scholarly journals Evidence for a Radical Mechanism in Cu(II)-Promoted SnAP Reactions

Synlett ◽  
2019 ◽  
Vol 30 (04) ◽  
pp. 464-470 ◽  
Author(s):  
Michael Luescher ◽  
Jeffrey Bode
Keyword(s):  
Nitrogen Heterocycles ◽  
Radical Cyclization ◽  
Bioactive Molecules ◽  
Current Understanding ◽  
Radical Mechanism ◽  
Radical Trapping ◽  
Wide Range ◽  
Aldehydes And Ketones ◽  
One Step ◽  
Radical Clock

Saturated nitrogen heterocycles can be found with increasing abundance in bioactive molecules despite a limited number of methods to access these scaffolds. However, the coupling of recently introduced SnAP [tin (Sn) amine protocol] reagents with a wide range of aldehydes and ketones has proven to be a reliable, practical, and versatile one-step approach to saturated N-heterocycles. While effective, the lack of mechanistic understanding limits efforts to develop new catalytic and enantioselective variants. To distinguish between a polar or radical mechanism, we assessed Lewis and Brønsted acids, radical trapping experiments, and radical clock SnAP reagents reinforcing the current understanding of the SnAP protocol as a radical cyclization.

scholarly journals A Photo-Enzymatic Cascade to Transform Racemic Alcohols into Enantiomerically Pure Amines

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 305 ◽  
Author(s):  
Jenő Gacs ◽  
Wuyuan Zhang ◽  
Tanja Knaus ◽  
Francesco G. Mutti ◽  
Isabel W.C.E. Arends ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Reductive Amination ◽  
Aerobic Oxidation ◽  
Secondary Alcohols ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Step Procedure ◽  
Wide Range ◽  
Aldehydes And Ketones ◽  
One Step

The consecutive photooxidation and reductive amination of various alcohols in a cascade reaction were realized by the combination of a photocatalyst and several enzymes. Whereas the photocatalyst (sodium anthraquinone-2-sulfonate) mediated the light-driven, aerobic oxidation of primary and secondary alcohols, the enzymes (various ω-transaminases) catalyzed the enantio-specific reductive amination of the intermediate aldehydes and ketones. The system worked in a one-pot one-step fashion, whereas the productivity was significantly improved by switching to a one-pot two-step procedure. A wide range of aliphatic and aromatic compounds was transformed into the enantiomerically pure corresponding amines via the photo-enzymatic cascade.

Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

2020 ◽  
Vol 24 (8) ◽  
pp. 900-908
Author(s):  
Ram Naresh Yadav ◽  
Amrendra K Singh ◽  
Bimal Banik
Keyword(s):  
Asymmetric Synthesis ◽  
Chiral Auxiliary ◽  
Bioactive Molecules ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Stereoselective Glycosylation ◽  
One Pot Synthesis ◽  
Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

scholarly journals One-step preparation of antimicrobial silicone materials based on PDMS and salicylic acid: insights from spatially and temporally resolved techniques

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Luca Barbieri ◽  
Ioritz Sorzabal Bellido ◽  
Alison J. Beckett ◽  
Ian A. Prior ◽  
Jo Fothergill ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Laser Scanning ◽  
Pathogenic Bacteria ◽  
Pharmaceutical Products ◽  
Laser Scanning Microscopy ◽  
Wound Dressings ◽  
Confocal Laser ◽  
Vis Spectroscopy ◽  
Wide Range ◽  
One Step

AbstractIn this work, we introduce a one-step strategy that is suitable for continuous flow manufacturing of antimicrobial PDMS materials. The process is based on the intrinsic capacity of PDMS to react to certain organic solvents, which enables the incorporation of antimicrobial actives such as salicylic acid (SA), which has been approved for use in humans within pharmaceutical products. By combining different spectroscopic and imaging techniques, we show that the surface properties of PDMS remain unaffected while high doses of the SA are loaded inside the PDMS matrix. The SA can be subsequently released under physiological conditions, delivering a strong antibacterial activity. Furthermore, encapsulation of SA inside the PDMS matrix ensured a diffusion-controlled release that was tracked by spatially resolved Raman spectroscopy, Attenuated Total Reflectance IR (ATR-IR), and UV-Vis spectroscopy. The biological activity of the new material was evaluated directly at the surface and in the planktonic state against model pathogenic bacteria, combining confocal laser scanning microscopy, electron microscopy, and cell viability assays. The results showed complete planktonic inhibition for clinically relevant strains of Staphylococcus aureus and Escherichia coli, and a reduction of up to 4 orders of magnitude for viable sessile cells, demonstrating the efficacy of these surfaces in preventing the initial stages of biofilm formation. Our approach adds a new option to existing strategies for the antimicrobial functionalisation of a wide range of products such as catheters, wound dressings and in-dwelling medical devices based on PDMS.

