Financial support from the DFG (Heisenberg scholarship to M.K., KL 2221/4-1; KL 2221/3-1) and the Max-Planck-Institut fuer Kohlenforschung is gratefully acknowledged.

1. Sintesi di Tetrahydrocarbazole idroperossidi <ol><li> La formazione del idroperossido viene rallentato se il tetrahydrocarbazole è molto colorato. In questo caso, purificarlo per ricristallizzazione usando toluene / pentano o mediante cromatografia su colonna per ottenere un materiale di partenza incolore. Per purificazione mediante cromatografia su colonna, imballare una colonna con uno strato inferiore di gel di silice e uno strato superiore di allumina. Mettere il tetrahydrocarbazole sulla sommità della colonna ed eluire con toluene. Tutti i sottoprodotti di colore giallo e nero indesiderati sono adsorbiti sulla colonna e tetrahydrocarbazole incolore di eluizione. Subito evaporare il solvente e conservare il prodotto bianco purificato sotto un&#39;atmosfera di argon al buio. </li><li> Pesare 1 g di tetrahydrocarbazole o di un tetrahydrocarbazole sostituito (1, sintetizzato secondo metodi riportati 16) in un pallone da 250 ml. Aggiungere 100 ml di toluene a questo pallone. </li><li> Pesare Rosa Bengala (2mg) e inserirlo nella miscela di reazione di cui sopra. </li><li> Aggiungere un ancoretta e coprire il pallone con setti. </li><li> Aggiungere un palloncino ossigeno attraverso il setto; questa mantiene una pressione positiva di ossigeno nell&#39;atmosfera sulla reazione. </li><li> Irradiare la miscela di reazione con una lampada da 23 watt. </li><li> Controllare l&#39;avanzamento della reazione mediante cromatografia su strato sottile (TLC, utilizzando una miscela di esano / acetato di etile in rapporto 70:30, il valore f R delle idroperossidi qui descritti è compreso tra 0,2 e 0,3) o da 1 H NMR da una campione prelevato (evapora il solvente su un evaporatore rotante e disciogliere il residuo in DMSO-d6). I tempi di reazione possono variare a seconda della sorgente di luce e la purezza del materiale di partenza, come già in parte 1.1. In generale, l&#39;integrale conversione delle tetrahydrocarbazoles 1 richiede 3 ore. </li><li> Filtrare il solido precipitato dopo la completa conversione del materiale di partenza. Lavaggio del solido può essere fatta con pentano per rimuovere la maggior parte deiil toluene, ma non è necessario per la purificazione. </li><li> Essiccare il solido isolato sotto pressione ridotta. </li></ol> ATTENZIONE: Anche se non abbiamo mai sperimentato alcun problema a lavorare con o manipolazione dei composti descritti in questo lavoro, le precauzioni devono essere prese quando si lavora con perossidi. In particolare, dovrebbe essere evitato il più possibile esporre perossidi pulito per riscaldare o per mescolarle con metalli o sali metallici. Esibirsi tali reazioni dietro uno scudo esplosione è raccomandato. . 