evaluation of transfersomes integrated oral films for the bioavailability enhancement of Ebastine (EBT) to treat allergic rhinitis. The flexible transfersomes, consisting of drug (EBT), lipid (Phosphatidylcholine) and edge activator (EA) Polyoxyethylene sorbitan monooleate or Sorbitan monolaurate, were prepared with the conventional thin film hydration method. The developed transfersomes were further integrated into oral films using the solvent casting method. Transfersomes were evaluated for their size distribution, surface charge, entrapment efficiency (EE%) and relative deformability, whereas the formulated oral films were characterized for weight, thickness, pH, folding endurance, tensile strength, % of elongation, degree of crystallinity, water content, content uniformity, in vitro drug release and ex vivo permeation, as well as in vivo pharmacokinetic and pharmacodynamics profile. The mean hydrodynamic diameter of transfersomes was detected to be 75.87 ± 0.55 nm with an average PDI and zeta potential of 0.089 ± 0.01 and 33.5 ± 0.39 mV, respectively. The highest deformability of transfersomes of 18.52 mg/s was observed in the VS-3 formulation. The average entrapment efficiency of the transfersomes was about 95.15 ± 1.4%. Transfersomal oral films were found smooth with an average weight, thickness and tensile strength of 174.72 ± 2.3 mg, 0.313 ± 0.03 mm and 36.4 ± 1.1 MPa, respectively. The folding endurance, pH and elongation were found 132 ± 1, 6.8 ± 0.2 and 10.03 ± 0.4%, respectively. The ex vivo permeability of EBT from formulation ETF-5 was found to be approximately 2.86 folds higher than the pure drug and 1.81 folds higher than plain film (i.e., without loaded transfersomes). The relative oral bioavailability of ETF-5 was 2.95- and 1.7-fold higher than that of EBT-suspension and plain film, respectively. In addition, ETF-5 suppressed the wheal and flare completely within 24 h. Based on the physicochemical considerations, as well as in vitro and in vivo characterizations, it is concluded that the highly flexible transfersomal oral films (TOFs) effectively improved the bioavailability and antihistamine activity of EBT.

13.
Int J Biol Macromol ; 163: 2236-2247, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32931835

RESUMO

Nanocomposite hydrogel film was prepared from Polyvinyl alcohol [PVA], Corn Starch [CS], Linseed oil polyol [LP], and silver nanoparticles [NP]. LP was prepared by epoxidation and hydration of Linseed oil [LO]. IR and NMR supported the insertion of hydroxyl groups in LP by epoxide ring opening reaction at epoxidized LO. Silver NP were biosynthesized using aqueous leaves' extract from locally grown Ocimum forsskaolii Benth [LEO] plant. FTIR, XRD, UV and TEM confirmed the synthesis of NP (size 30 to 39 nm). Transparent and foldable hydrogel film resulted by blending the constituents (PVA, CS, LP and NP), crosslinking by glutaraldehyde, at room temperature, and showed expansion in water, different pH solutions, biodegradation and good antibacterial and antifungal activity against tested microbes. Linseed polyol influenced the structure, morphology, hydrophilicity, improved swelling ability and thermal stability and accelerated biodegradation of hydrogel films. NP were well adhered to LP globules that were embedded in PVA/CS matrix as strung set of beads (LP globules) decorated with black pearls (spherical NP). Silver NP conferred antimicrobial behavior to hydrogel film as observed by antimicrobial screening on different microbes. The results were encouraging and showed that such hydrogel films may find prospective applications in antimicrobial packaging.


Assuntos
Antibacterianos/química , Nanopartículas Metálicas/química , Polímeros/química , Álcool de Polivinil/química , Antibacterianos/síntese química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Linho/química , Óleo de Semente do Linho , Nanocompostos/química , Polímeros/síntese química , Álcool de Polivinil/síntese química , Álcool de Polivinil/farmacologia , Prata/química , Amido/química , Zea mays/química
14.
RSC Adv ; 9(40): 23148-23155, 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-35514518

RESUMO

Interception of a dearomatized tertiary boronic ester, formed through a kinetically and thermodynamically favorable 1,2-metalate rearrangement/anti-SN2' elimination of an activated ortho-lithiated benzyl amine, in a [4+2] cycloaddition or 1,3-borotopic shift has been investigated by density functional theory (DFT). Although superacitvated "naked" Li+ was found to greatly promote 1,3-borotopic shift, the diastereoselective [4+2] cycloaddition was favored. It was revealed that the factor that controls the diastereoselectivity was the steric bulk provided by the diene, which is in agreement with experimental diastereoselectivity. A comparison of unreactive dienophiles such as maleic anhydride, diethyl maleate, and others with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (PTAD) was found to be in an excellent agreement with the experiments; where their lack of reactivity is attributed to the high deformation energies of the interacting components to achieve the transition state structure which was pronounced with the high energy of LUMO orbitals.

SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa