Surface Charges of Porous Coordination Cage Tune the Catalytic Reactivity of Knoevenagel Condensation

We report the first total synthesis of (+)-granatumine A, a limonoid alkaloid with PTP-1B inhibitory activity, in 10 steps. Over the course of this study, two key methodological advances were made: a cost effective procedure for ketone alpha,beta-dehydrogenation using allyl-Pd catalysis, and a Pd-catalyzed protocol to convert epoxyketones to 1,3-diketones. The central tetrasubstituted pyridine is formed by a convergent Knoevenagel condensation and carbonyl-selective electrocyclization cascade, which was followed by a direct transformation of a 2<i>H</i>-pyran to a pyridine. These studies have led to the structural revision of two members of this family.

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Preparation of TiO2 Nano-particles with Controllable Surface Charges for Electrophoretic Display

Journal of Inorganic Materials ◽

10.3724/sp.j.1077.2012.00649 ◽

2012 ◽

Vol 27 (6) ◽

pp. 649-654 ◽

Cited By ~ 3

Author(s):

Zhi-Jie LIU ◽

Xiang-Gao LI ◽

Shi-Rong WANG

Keyword(s):

Nano Particles ◽

Surface Charges ◽

Electrophoretic Display

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Carboxymethyl-hexanoyl Chitosan Nanodroplets for Ultrasonic Imaging and Drug Delivery to Tumor

Current Pharmaceutical Design ◽

10.2174/1381612824666180515122836 ◽

2018 ◽

Vol 24 (15) ◽

pp. 1682-1688 ◽

Cited By ~ 3

Author(s):

Yu Jinsui ◽

Situ Bing ◽

Luo Muhua ◽

Li Yue ◽

Liao Jianyi ◽

...

Keyword(s):

Ultrasound Imaging ◽

Tumor Therapy ◽

Carboxymethyl Chitosan ◽

Great Promise ◽

Ovarian Cancer Cells ◽

Mechanical Index ◽

Surface Charges ◽

Particle Structure ◽

Drug Release Profile ◽

Hexanoyl Chitosan

Introduction: Although a great many strategies have been proposed for tumor-targeted chemotherapy, current delivery methods of anticancer drugs present limited success with inevitable systemic toxicity. The aim of this study was to develop a new kind of theranostic carrier for targeted tumor therapy. Methods: Prior to prepare CHC-PFP-DOX, carboxymethyl-hexanoyl chitosan (CHC) was synthesized by acylation of carboxymethyl chitosan. To develop CHC-PFP, perfluoropentane (PFP), an ultrasound gas precursor, was simultaneously encapsulated into the hydrophobic inner cores of pre-formulated CHC micelle in aqueous phase via using the oil in water (O/W) emulsion method. The size distribution and surface charges of these nanodroplets were measured and the morphology was observed by transmission electron microscopy (TEM). For ultrasound imaging application, in vitro model was established to evaluate the imaging of CHC-PFP-DOX under different concentration and mechanical index. After that, the anti-tumor effect of ultrasound combined with CHC-PFPDOX on ovarian cancer cells was investigated. Results: The resulting CHC-PFP-DOX had a nano-sized particle structure, with hydrophobic anticancer DOX/PFP inner cores and a hydrophilic carboxymethyl chitosan polymer outer shell. The favorable nano-scaled size offers the potential to extravagate from veins and accumulate in tumor tissues via enhanced permeation and retention (EPR) effect. Additionally, CHC-PFP-DOX showed the ability to serve as ultrasound imaging agent at body temperature. Notably, it exhibited an ultrasound-triggered drug release profile through the external ultrasound irradiation. Further study demonstrated that ultrasound combined with CHC-PFP-DOX can improve the killing effect of chemotherapy for tumor. Conclusion: CHC-PFP-DOX holds great promise in simultaneous cancer-targeting ultrasound imaging and ultrasound- mediated delivery for cancer chemotherapy.

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Knoevenagel Condensation Reactions of Cyano Malononitrile-Derivatives Under Microwave Radiation

Current Organic Chemistry ◽

10.2174/1385272822666180123145819 ◽

2018 ◽

Vol 22 (6) ◽

pp. 519-532 ◽

Cited By ~ 6

Author(s):

Lucas Lima Zanin ◽

David Esteban Quintero Jimenez ◽

Luis Pina Fonseca ◽

Andre Luiz Meleiro Porto

Keyword(s):

Microwave Radiation ◽

Knoevenagel Condensation ◽

Condensation Reactions

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O-AcylTEMPOs, a Modified and Fundamental, but Unexplored Carboxylic Derivative: Recent Progress in Synthetic Applications

Current Organic Chemistry ◽

10.2174/1385272823666191019102511 ◽

2019 ◽

Vol 23 (19) ◽

pp. 2102-2121

Author(s):

Hiroyuki Kawafuchi ◽

Lijian Ma ◽

Md Imran Hossain ◽

Tsutomu Inokuchi

Keyword(s):