scholarly journals Photocatalytic three-component asymmetric sulfonylation via direct C(sp3)-H functionalization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shi Cao ◽  
Wei Hong ◽  
Ziqi Ye ◽  
Lei Gong
Keyword(s):  
Asymmetric Catalysis ◽  
Organic Synthesis ◽  
Photochemical Reaction ◽  
Low Cost ◽  
Bioactive Molecules ◽  
Atom Economy ◽  
Mild Conditions ◽  
Wide Range ◽  
Unsaturated Carbonyl Compound ◽  
Direct Functionalization

AbstractThe direct and selective C(sp3)-H functionalization of cycloalkanes and alkanes is a highly useful process in organic synthesis owing to the low-cost starting materials, the high step and atom economy. Its application to asymmetric catalysis, however, has been scarcely explored. Herein, we disclose our effort toward this goal by incorporation of dual asymmetric photocatalysis by a chiral nickel catalyst and a commercially available organophotocatalyst with a radical relay strategy through sulfur dioxide insertion. Such design leads to the development of three-component asymmetric sulfonylation involving direct functionalization of cycloalkanes, alkanes, toluene derivatives or ethers. The photochemical reaction of a C(sp3)-H precursor, a SO2 surrogate and a common α,β-unsaturated carbonyl compound proceeds smoothly under mild conditions, delivering a wide range of biologically interesting α-C chiral sulfones with high regio- and enantioselectivity (>50 examples, up to >50:1 rr and 95% ee). This method is applicable to late-stage functionalization of bioactive molecules, and provides an appealing access to enantioenriched compounds starting from the abundant hydrocarbon compounds.

scholarly journals Recent Advancements in Polymer/Liposome Assembly for Drug Delivery: From Surface Modifications to Hybrid Vesicles

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1027
Author(s):  
Vincenzo De Leo ◽  
Francesco Milano ◽  
Angela Agostiano ◽  
Lucia Catucci
Keyword(s):  
Drug Delivery ◽  
First Generation ◽  
Phospholipid Bilayer ◽  
Bioactive Molecules ◽  
Systemic Delivery ◽  
Molecular Weights ◽  
Liposome Preparation ◽  
Wide Range ◽  
Liposome Surface

Liposomes are consolidated and attractive biomimetic nanocarriers widely used in the field of drug delivery. The structural versatility of liposomes has been exploited for the development of various carriers for the topical or systemic delivery of drugs and bioactive molecules, with the possibility of increasing their bioavailability and stability, and modulating and directing their release, while limiting the side effects at the same time. Nevertheless, first-generation vesicles suffer from some limitations including physical instability, short in vivo circulation lifetime, reduced payload, uncontrolled release properties, and low targeting abilities. Therefore, liposome preparation technology soon took advantage of the possibility of improving vesicle performance using both natural and synthetic polymers. Polymers can easily be synthesized in a controlled manner over a wide range of molecular weights and in a low dispersity range. Their properties are widely tunable and therefore allow the low chemical versatility typical of lipids to be overcome. Moreover, depending on their structure, polymers can be used to create a simple covering on the liposome surface or to intercalate in the phospholipid bilayer to give rise to real hybrid structures. This review illustrates the main strategies implemented in the field of polymer/liposome assembly for drug delivery, with a look at the most recent publications without neglecting basic concepts for a simple and complete understanding by the reader.

scholarly journals Mesoporous Silica Nanoparticles and Mesoporous Bioactive Glasses for Wound Management: From Skin Regeneration to Cancer Therapy

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3337
Author(s):  
Sara Hooshmand ◽  
Sahar Mollazadeh ◽  
Negar Akrami ◽  
Mehrnoosh Ghanad ◽  
Ahmed El-Fiqi ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Mesoporous Silica Nanoparticles ◽  
Skin Regeneration ◽  
Bioactive Molecules ◽  
Wound Management ◽  
Bioactive Glasses ◽  
Wide Range

