Name: one-pot microwave-assisted conversion of anomeric nitrate-esters to trichloroacetimidates
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Description: Watch this Scientific Journal Video about One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates at JoVE.com

Gli autori si desidera ringraziare Vanderbilt University e l'Istituto di biologia chimica per il sostegno finanziario. Signor Berkley Ellis e Prof John McLean sono riconosciuti per l'analisi spettrale di massa ad alta risoluzione.

1. rappresentante microonde-assistita denitrazione
<ol><li>Posizionare l'estere di nitrato azido (1.0 equiv., 0,2 mmol) in un flaconcino di reazione di 8 mL forno a microonde. La scala della reazione può essere aumentata a parecchi mmol senza alcun effetto negativo sui progressi di reazione.</li>
	<li>Sciogliere l'estere azido-nitrato in 20% AQ. acetone (0,1 M, 2,0 mL). Aggiungere piridina (5,0 equiv., 0,08 mL, 1,0 mmol) il recipiente di reazione. Tappo del flaconcino di irradiazione a microonde e posizionare il recipiente di reazione in una cavità di reattore a microonde.</li>
	<li>Irradiare la soluzione a 120 ° C per 15 minuti con agitazione e con un tempo di tenuta fisso. Il tempo di attesa rappresenta quanto tempo si verificherà l'irradiazione all'area temperatura e la pressione risultante. Riscaldare tutte le reazioni alla temperatura segnalata per un periodo di 2 minuti in rampa. Monitorare la temperatura di un sensore incorporato IR.</li>
	<li>Dopo 15 min, analizzare la miscela di reazione mediante cromatografia su strato sottile (TLC) per confermare il consumo del materiale di partenza. Utilizzare 1:1. acetato di etile/esano come eluente.<ol>
<li>Visualizzare la piastra di TLC usando Ciociola ammonio molybate macchia. Rf del reagente e del prodotto può variare, ma l'alcol riducente è generalmente da 0.05 a 0.1 inferiore Rf più reattivo.</li>
	</ol>
</li>
</ol>2. formazione della trichloroacetimidate
<ol><li>A seguito di consumo completo del materiale di partenza, far evaporare il solvente per un volume ridotto utilizzando una compagnia aerea. Diluire con (diclorometano) CH2Cl2 (1,0 mL), quindi utilizzare una siringa per rimuovere lo strato di acqua. Una volta rimosso lo strato di acqua, raffreddare la miscela di reazione a 0 ° C, usando un bagno di acqua e ghiaccio.</li>
	<li>Successivamente, aggiungere DBU (eq 10, 0,3 mL, 1,9 mmol) e 2,2,2-trichloroacetonitrile (50 eq, 1,0 mL, 10 mmol) per il recipiente di reazione. Entrambi i reagenti sono aggiunti in eccesso e sono necessari un minimo di 1 equivalente di base e 1 equivalente di 2,2,2-trichloroacetonitrile.</li>
	<li>Lasciare che la miscela di reazione mescolare durante il riscaldamento a temperatura ambiente. Monitorare la reazione di TLC per confermare il consumo del materiale di partenza.<ol>
<li>Utilizzare 1:1. acetato di etile/esano come eluente. Visualizzare la piastra di TLC usando Ciociola ammonio molybate macchia. Rf del reagente e del prodotto varierà.</li>
	</ol>
</li>
	<li>Dopo il consumo completo del materiale di partenza, trasferire la miscela di reazione in un pallone di recupero e concentrare la miscela sotto vuoto a 30 ° C. Evaporazione del solvente fornirà grezzo da giallo pallido a marrone olio.</li>
	<li>Purificare il prodotto grezzo da cromatografia su colonna di gel di silice con una colonna di cromatografia di 1,5 cm e 1:4. acetato di etile/esano come eluente. La forma fisica dell'immina varierà da molecola per molecola.</li>
</ol><img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56610/56610fig1v3.jpg"> Figura 1. Esempi rappresentativi della conversione degli esteri 2-azido-1-nitrato di uno-pentola per 2-azido-1-trichloroimidates. <a href="//cloudflare.jove.com/files/ftp_upload/56610/56610fig1v3large.jpg" target="_blank">Clicca qui per visualizzare una versione più grande di questa figura.</a>