2 Giunto Reazione - Metodo A Utilizzo 10 mol% acido trifluoroacetico in metanolo <ol><li> Pesare il idroperossido (0,49 mmol, 1,0 equiv. Dal punto 1) e il nucleofilo desiderato anilina (0,49 mmol, 1,0 equiv.) In una fiala di 12 ml o un pallone a fondo tondo adatto. </li><li> Aggiungere 10 ml di metanolo e successivamente 3,74 ml di acido trifluoroacetico (TFA, 0,049 mmol, 0.1 equiv.) Per flaconcino o pallone a fondo tondo. </li><li> Chiudere il contenitore con un tappo eagitare la miscela di reazione a temperatura ambiente per 4 ore. Variante workup A1 (per i prodotti che precipitano nel corso della reazione): </li><li> Filtrare il solido precipitato per ottenere il prodotto desiderato. Lavare il prodotto con metanolo (3 x 0,5 ml). </li><li> Per ottenere una seconda frazione di prodotto, si evapora il metanolo dal filtrato. Sciogliere il prodotto grezzo in 5 ml di acetato di etile a 40 ° C, poi raffreddare a temperatura ambiente e aggiungere 3-5 ml di pentano Il prodotto puro precipita. </li><li> Combinare le diverse frazioni di prodotto e asciugare sotto alto vuoto. Variante iter A2 (per i prodotti che non precipitano): </li><li> Si evapora il solvente subito dopo la reazione utilizzando un evaporatore rotante e purificare il residuo mediante cromatografia su colonna come specificato (gel di silice, esano / acetato di etile / trietilammina) per ottenere il prodotto desiderato. </li></ol> 3 Coupling Reaction -. Metodo BCon acido acetico <ol><li> Pesare il idroperossido (0,49 mmol, 1,0 equiv. Dal punto 1) e il nucleofilo desiderato anilina (0,49 mmol, 1,0 equiv.) In una fiala di 12 ml o un pallone a fondo tondo adatto. </li><li> Aggiungere 10 ml di acido acetico (AcOH) relativa alla fiala o pallone a fondo tondo. </li><li> Chiudere il contenitore con un tappo e agitare la miscela di reazione a temperatura ambiente per 4 ore. Variante workup B1 (per i prodotti che precipitano nel corso della reazione): </li><li> Filtrare il solido precipitato per ottenere il prodotto desiderato. Lavare il prodotto con AcOH (3 x 0,5 ml). </li><li> Per ottenere una seconda frazione di prodotto, evaporare l&#39;acido acetico dal filtrato. Sciogliere il prodotto grezzo in 5 ml di acetato di etile a 40 ° C, poi raffreddare a temperatura ambiente e aggiungere 3-5 ml di pentano Il prodotto puro precipita. </li><li> Combinare le diverse frazioni di prodotto e asciugare sotto alto vuoto. Variante Workup B2 </strong&gt; (per i prodotti che non precipitano): </li><li> Si evapora il solvente subito dopo la reazione utilizzando un evaporatore rotante e purificare il residuo mediante cromatografia su colonna come specificato (gel di silice, esano / acetato di etile / trietilammina) per ottenere il prodotto desiderato. </li></ol>

