scholarly journals Palladium nanoparticle biosynthesis via Yerba Mate (Ilex paraguariensis) extract: an efficient eco-friendly catalyst for Suzuki–Miyaura reactions

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Cristiane R. Schmitt ◽  
Fábio A. Duarte ◽  
Marcelo Godoi ◽  
Carlos R. M. Peixoto ◽  
Fernanda Trombetta ◽  
...  
Keyword(s):  
Low Cost ◽  
Phenylboronic Acid ◽  
Cross Coupling ◽  
Ilex Paraguariensis ◽  
Yerba Mate ◽  
Palladium Nanoparticle ◽  
Ligand Free ◽  
Nanoparticle Biosynthesis ◽  
First Time ◽  
Catalyst Load

Abstract This manuscript relates, for the first time, palladium nanoparticle production by bio-reduction using an Ilex paraguariensis aqueous extract. The solid obtained, PdISM, was used as a catalyst in Suzuki–Miyaura cross-coupling, composing a new eco-friendly, ligand-free, and low cost catalytic system. Excellent yields were obtained in the coupling of aryl iodides and bromides with phenylboronic acid. The same catalyst load was able to be recycled 3x. Graphical Abstract

Microwave-assisted Cobalt-copper Dual Catalyzed Ligand Free C-Se Cross-coupling

2020 ◽  
Vol 7 (2) ◽  
pp. 157-163
Author(s):  
Debasish Kundu ◽  
Anup Roy ◽  
Subir Panja ◽  
Raj K. Singh
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Building Blocks ◽  
Transition Metal Catalysts ◽  
Metal Catalyst ◽  
Co Catalyst ◽  
Ligand Free ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
First Time

Background: Organoselenides are important building blocks of several biologically important molecules and natural products. Several protocols have been developed by chemists for their synthesis. Transition metal-catalyzed cross-coupling is a powerful tool for this purpose in the last two decades. Various transition metal catalysts e.g. Pd, Ni, Cu, In etc. have been used for performing C-Se cross-coupling in the presence or absence of ligands. Objective: Development of a sustainable protocol for transition metal-catalyzed C-Se cross-coupling is the main objective of this research. Recently, Cobalt has been applied as a cheap and sustainable transition metal catalyst in several organic reactions. This protocol is focused on applying cobalt salt as a catalyst for performing C-Se cross-coupling for the first time. Methods: Co(acac)2 has been successfully employed for performing Se-arylations in the presence of CuI, which acts as a co-catalyst under microwave irradiation. NMP was used as solvent and KOH as a reductant in this reaction. Results: Both iodo-and bromoarenes have been used to perform C-Se cross-coupling with diaryl diselenide under this Co/Cu dual catalytic system. The reaction was successful with both electrondonating and withdrawing groups in ortho-, meta-, and para-positions in the aromatic ring of Bromo and iodoarenes. Conclusion: This is an effective protocol for the preparation of organoselenides, catalyzed by cobalt in the presence of copper. The mechanism has been established by several experimental techniques.

scholarly journals Antibacterial activity of Ilex paraguariensis (Yerba Mate) against Gram-positive and Gram-negative bacteria

2018 ◽  
Vol 12 (02.1) ◽  
pp. 13S
Author(s):  
Tania Noureddine ◽  
Ziad Al Husseini ◽  
Ali Nehme ◽  
Roula Abdel Massih
Keyword(s):  
Antibacterial Activity ◽  
Aqueous Extract ◽  
Phenylboronic Acid ◽  
Ilex Paraguariensis ◽  
Resistant Bacteria ◽  
Molecular Testing ◽  
Yerba Mate ◽  
Bacterial Strains ◽  
Gram Positive ◽  
Gram Negative