<ol>
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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+the+laboratory+to+the+clinic:+A+retrospective+on+fully+synthetic+carbohydrate-based+anticancer+vaccines.">From the laboratory to the clinic: A retrospective on fully synthetic carbohydrate-based anticancer vaccines.</a> Angew. Chem. Int. Ed. Engl. 39 (5), 836-863 (2000).</li><li>Nicolaou, K. C., Hale, C. R. H., Nilewski, C., Ioannidou, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Constructing+molecular+complexity+and+diversity:+total+synthesis+of+natural+products+of+biological+and+medicinal+importance.">Constructing molecular complexity and diversity: total synthesis of natural products of biological and medicinal importance.</a> Chemical Society Reviews. 41 (15), 5185-5238 (2012).</li><li>Zhu, X., Schmidt, R. 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E., Ottosson, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Armed-Disarmed+Effects+in+Glycosyl+Donors+-+Rationalization+and+Sidetracking.">Armed-Disarmed Effects in Glycosyl Donors - Rationalization and Sidetracking.</a> J. Org. Chem. 55 (25), 6068-6070 (1990).</li><li>Bohe, L., Crich, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+propos+of+glycosyl+cations+and+the+mechanism+of+chemical+glycosylation;+the+current+state+of+the+art.">A propos of glycosyl cations and the mechanism of chemical glycosylation; the current state of the art.</a> Carbohydr. 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Il protocollo descritto in questo tutorial fornisce un metodo per convertire nitrato esteri alla funzionalità utili, reattiva. In senso più ampio, impiegando un reattore a microonde per la realizzazione di manovre specifiche nel corso di una sintesi di carboidrati ha il potenziale per fare trasformazioni difficile facile e di routine. Il nostro obiettivo in questo tutorial è per illustrare come gestire i carboidrati nel contesto di irradiazione a microonde.
Nel caso la reazione del padre, i...

A causa della loro ubiquità nella biologia molecolare, carboidrati sono stati gli obiettivi di lunga data per sintesi chimica. 1 , 2 , 3 alla base di qualsiasi successo campagna sintetico è la corretta distribuzione delle reazioni di glicosilazione per costruire la catena oligosaccaride. 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 non sorprendentemente, ci sono un gran numero di metodi per installare legami glicosidici. 13 , 14 the Koenigs-Knorr metodo è una delle prime procedure note e coinvolge un glicosil cloruro o bromuro di accoppiamento con una componente alcolica, solitamente sotto l'attivazione di metalli pesanti (mercurio o argento). 15 correlate glicosil fluoruri sono stati introdotti come donatori nel 1981 dal gruppo Mukaiyama e hanno trovato applicazione diffusa a causa della loro maggiore stabilità termica e chimica. 16 all'estremità opposta dello spettro reattività sono glicosil ioduri, che sono molto più reattivi rispetto gli altri alogenuri. Maggiore reattività è accompagnata da aumento STEREOCONTROLLO, particolarmente quando formando oligosaccaridi α-collegati. 17 oltre a "haloglycosides", thioglycosides hanno trovato ampia utilità, in parte, grazie alla loro facilità di formazione, stabilità ad una moltitudine di condizioni di reazione e l'attivazione con reagenti elettrofili. 18
I metodi descritti sopra messa a fuoco sulla conversione di un alcool anomerica per un "non-ossigeno" contenente, lasciando il gruppo che è attivato e in definitiva spostata di un alcool da una molecola accettore latente. Attivazione dell'ossigeno anomerico come descritto dalla scuola Schmidt, si concentra sulla conversione dell'ossigeno di C1 stesso, in un gruppo uscente. 19 questo metodo è il più potente e ampiamente utilizzati nelle reazioni di glicosilazione chimica. Trichloroacetimidate donatori sono prontamente preparati da una riduzione di zucchero e trichloroacetonitrile in presenza di una base come carbonato di potassio (K2CO3) o 1,8-diazabiciclo [5.4.0] undec-7-ene (DBU). Queste specie sono quindi attivate usando acidi di Lewis. 20
Recentemente, abbiamo riferito che i donatori 2-azido-1-trichloroacetimidate possono essere preparati direttamente da glicali. Il processo comporta una reazione di due, uno-pentola procedura dagli esteri 2-azido-1-nitrato. 21 questo protocollo dettagliato è destinato per aiutare i praticanti a completare con successo la trasformazione nell'alto rendimento. Di particolare interesse è il primo passo della sequenza, che si concentra su denitrazione termica sotto forno a microonde - assistita riscaldamento. Speriamo anche di fornire un tutorial visual su impiegando reattori di microonde nella sintesi organica.