<ol>
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In sintesi, potremmo dimostrare che un legame CH in tetrahydrocarbazoles può essere comodamente funzionalizzato per generare prodotti CN-accoppiamento in una procedura in due fasi. Il primo passo è un noto ossidazione photocatalyzed di tetrahydrocarbazole (1) o suoi derivati ​​con ossigeno elementare 17,19, dando un idroperossido 2. Se eseguita in toluene, i prodotti idroperossido precipitano e possono essere convenientemente isolati mediant...

La funzionalizzazione diretta di legami CH è un obiettivo importante e in piedi a lungo in chimica organica 1. Tali trasformazioni possono essere molto potenti per snellire sintesi salvando passi, tempo e materiale rispetto ai metodi convenzionali che richiedono l&#39;introduzione e la rimozione di attivare o dirigere gruppi. Pertanto, la funzionalizzazione di legami CH è anche interessante per la chimica verde 2. In condizioni di ossidazione, due legami CH o un CH e un legame eteroatomo-H può essere trasformato in legami CC e C-eteroatomo, rispettivamente (Figura 1) 3-9. Spesso queste reazioni di accoppiamento ossidativo richiedono ossidanti sintetici, catalizzatori costosi o alte temperature. Pertanto, molti tentativi di sviluppare metodi che utilizzano catalizzatori economici, condizioni benigne e ossigeno o aria come ossidante morsetto 10. <img alt="Figura 1" fo:content-width = &quot;5in&quot; src = &quot;/ files/ftp_upload/51504/51504fig1highres.jpg&quot; width = &quot;500&quot; /&gt; Figura 1. Reazioni di accoppiamento ossidativo. <a href="https://www.jove.com/files/ftp_upload/51504/51504fig1highres.jpg" target="_blank">cliccate qui per vedere una versione più grande di questa figura.</a> Molti composti organici reagiscono lentamente con l&#39;ossigeno dall&#39;aria in reazioni di autossidazione che può funzionalizzare legami CH inserendo efficacemente O 2, formando una porzione idroperossido 11,12. Processi di autossidazione sono utilizzati su scala industriale di composti ossigenati generati da cariche idrocarburiche, ma autossidazione è anche un processo indesiderato se porta alla decomposizione di composti o materiali pregiati. In alcuni casi, ad esempio etere etilico, idroperossidi formate in aria possono anche essere esplosivi. Recentemente, abbiamo scoperto una reazione che utilizza un autossidazione per formare un nuovo legame CC da legami CH, senza necessità di un redox-attiva catalizzatore 13,14 </sup&gt;. Semplicemente mescolando i substrati sotto ossigeno in presenza di un catalizzatore acido porta alla formazione dei nuovi prodotti. Chiave per la reazione è la formazione di idroperossidi facile intermedi, che vengono sostituiti con il secondo substrato mediante catalisi acida 15. La reazione, tuttavia, è limitato a xanthene e alcuni composti correlati che vengono facilmente ossidati sotto una atmosfera di ossigeno ed i prodotti hanno applicazioni finora non trovati. Tuttavia ispirato da questa scoperta, abbiamo sviluppato un metodo di accoppiamento ossidativo correlati che utilizza il principio della CH funzionalizzazione via perossidi intermedi (chips) di sintetizzare derivati ​​farmacologicamente attive indolici 16. Indoli, soprattutto tetrahydrocarbazoles 1, può essere facilmente ossidato a idroperossidi 2 in presenza di ossigeno singoletto 17-19, che può essere generato utilizzando un sensibilizzante e luce visibile 20. A hydrporzione operoxide potrebbero servire come un gruppo uscente, se attivato da catalisi acida e consentire l&#39;introduzione di un nucleofilo 21,22. Idroperossidi sono anche noti per sottoporsi acido catalizzata reazioni di riarrangiamento come utilizzato nella sintesi industriale del fenolo da cumene, il processo Hock 23. Con attenti studi di ottimizzazione, siamo riusciti a trovare le condizioni per favorire la reazione di sostituzione desiderata con N-nucleofili come aniline 3 oltre i percorsi di decomposizione indesiderate riarrangiamento 16. Qui, descriviamo questa procedura CHIPS due fasi in dettaglio, utilizzando solo la luce visibile, un sensibilizzatore, ossigeno e acido. Tra i prodotti selezionati sono derivati ​​indolici 4, che mostrano elevata attività antivirale o inibiscono il fattore di crescita vascolare endoteliale (VGF), che può essere importante per la terapia tumorale 24-26.

<table border="0" cellpadding="0" cellspacing="0" width="797">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1,2,3,4-Tetrahydrocarbazole</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td style="width:151px;">T12408</td>
			<td style="width:291px;">If coloured, purification may be necessary. See Protocol 1.1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Methanol</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td>322415</td>
			<td>99.8% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4-Nitroaniline</td>
			<td style="width:139px;">Acros Organics</td>
			<td>128371000</td>
			<td>99% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trifluoroacetic acid</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td>T6508</td>
			<td>99% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Acetic acid</td>
			<td style="width:139px;">J. T. Baker</td>
			<td style="width:151px;">JTB RS 426960101</td>
			<td>99-100% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Aniline</td>
			<td style="width:139px;">Merck</td>
			<td>8222560100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">4-Aminobenzonitrile</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td>147753</td>
			<td>98% purity</td>
		</tr>
	</tbody>
</table>

synthesis of antiviral tetrahydrocarbazole derivatives by photochemical and acid-catalyzed c-h functionalization via intermediate peroxides (chips)