Exploring new therapies for managing skin wounds is under progress and, in this regard, mesoporous silica nanoparticles (MSNs) and mesoporous bioactive glasses (MBGs) offer great opportunities in treating acute, chronic, and malignant wounds. In general, therapeutic effectiveness of both MSNs and MBGs in different formulations (fine powder, fibers, composites etc.) has been proved over all the four stages of normal wound healing including hemostasis, inflammation, proliferation, and remodeling. The main merits of these porous substances can be summarized as their excellent biocompatibility and the ability of loading and delivering a wide range of both hydrophobic and hydrophilic bioactive molecules and chemicals. In addition, doping with inorganic elements (e.g., Cu, Ga, and Ta) into MSNs and MBGs structure is a feasible and practical approach to prepare customized materials for improved skin regeneration. Nowadays, MSNs and MBGs could be utilized in the concept of targeted therapy of skin malignancies (e.g., melanoma) by grafting of specific ligands. Since potential effects of various parameters including the chemical composition, particle size/morphology, textural properties, and surface chemistry should be comprehensively determined via cellular in vitro and in vivo assays, it seems still too early to draw a conclusion on ultimate efficacy of MSNs and MBGs in skin regeneration. In this regard, there are some concerns over the final fate of MSNs and MBGs in the wound site plus optimal dosages for achieving the best outcomes that deserve careful investigation in the future.

scholarly journals Phytochemicals and Antioxidant Activity in Oat-Buckwheat Dough and Cookies with Added Spices or Herbs

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2267
Author(s):  
Małgorzata Starowicz ◽  
Saruhan Arpaci ◽  
Joanna Topolska ◽  
Małgorzata Wronkowska
Keyword(s):  
Antioxidant Activity ◽  
Phenolic Content ◽  
Weight Basis ◽  
Bioactive Molecules ◽  
Total Phenolic ◽  
Antioxidant Power ◽  
Wide Range ◽  
Confectionery Products ◽  
Ferric Reducing Antioxidant Power ◽  
Phytochemical Contents

The aim of this study was to determine the phytochemicals and antioxidant activity in oat-buckwheat doughs and cookies with the addition of ten selected spices or herbs (2 g/100 g flours weight basis). The used spices and herbs, as was expected, showed a wide range of bioactive molecules, namely phenolic acids and flavonoids, and they are a rich source of components with antioxidant potential. All analysed oat-buckwheat dough showed higher antioxidant activity potential and higher total phenolic content (TPC) compared to cookies. The highest TPC was found in clove, both dough and cookies, with its addition showing the highest ferric reducing antioxidant power. Generally, cookies with the addition of spice/herbs showed higher phytochemical contents and antioxidant activity compared to oat-buckwheat cookies without the condiment. The technology of obtaining confectionery products, like oat-buckwheat cookies, that will favor the protection of bioactive compounds should still be improved.

scholarly journals One-step preparation of Cr2O3-based ink with long-term dispersion stability for inkjet applications

2021 ◽  
Author(s):  
Dongjin Xie ◽  
Qiuyi Luo ◽  
Shen Zhou ◽  
Mei Zu ◽  
Haifeng Cheng
Keyword(s):  
High Precision ◽  
Inkjet Printing ◽  
Printed Electronics ◽  
Direct Writing ◽  
Deposition Technique ◽  
Functional Material ◽  
Wide Range ◽  
One Step ◽  
Oled Display

Inkjet printing of functional material has shown a wide range of application in advertzing, OLED display, printed electronics and other specialized utilities that require high-precision, mask-free, direct-writing deposition technique. Nevertheless,...

scholarly journals Recurrent Novae — A Review

2015 ◽  
Vol 2 (1) ◽  
pp. 246-251 ◽  
Author(s):  
K. Mukai
Keyword(s):  
Accretion Rate ◽  
Current Understanding ◽  
X Rays ◽  
Symbiotic Star ◽  
Classical Novae ◽  
Extensive Data ◽  
Star Evolution ◽  
Wide Range ◽  
Multi Wavelength ◽  
Recurrent Nova

In recent years, recurrent nova eruptions are often observed very intensely in wide range of wavelengths from radio to optical to X-rays. Here I present selected highlights from recent multi-wavelength observations. The enigma of T Pyx is at the heart of this paper. While our current understanding of CV and symbiotic star evolution can explain why certain subset of recurrent novae have high accretion rate, that of T Pyx must be greatly elevated compared to the evolutionary mean. At the same time, we have extensive data to be able to estimate how the nova envelope was ejected in T Pyx, and it turns to be a rather complex tale. One suspects that envelope ejection in recurrent and classical novae in general is more complicated than the textbook descriptions. At the end of the review, I will speculate that these two may be connected.

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