<table><tbody><tr><td>230 400 mesh silica gel</td><td>SiliCycle Inc</td><td>R10030B</td><td></td></tr><tr><td>TLC plates</td><td>SiliCycle Inc</td><td>TLG-R10014B-527</td><td></td></tr><tr><td>Ceric ammonium molybdate</td><td>Sigma-Aldrich</td><td>A1343</td><td></td></tr><tr><td>Solvent Still</td><td>Mbraun</td><td>MB-SPS-800</td><td></td></tr><tr><td>Infared spectrometer</td><td>Thermo</td><td>Thermo Electron IR100</td><td></td></tr><tr><td>Nuclear Magnetic Resonance</td><td>Bruker</td><td></td><td>400, 600 MHz</td></tr><tr><td>LC/MS</td><td>Thermo/Dionex</td><td></td><td>Single quad, ESI</td></tr><tr><td>HRMS</td><td>Agilent</td><td>Synapt G2 S HDMS</td><td></td></tr><tr><td>Microwave reactor</td><td>Anton Parr</td><td>Anton Parr G10 Monowave 200</td><td></td></tr><tr><td>DBU</td><td>Sigma-Aldrich</td><td>139009</td><td></td></tr><tr><td>CCl&lt;sub&gt;3&lt;/sub&gt;CN</td><td>Sigma-Aldrich</td><td>T53805</td><td></td></tr><tr><td>Pyridine</td><td>Sigma-Aldrich</td><td>270970</td><td></td></tr><tr><td>Acetone</td><td>Fisher Scientific</td><td>A18-20</td><td>Tech. grade</td></tr><tr><td>Phase separator</td><td>Biotage</td><td>120-1901-A</td><td></td></tr><tr><td>Rotary evaporator</td><td>Buchi</td><td>R-100</td><td></td></tr></tbody></table>

one-pot microwave-assisted conversion of anomeric nitrate-esters to trichloroacetimidates

L'obiettivo della seguente procedura è quello di fornire una dimostrazione della conversione di un donatore di glicosil trichloroacetimidate uno-pentola di un 2-azido-1-nitrato-estere. In seguito azido-nitrazione di un glycal, l'estere 2-azido-1-nitrato di prodotto può essere idrolizzato sotto irradiazione assistita da microonde. Questa trasformazione avviene solitamente utilizzando reagenti fortemente nucleofili e lunghi tempi di reazione. Irradiazione a microonde induce idrolisi, in assenza di reagenti, con brevi tempi di reazione. A seguito di denitrazione, l'alcool anomerica intermedio viene convertito, nella stessa pentola, per il corrispondente 2-azido-1-trichloroacetimidate.

La tecnologia descritta nel presente documento è stata dimostrata su un pool di tre 2-azido-1-nitrato esteri. In ogni caso il primo passo della reazione era completo entro 20 minuti.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56610/56610fig2v3.jpg"> Figura 2. Esempio rappresentativo di idrolisi (1 ->2) e la conversione di uno-pentola di estere 2-azido-1-nitra...

Watch this Scientific Journal Video about One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates at JoVE.com

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates

One-pot assistita da microonde conversione di anomerica nitrato-esteri Trichloroacetimidates

Un 2-azido-1-nitrato-estere può essere convertito per il corrispondente 2-azido-1-trichloroacetimidate in una routine di uno-pentola. L'obiettivo del manoscritto è di dimostrare l'utilità del reattore a microonde nella sintesi di carboidrati.