The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order to streamline synthesis by saving steps, time and material compared to conventional methods that require the introduction and removal of activating or directing groups. Therefore, the functionalization of C-H bonds is also attractive for green chemistry. Under oxidative conditions, two C-H bonds or one C-H and one heteroatom-H bond can be transformed to C-C and C-heteroatom bonds, respectively. Often these oxidative coupling reactions require synthetic oxidants, expensive catalysts or high temperatures. Here, we describe a two-step procedure to functionalize indole derivatives, more specifically tetrahydrocarbazoles, by C-H amination using only elemental oxygen as oxidant. The reaction uses the principle of C-H functionalization via Intermediate PeroxideS (CHIPS). In the first step, a hydroperoxide is generated oxidatively using visible light, a photosensitizer and elemental oxygen. In the second step, the N-nucleophile, an aniline, is introduced by Br&#248;nsted-acid catalyzed activation of the hydroperoxide leaving group. The products of the first and second step often precipitate and can be conveniently filtered off. The synthesis of a biologically active compound is shown.

Sintesi di 1 - (5-nitroindolin-1-il) -2,3,4,9-tetraidro-1H-carbazolo (4a): Sintetizzata secondo il Procedimento A, R f = (esano / acetato di etile 70:30) 0.63. Purificazione: Purificare il prodotto utilizzando il metodo A, variante iter A1 (i punti 2.4, 2.5, 2.6). Arancione solido, Resa: 95%. 1 H NMR (500 MHz, DMSO-d6): δ 10.90 (s, 1H),...

Watch this Scientific Journal Video about Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS at JoVE.com

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS

A two-step procedure for the synthesis of pharmaceutically active indole-derivatives by C-H functionalization with anilines is described, using photo- and Br&#248;nsted acid catalysis.

Sintesi di derivati ​​antivirale Tetrahydrocarbazole da fotochimica e acido-catalizzata CH funzionalizzazione via intermedi perossidi (CHIPS)

The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order ...

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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

Unit 1

Acids and Bases

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13.7K Views.  Max-Planck-Institut fuer Kohlenforschung. A two-step procedure for the synthesis of pharmaceutically active indole-derivatives by C-H functionalization with anilines is described, using photo- and Brønsted acid catalysis.

Video: Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS

Anticancer Metal Complexes: Synthesis and Cytotoxicity Evaluation by the MTT Assay

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; therefore their preparation should be conducted under an inert atmosphere. Evaluation of the anticancer activity of these complexes can be achieved by the MTT assay.
The MTT assay is a colorimetric viability assay based on enzymatic reduction of the MTT molecule to formazan when it is exposed to viable cells. The outcome of the reduction is a color change of the MTT molecule. Absorbance measurements relative to a control determine the percentage of remaining viable cancer cells following their treatment with varying concentrations of a tested compound, which is translated to the compound anticancer activity and its IC50 values. The MTT assay is widely common in cytotoxicity studies due to its accuracy, rapidity, and relative simplicity.
Herein we present a detailed protocol for the synthesis of air sensitive metal based drugs and cell viability measurements, including preparation of the cell plates, incubation of the compounds with the cells, viability measurements using the MTT assay, and determination of IC50 values.

A method for synthesis of air-sensitive titanium and vanadium anticancer agents is described, along with the evaluation of their cytotoxic activity towards human cancer cell line by the MTT Assay.

Antitumorali metallo Complessi: Sintesi e citotossicità valutazione da parte del saggio MTT

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; ...