Organic Synthesis ◽

Recent Progress ◽

Knoevenagel Condensation ◽

Acid Synthesis ◽

Amino Acid Synthesis ◽

Electrophilic Amination ◽

Weinreb Amides ◽

Anionic Species ◽

Diastereoselective Addition ◽

Carbonyl Function

O-Acylated 2,2,6,6-tetramethylpiperidine-N-oxyls (abbr. O-AcylTEMPOs) are easily available and stable carboxylic derivatives, but their utility in organic synthesis is unexplored in contrast to analogues, such as the N-methoxy-N-methylamides, known as Weinreb amides. Especially, the O–N unit of the O-acylTEMPOs dictates a fairly electronwithdrawing character for the carbonyl function. This enhances the reactivity and stability of the resulting enolate ions. Accordingly, O-acylTEMPOs allow various transformations and this review encompasses seven topics: (1) Reactivity of O-acylTEMPOs towards nucleophiles and chemoselective transformations, (2) Reactivity of anionic species derived from O-acylTEMPOs, (3) E-Selective Knoevenagel condensation of acetoacetylTEMPOs and synthesis of furans, (4) Electrocyclization of 2,4-dienones derived from acetoacetic derivatives and 2-substituted enals, (5) Diastereoselective addition of amide anion to O-(2-alkenoyl)TEMPOs and β-amino acid synthesis, (6) Thermolysis of O-acylTEMPOs, and (7) Applications for Umpolung reactions using O-benzoylTEMPOs, useful for the electrophilic amination of alkenes and alkynes.

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Temperature Dependent Green Synthesis of 3-Carboxycoumarins and 3,4-unsubstituted Coumarins

Current Organic Synthesis ◽

10.2174/1570179415666180924124134 ◽

2019 ◽

Vol 16 (1) ◽

pp. 130-135 ◽

Cited By ~ 3

Author(s):

Jack van Schijndel ◽

Dennis Molendijk ◽

Luiz Alberto Canalle ◽

Erik Theodorus Rump ◽

Jan Meuldijk

Keyword(s):

Knoevenagel Condensation ◽

Ammonium Bicarbonate ◽

Solvent Free ◽

Temperature Dependent ◽

Step Procedure ◽

Synthetic Routes ◽

High Yields ◽

Temperature Optima ◽

Solvent Free Synthesis ◽

Full Conversion

Aim and Objective: Because of the low abundance of 3,4-unsubstituted coumarins in plants combined with the complex purification process required, synthetic routes towards 3,4-unsubstituted coumarins are especially valuable. In the present work, we explore the possibilities of a solvent-free Green Knoevenagel condensation on various 2-hydroxybenzaldehyde derivatives and malonic acid without the use of toxic organocatalysts like pyridine and piperidine but only use ammonium bicarbonate as the catalyst. Materials and Methods: To investigate the scope of the Green Knoevenagel condensation for the synthesis of 3,4-unsubstituted coumarins, various 2-hydroxybenzaldehyde derivatives were screened as starting material in the optimized two-step procedure developed for 2-hydroxybenzaldehyde. </P><P> Results: This study shows that the intramolecular esterification and the decarboxylation are in competition, but show different temperature optima. In order to suppress premature decarboxylation and maximize the yield of coumarin, a two-step procedure was adopted. The reaction mixture containing ammonium bicarbonate is initially kept at 90ºC for 1 hour. After completion of the cyclization, the temperature of the reaction mixture is increased to 140ºC for 2 hours. Following this protocol, coumarin could be isolated with a yield of 95%. Conclusion: A two-step procedure for the solvent-free synthesis of several 3,4-unsubstituted coumarins was developed using ammonium bicarbonate, resulting in high yields of the desired products. Moreover, this procedure has a low E-factor and is, therefore an environmental friendly reaction in line with the principles of Green Chemistry. It was shown that by initially capping the temperature at 90ºC, premature decarboxylation can be suppressed. After full conversion to the intermediate 3-carboxycoumarin, the temperature can be increased to 140ºC finalizing the reaction. Ammonium bicarbonate was shown to catalyze both the Green Knoevenagel condensation and the decarboxylation step.

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Evaluation of Surface-modified Superparamagnetic Iron Oxide Nanoparticles to Optimize Bacterial Immobilization for Bio-separation with the Least Inhibitory Effect on Microorganism Activity

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681208666181015120346 ◽

2020 ◽

Vol 10 (2) ◽

pp. 166-174

Author(s):

Mehdi Khoshneviszadeh ◽

Sarah Zargarnezhad ◽

Younes Ghasemi ◽

Ahmad Gholami

Keyword(s):

Iron Oxide ◽

Amino Acid ◽

Magnetic Nanoparticles ◽

Iron Oxide Nanoparticles ◽

Surface Coating ◽

Superparamagnetic Iron Oxide ◽

Superparamagnetic Iron Oxide Nanoparticles ◽

Oxide Nanoparticles ◽

Surface Charges ◽

Surface Modified

Background: Magnetic cell immobilization has been introduced as a novel, facile and highly efficient approach for cell separation. A stable attachment between bacterial cell wall with superparamagnetic iron oxide nanoparticles (SPIONs) would enable the microorganisms to be affected by an outer magnetic field. At high concentrations, SPIONs produce reactive oxygen species in cytoplasm, which induce apoptosis or necrosis in microorganisms. Choosing a proper surface coating could cover the defects and increase the efficiency. Methods: In this study, asparagine, APTES, lipo-amino acid and PEG surface modified SPIONs was synthesized by co-precipitation method and characterized by FTIR, TEM, VSM, XRD, DLS techniques. Then, their protective effects against four Gram-positive and Gram-negative bacterial strains including Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were examined through microdilution broth and compared to naked SPION. Results: The evaluation of characterization results showed that functionalization of magnetic nanoparticles could change their MS value, size and surface charges. Also, the microbial analysis revealed that lipo-amino acid coated magnetic nanoparticles has the least adverse effect on microbial strain among tested SPIONs. Conclusion: This study showed lipo-amino acid could be considered as the most protective and even promotive surface coating, which is explained by its optimizing effect on cell penetration and negligible reductive effects on magnetic properties of SPIONs. lipo-amino acid coated magnetic nanoparticles could be used in microbial biotechnology and industrial microbiology.

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