The goal of the following procedure is to provide a demonstration of the one-pot conversion of a 2-azido-1-nitrate-ester to a trichloroacetimidate ...

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7.4K Views.  Vanderbilt University. Un 2-azido-1-nitrato-estere può essere convertito per il corrispondente 2-azido-1-trichloroacetimidate in una routine di uno-pentola. L'obiettivo del manoscritto è di dimostrare l'utilità del reattore a microonde nella sintesi di carboidrati.

Video: One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates

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.

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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Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form catalytically active N-Heterocyclic Carbenes (NHCs). Here we have used ILs as precatalysts in the addition of &#945;,&#946;-unsaturated aldehydes to chalcones to form 1,6-ketoesters, incorporating an anti-diphenyl moiety in a highly stereoselective fashion. The reaction has a broad substrate scope and several functional groups and heteroaromatics can be integrated into the ketoester backbone in generally good yields with maintained stereoselectivity. The reaction protocol is robust and scalable. The starting materials are inexpensive and the products can be obtained after simple filtration, avoiding solvent-demanding chromatography. Furthermore, the IL can be recycled up to 5 times without any loss of reactivity. Moreover, the 1,6-ketoester end product is a potent gelator in several hydrocarbon based solvents. The method enables rapid access to and evaluation of a new class of low molecular weight gelators (LMWGs) from recyclable and inexpensive starting materials.

Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents.

Sintesi altamente stereoselettiva di 1,6-chetoesteri Mediata da liquidi ionici: una reazione a tre componenti Abilitazione accesso rapido a una nuova classe di basso peso molecolare Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form ...

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 ...

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high atomic and step economy. However, this functionality-directed cross-coupling reaction has not been developed, as there are still limited directing groups in practical use. In particular, a stoichiometric amount of oxidant is usually required, producing a large amount of waste. Due to our interest in novel 1,3-butadiene synthesis, we describe the ruthenium-catalyzed olefination of electron-deficient alkenes using allyl acetate and without external oxidant. The reaction of 2-phenyl acrylamide and allyl acetate was chosen as a model reaction, and the desired diene product was obtained in 80% isolated yield with good stereoselectivity (Z,E/Z,Z = 88:12) under optimal conditions: [Ru(p-cymene) Cl2]2 (3 mol %) and AgSbF6 (20 mol %) in DCE at 110 &#186;C for 16 h. With the optimized catalytic conditions in hand, representative &#945;- and/or &#946;-substituted acrylamides were investigated, and all reacted smoothly, regardless of aliphatic or aromatic groups. Also, differently N-substituted acrylamides have proven to be good substrates. Moreover, we examined the reactivity of different allyl derivatives, suggesting that the chelation of acetate oxygen to the metal is crucial for the catalytic process. Deuterium-labeled experiments were also conducted to investigate the reaction mechanism. Only Z-selective H/D exchanges on acrylamide were observed, indicating a reversible cyclometalation event. In addition, a kinetic isotope effect (KIE) of 3.2 was observed in the intermolecular isotopic study, suggesting that the olefinic C-H metalation step is probably involved in the rate-determining step.

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

The ruthenium-catalyzed olefination of electron-deficient alkenes with allyl acetate is described here. By using aminocarbonyl as a directing group, this external oxidant-free protocol has high efficiency and good stereo- and regioselectivity, opening a novel synthetic route to (Z,E)-butadiene skeletons.

Facile Preparazione di (2<em&gt; Z</em&gt;, 4<em&gt; E</em&gt;) - Dienamidi per l&#39;olefinazione di elettroni con deficit di elettroni con allil-acetato

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high ...

Preparation of N-(2-alkoxyvinyl)sulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines

Decomposition of N-tosyl-1,2,3-triazoles with rhodium(II) acetate dimer in the presence of alcohols forms synthetically versatile N-(2-alkoxyvinyl)sulfonamides, which react under a variety of conditions to afford useful N- and O-containing compounds. Acid-catalyzed addition of alcohols or thiols to N-(2-alkoxyvinyl)sulfonamide-containing phthalans provides access to ketals and thioketals, respectively. Selective reduction of the vinyl group in N-(2-alkoxyvinyl)sulfonamide-containing phthalans via hydrogenation yields the corresponding phthalan in good yield, whereas reduction with sodium bis(2-methoxyethoxy)aluminumhydride generates a ring-opened phenethylamine analogue. Because the N-(2-alkoxyvinyl)sulfonamide functional group is synthetically versatile, but often hydrolytically unstable, this protocol emphasizes key techniques in preparing, handling, and reacting these pivotal substrates in several useful transformations.