Ricerca

Chimica

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Sintesi, Caratterizzazione, e funzionalizzazione di ibrida UA / CdS e Au / ZnS core / shell nanoparticelle

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of trifluoromethoxylated aromatic compounds remains a formidable challenge in organic synthesis. Conventional approaches often suffer from poor substrate scope, or require use of highly toxic, difficult-to-handle, and/or thermally labile reagents. Herein, we report a user-friendly protocol for the synthesis of methyl 4-acetamido-3-(trifluoromethoxy)benzoate using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II). Treating methyl 4-(N-hydroxyacetamido)benzoate (1a) with Togni reagent II in the presence of a catalytic amount of cesium carbonate (Cs2CO3) in chloroform at RT afforded methyl 4-(N-(trifluoromethoxy)acetamido)benzoate (2a). This intermediate was then converted to the final product methyl 4-acetamido-3-(trifluoromethoxy)benzoate (3a) in nitromethane at 120 &#176;C. This procedure is general and can be applied to the synthesis of a broad spectrum of ortho-trifluoromethoxylated aniline derivatives, which could serve as useful synthetic building blocks for the discovery and development of new pharmaceuticals, agrochemicals, and functional materials.

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

An operationally simple procedure for the synthesis of ortho-trifluoromethoxylated aniline derivatives via a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxyacetamide followed by thermally induced intramolecular OCF3-migration is reported.

Protocollo per la sintesi di<em&gt; Ortho</em&gt; Derivati ​​all&#39;anilina -trifluoromethoxylated

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution. In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotube particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. This method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.

A method for the functionalization of carbon nanotubes with structure-tunable polymeric encapsulation layers and structural characterization using small-angle neutron scattering is presented.

Funzionalizzazione di single-walled nanotubi di carbonio con termo-reversibili Block Copolimeri e caratterizzazione da piccolo angolo Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

Sintesi di proteine ​​bioconiugati<em&gt; via</em&gt; Chimica cisteina-maleimmide

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

Sintesi di nanofili Au associato a substrato tramite un meccanismo di crescita superficiale attiva

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Disaccharide nucleosides, which consist of disaccharide and nucleobase moieties, have been known as a valuable group of natural products having multifarious bioactivities. Although chemical O-glycosylation is a commonly beneficial strategy to synthesize disaccharide nucleosides, the preparation of substrates such as glycosyl donors and acceptors requires&#160;tedious protecting&#160;group manipulations and a purification at each synthetic step. Meanwhile, several research groups have reported that boronic and borinic esters serve as a protecting or activating group of carbohydrate derivatives to achieve the regio- and/or stereoselective acylation, alkylation, silylation, and glycosylation. In this article, we demonstrate the procedure for the regioselective O-glycosylation of unprotected ribonucleosides utilizing boronic acid. The esterification of 2&#39;,3&#39;-diol of ribonucleosides with boronic acid makes the temporary protection of diol, and, following O-glycosylation with a glycosyl donor in the presence of p-toluenesulfenyl chloride and silver triflate, permits the regioselective reaction of the 5&#39;-hydroxyl group to afford the disaccharide nucleosides. This method could be applied to various nucleosides, such as guanosine, adenosine, cytidine, uridine, 5-metyluridine, and 5-fluorouridine. This article and the accompanying video represent&#160;useful (visual) information for the O-glycosylation of unprotected nucleosides and their analogs for the synthesis of not only disaccharide nucleosides, but also a variety of biologically relevant derivatives.

Regioselective O-Glycosylation of Nucleosides via the Temporary 2&#039;,3&#039;-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Here, we present protocols for the synthesis of disaccharide nucleosides by the regioselective O-glycosylation of ribonucleosides via a temporary protection of their 2&#39;,3&#39;-diol moieties utilizing a cyclic boronic ester. This method applies to several unprotected nucleosides such as adenosine, guanosine, cytidine, uridine, 5-methyluridine, and 5-fluorouridine to give corresponding disaccharide nucleosides.

Regioselettiva O- glicosilazione dei nucleosidi tramite il temporaneo 2', 3'-diolo protezione da boronico per la sintesi di disaccaride nucleosidi

Disaccharide nucleosides, which consist of disaccharide and nucleobase moieties, have been known as a valuable group of natural products having ...