Introduction: Limited research was performed on the antibacterial activity of the aqueous extract of Yerba Mate. The purpose of this study is to evaluate the anti-bacterial activity of Yerba Mate against Gram-positive and Gram-negative bacterial strains and its action against some resistant bacteria with genotypic molecular testing of resistance profiles. Methodology: Commercial Ilex paraguariensis stems and leaves were purchased and extracts were prepared by adding water at 70oC for 2 hrs. ATCC bacterial strains and clinical strains from Centre Hospitalier Du Nord (CHN) were used for testing. Macro dilution method was used to determine the minimal inhibitory. Minimal bactericidal concentration (MBC) was determined by sub-culturing the tubes with clear broth. For phenotypic and genotypic detection of β-lactamases, Double Disk Synergy method, E-test, phenylboronic acid disc method and multiplex PCR were performed for the identification of the mechanisms of resistance. Results: Antibacterial activity was observed against all tested strains, with a greater activity against Gram-positive bacteria. This study showed mostly a greater antibacterial activity of aqueous extract of Yerba Mate in comparison to different extraction methods published. In general, the MIC and MBC values ranged between 0.468 mg/mL and 15 mg/mL. No correlation was found between the different molecular resistance profiles and the antibacterial activity. Conclusion: More studies are needed to determine the molecule or molecules responsible for this activity. Moreover, testing a wider range of bacterial isolates is important for a better understanding of the potential role of Yerba Mate.

Alkaline pretreatment of yerba mate (Ilex paraguariensis) waste for unlocking low-cost cellulosic biofuel

Fuel ◽  
2020 ◽  
Vol 266 ◽  
pp. 117068 ◽  
Author(s):  
Antônio Djalma Nunes Ferraz Júnior ◽  
Maria Ines Etchelet ◽  
Adriana Ferreira Maluf Braga ◽  
Leonardo Clavijo ◽  
Inés Loaces ◽  
...  
Keyword(s):  
Low Cost ◽  
Alkaline Pretreatment ◽  
Ilex Paraguariensis ◽  
Yerba Mate ◽  
Cellulosic Biofuel

First ligand-free, microwave-assisted, Heck cross-coupling reaction in pure water on a nucleoside – application to the synthesis of antiviral BVDU

RSC Advances ◽  
2014 ◽  
Vol 4 (87) ◽  
pp. 46926-46929 ◽  
Author(s):  
Gwénaëlle Hervé ◽  
Christophe Len
Keyword(s):  
Pure Water ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Microwave Assisted ◽  
Cross Coupling Reaction ◽  
Ligand Free ◽  
Palladium Catalyzed ◽  
Microwave Assistance ◽  
First Time

For the first time, a palladium catalyzed Heck cross-coupling reaction between 5-iodo-2′-deoxyuridine and various acrylate derivatives was performed using ligand-free conditions and microwave assistance in pure water.

Dual Nickel/Palladium-Catalyzed Reductive Cross-Coupling Reactions Between Two Phenol Derivatives

2020 ◽  
Author(s):  
Baojian Xiong ◽  
Yue Li ◽  
Yin Wei ◽  
Søren Kramer ◽  
Zhong Lian
Keyword(s):  
Functional Group ◽  
Low Cost ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Phenol Derivatives ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
One Step ◽  
Aryl Tosylates ◽  
Low Sensitivity

Cross-coupling between substrates that can be easily derived from phenols is highly attractive due to the abundance and low cost of phenols. Here, we report a dual nickel/palladium-catalyzed reductive cross-coupling between aryl tosylates and aryl triflates; both substrates can be accessed in just one step from readily available phenols. The reaction has a broad functional group tolerance and substrate scope (>60 examples). Furthermore, it displays low sensitivity to steric effects demonstrated by the synthesis of a 2,2’disubstituted biaryl and a fully substituted aryl product. The widespread presence of phenols in natural products and pharmaceuticals allow for straightforward late-stage functionalization, illustrated with examples such as Ezetimibe and tyrosine. NMR spectroscopy and DFT calculations indicate that the nickel catalyst is responsible for activating the aryl triflate, while the palladium catalyst preferentially reacts with the aryl tosylate.

Copper-Catalyzed Hydrocarboxylation of Allenes

2019 ◽  
Author(s):  
Rémi blieck ◽  
Marc Taillefer ◽  
Florian Monnier
Keyword(s):  
Carboxylic Acids ◽  
Copper Catalysis ◽  
Ligand Free ◽  
First Time

The addition of carboxylic acids to allenes was performed for the first time with copper catalysis. The hydrocarboxylation reaction is totally regio- and stereoselective, ligand-free and used catalytic amounts of copper and base.