Preparation of N-2-alkoxyvinylsulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines

Representative experimental procedures for the synthesis of N-(2-alkoxyvinyl)sulfonamides and subsequent conversion to phthalan and phenethylamine derivatives are presented in detail.

Preparazione di N-(2-alkoxyvinyl) sulfamidici da N- tosyl-1, 2,3-triazoli e successiva conversione di Phthalans sostituito e fenetilamine

Decomposition of N-tosyl-1,2,3-triazoles with rhodium(II) acetate dimer in the presence of alcohols forms synthetically versatile ...

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides

The conjugate addition of organometallic reagents to &#945;,&#946;-unsaturated carbonyls represents an important method to generate C&#8211;C bonds in the preparation of all-carbon quaternary centers. Though conjugate additions of organometallic reagents are typically performed utilizing highly reactive organolithium or Grignard reagents, organozinc reagents have garnered attention for their enhanced chemoselectivity and mild reactivity. Despite numerous recent advances with more reactive diorganozinc and mixed diorganozinc reagents, the generation of all-carbon quaternary centers via the conjugate addition of functionalized monoorganozinc reagents remains a challenge. This protocol details a convenient and mild &#8220;one-pot&#8221; preparation and copper mediated conjugate addition of functionalized monoorganozinc bromides to cyclic &#945;,&#946;-unsaturated carbonyls to afford a broad scope of all-carbon quaternary centers in generally excellent yield and diastereoselectivity. Key to the development of this technology is the utilization of DMA as a reaction solvent with TMSCl as a Lewis acid. Notable advantages to this methodology include the operational simplicity of the organozinc reagent preparation afforded by the utilization of DMA as a solvent, as well as an efficient conjugate addition mediated by various Cu(I) and Cu(II) salts. Moreover, an intermediate silyl enol ether can be isolated utilizing a modified workup procedure. The substrate scope is limited to cyclic unsaturated ketones, and the conjugate addition is impeded by stabilized (e.g., allyl, enolate, homoenolate) and sterically encumbered (e.g., neopentyl, o-aryl) monoorganozinc reagents. Conjugate additions to five- and seven-membered rings were effective, albeit in lower yields compared with six-membered ring substrates.

A simple and practical protocol for the efficient conjugate addition of functionalized monoorganozinc bromides to cyclic &#945;,&#946;-unsaturated carbonyls to furnish all-carbon quaternary centers was developed.

Sintesi efficiente dei centri quaternari All-Carbon tramite l'aggiunta di coniugato di Monoorganozinc di bromide funzionalizzati

The conjugate addition of organometallic reagents to &#945;,&#946;-unsaturated carbonyls represents an important method to generate C&#8211;C bonds in the ...

Microwave-Assisted Preparation of 1-Aryl-1H-pyrazole-5-amines

A synthetic process for the preparation of a variety of 1-aryl-1H-pyrazole-5-amines was developed. The microwave-mediated nature of this method makes it efficient in both time and resources and utilizes water as the solvent. 3-Aminocrotononitrile or an appropriate &#945;-cyanoketone is combined with an aryl hydrazine and dissolved in 1 M HCl. The mixture is then heated in a microwave reactor at 150 &#176;C, typically for 10-15 min. The product can be readily obtained by basifying the solution with 10% NaOH and isolating the desired compound with a simple vacuum filtration. The use of water as a solvent in this reaction lends to its ease and utility in production, and this method is easily reproducible with a variety of functional groups. Typical isolated yields range from 70-90%, and reactions can be performed on the milligram to gram scale with little to no change in observed yields. Some of the applications of these molecules and their derivatives include pesticides, anti-malarials, and chemotherapeutics, among many others.