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. Recently, we have developed a two-step strategy for ketone enolate umpolung that has enabled the development of methods for chlorination, azidation, and amination using azoles. In addition, we have developed C-C bond&#8211;forming arylation and allylation reactions. At the heart of these methods is the preparation of the intermediate and highly reactive enolonium species prior to addition of a reactive nucleophile. This strategy is thus reminiscent of the preparation and use of metal enolates in classical synthetic chemistry. This strategy allows the use of nucleophiles that would otherwise be incompatible with the strongly oxidizing hypervalent iodine reagents. In this paper we present a detailed protocol for chlorination, azidation, N-heteroarylation, arylation, and allylation. The products include motifs prevalent in medicinally active products. This article will greatly assist others in using these methods.

A two step one-pot protocol for the umpolung of ketone enolates to enolonium species and addition of a nucleophile to the &#945;-position is described. Nucleophiles include chloride, azide, azoles, allyl-silanes, and aromatic compounds.

Un protocollo in due fasi per Umpolung funzionalizzazione di chetoni Via Enolonium le specie

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. ...

Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategies do not permit to exploit the properties of the MOF already available and it is imperative to find new methods to enhance the stability of MOFs in water while keeping their properties intact. Herein, we report a novel method to enhance the water stability of MOF crystals featuring Cu2(O2C)4&#160;paddle-wheel units, such as HKUST (where HKUST stands for Hong Kong University of Science &#38; Technology), with the catechols functionalized with alkyl and fluoro-alkyl chains. By taking advantage of the unsaturated metal sites and the catalytic catecholase-like activity of CuII ions, we are able to create robust hydrophobic coatings through the oxidation and subsequent polymerization of the catechol units on the surface of the crystals under anaerobic and water-free conditions without disrupting the underlying structure of the framework. This approach not only affords the material with improved water stability but also provides control over the function of the protective coating, which enables the development of functional coatings for the adsorption and separations of volatile organic compounds. We are confident that this approach could also be extended to other unstable MOFs featuring open metal sites.

Robust functional catechol coatings were produced in one step by direct reaction of the material known as HKUST with synthetic catechols under anaerobic conditions. The formation of homogeneous coatings surrounding the entire crystal is ascribed to the biomimetic catalytic activity of Cu(II) dimers on the external surface of the crystals.

Funzionalizzazione superficiale di Metal-Organic Frameworks per resistenza all'umidità migliorata

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. ...

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the reaction is commonly performed using chlorinated or amide solvent systems, which are hazardous to human health and the environment. Our methodology utilizes acetonitrile as a greener and less hazardous solvent system. This protocol exhibits rates and yields that are comparable to traditional solvent systems and employs an extraction and wash sequence that eliminates the need for the purification of the ester product via column chromatography. This general method can be used to couple a variety of carboxylic acids with 1&#176; and 2&#176; aliphatic alcohols, benzylic and allylic alcohols, and phenols to obtain pure esters in high yields. The goal of the protocol detailed here is to provide a greener alternative to a common esterification reaction, which could serve useful for ester synthesis in both academic and industrial applications.

A modified Steglich esterification reaction was used to synthesize a small library of ester derivatives with primary and secondary alcohols. The methodology uses a non-halogenated and greener solvent, acetonitrile, and enables product isolation in high yields without the need for chromatographic purification.

Sintesi degli esteri tramite un'esterificazione Steglich più verde in Acetonitrile

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the ...

Sintesi di derivati ​​antivirale Tetrahydrocarbazole da fotochimica e acido-catalizzata CH funzionalizzazione via intermedi perossidi (CHIPS)

Sintesi di derivati antivirale Tetrahydrocarbazole da fotochimica e acido-catalizzata CH funzionalizzazione via intermedi perossidi (CHIPS)