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

scholarly journals UV Inscription and Pressure Induced Long-Period Gratings through 3D Printed Amplitude Masks

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1977
Author(s):  
Ricardo Oliveira ◽  
Liliana M. Sousa ◽  
Ana M. Rocha ◽  
Rogério Nogueira ◽  
Lúcia Bilro
Keyword(s):  
State Of The Art ◽  
Low Cost ◽  
Resonance Wavelength ◽  
Complex Structures ◽  
Pressing Method ◽  
Long Period ◽  
Long Period Gratings ◽  
3D Printed ◽  
Mechanical Pressing ◽  
First Time

In this work, we demonstrate for the first time the capability to inscribe long-period gratings (LPGs) with UV radiation using simple and low cost amplitude masks fabricated with a consumer grade 3D printer. The spectrum obtained for a grating with 690 µm period and 38 mm length presented good quality, showing sharp resonances (i.e., 3 dB bandwidth < 3 nm), low out-of-band loss (~0.2 dB), and dip losses up to 18 dB. Furthermore, the capability to select the resonance wavelength has been demonstrated using different amplitude mask periods. The customization of the masks makes it possible to fabricate gratings with complex structures. Additionally, the simplicity in 3D printing an amplitude mask solves the problem of the lack of amplitude masks on the market and avoids the use of high resolution motorized stages, as is the case of the point-by-point technique. Finally, the 3D printed masks were also used to induce LPGs using the mechanical pressing method. Due to the better resolution of these masks compared to ones described on the state of the art, we were able to induce gratings with higher quality, such as low out-of-band loss (0.6 dB), reduced spectral ripples, and narrow bandwidths (~3 nm).

Vegetative propagation, chemical composition and antioxidant activity of yerba mate genotypes

2021 ◽  
pp. 1-10
Author(s):  
Leandro Marcolino Vieira ◽  
Renata de Almeida Maggioni ◽  
Jéssica de Cássia Tomasi ◽  
Erik Nunes Gomes ◽  
Ivar Wendling ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Phenolic Compounds ◽  
Vegetative Propagation ◽  
Adventitious Rooting ◽  
Ilex Paraguariensis ◽  
Total Phenolic ◽  
Yerba Mate ◽  
Total Phenolic Compounds ◽  
Leaf Retention ◽  
Correlated Components

Abstract Ilex paraguariensis, commonly known as yerba mate, is a tree species native to South America. Its commercial value is due to the manufacturing of teas, with potential also in the pharmacological and cosmetic industries. Vegetative propagation of yerba mate is considered an innovation to the traditional production systems based on sexual propagation. The present study aimed to evaluate the rhizogenic potential and chemical attributes of mini-cuttings from 15 yerba mate genotypes, as well as to verify the correlation between phytochemical and rooting-related variables. Mini-cuttings were collected from a pre-existing mini-clonal hedge and the experimental design was completely randomized, with 15 treatments (genotypes), four replications and 10 mini-cuttings per plot. After 120 days, mini-cuttings were assessed regarding rooting, mortality, callogenesis and leaf retention percentages, percentage of mini-cuttings with both calluses and roots, number of roots and average root length. At the time of collection, subsamples from each plot were used for phytochemical analyses including total phenolic compounds, protein, caffeine and theobromine contents and antioxidant activity. Rooting percentages ranged from 5 to 72.5%, with significant variation among genotypes. Adventitious rooting and phytochemical profile of yerba mate mini-cuttings are genotype-dependent. Leaf retention is a relevant factor in the rooting of yerba mate mini-cuttings and the levels of total phenolic compounds, antioxidants and theobromine present in mini-cuttings are negatively correlated components to Ilex paraguariensis adventitious rooting.

Umpolung Coupling of Pyridine-2-carboxaldehydes and Propargylic Carbonates via N-Heterocyclic Carbene/Palladium Synergetic Catalysis

2021 ◽  
Author(s):  
Weiyang Bi ◽  
Yunhui Yang ◽  
Song Ye ◽  
Congyang Wang
Keyword(s):  
Palladium Catalyst ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Cooperative Catalysis ◽  
Cross Coupling Reaction ◽  
First Time

The umpolung cross-coupling reaction of pyridine-2-carboxaldehydes and propargylic carbonates has been developed for the first time through N-heterocyclic carbene/palladium cooperative catalysis with the judicious selections of the palladium catalyst, ligand...

Sign in / Sign up

Export Citation Format

Share Document