Microwave-Assisted Preparation of 1-Aryl-1H-pyrazole-5-amines

1-Aryl-1H-pyrazole-5-amines are prepared from aryl hydrazines combined with either 3-aminocrotononitrile or an &#945;-cyanoketone in a 1 M HCl solution using a microwave reactor. Most reactions are done in 10-15 minutes and pure product can be obtained via vacuum filtration with typical isolated yields of 70-90%.

Preparazione a microonde di 1-Aryl-1H-pyrazole-5-ammine

A synthetic process for the preparation of a variety of 1-aryl-1H-pyrazole-5-amines was developed. The microwave-mediated nature of this method makes it ...

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyl(tropone)iron

aza-Michael adducts of tricarbonyl(tropone)iron are synthesized by two different methods. Primary aliphatic amines and cyclic secondary amines participate in a direct aza-Michael reaction with tricarbonyl(tropone)iron under solvent-free conditions. Less nucleophilic aniline derivatives and more hindered secondary amines add efficiently to the cationic tropone complex formed by protonation of tricarbonyl(tropone)iron. While the protocol utilizing the cationic complex is less efficient overall for accessing the aza-Michael adducts than the direct, solvent-free addition to the neutral complex, it allows the use of a broader range of amine nucleophiles. Following protection of the amine of the aza-Michael adduct as a tert-butyl carbamate, the diene is decomplexed from the iron tricarbonyl fragment upon treatment with cerium(IV) ammonium nitrate to provide derivatives of 6-aminocyclohepta-2,4-dien-1-one. These products can serve as precursors to diverse compounds containing a seven-membered carbocyclic ring. Because the demetallation requires protection of the amine as a carbamate, the aza-Michael adducts of secondary amines cannot be decomplexed using the protocol described here.

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyltroponeiron

Representative experimental procedures for the addition of amine nucleophiles to tricarbonyl(tropone)iron and subsequent demetallation of the resulting complexes are presented in detail.

Preparazione di 6-aminociclohepta-2,4-dien-1-one Derivati via Tricarbonyl(tropone)iron

aza-Michael adducts of tricarbonyl(tropone)iron are synthesized by two different methods. Primary aliphatic amines and cyclic secondary amines participate ...

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

CO2 transformations using a one-pot two-step method are presented herein. The purpose of the method is to give access to a variety of value-added products and notably to generate chiral carbon centers. The crucial first step consists in the selective double hydroboration of CO2 catalyzed by an iron hydride complex. The product obtained with this 4 e- reduction is a rare bis(boryl)acetal, compound 1, which is subjected in situ to three different reactions in a second step. The first reaction concerns a condensation reaction with (diisopropyl)phenylamine affording the corresponding imine 2. In the second and third reaction, intermediate 1 reacts with triazol-5-ylidene (Enders&#39; carbene) to afford compounds 3 or 4, depending on the reaction conditions. In both compounds, C-C bonds are formed, and chiral centers are generated from CO2 as the only source of carbon. Compound 4 exhibits two chiral centers obtained in a diastereoselective manner in a formose-type mechanism. We proved that the remaining boryl fragment plays a key role in this unprecedented stereocontrol. The interest of the method stands on the reactive and versatile nature of 1, giving rise to various complex molecules from a single intermediate. The complexity of a two-step method is compensated by the overall short reaction time (2 h for the larger reaction time), and mild reaction conditions (25 &#176;C to 80 &#176;C and 1 to 3 atm of CO2).

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

CO2 transformations are conducted in a one-pot two-step procedure for the synthesis of complex molecules. The selective 4 e- reduction of CO2 with a hydroborane reductant affords a reactive and versatile bis(boryl)acetal intermediate which is subsequently involved in condensation reaction or carbene-mediated C-C coupling generation.

Versatile trasformazioni di CO2 in prodotti complessi: una strategia in due fasi in un solo vaso

CO2 transformations using a one-pot two-step method are presented herein. The purpose of the method is to give access to a variety of value-added products ...

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

Heteroarylation introduces heteroaryl fragments to organic molecules. Despite the numerous available reactions reported for arylation via transition metal catalysis, the literature on direct heteroarylation is scarce. The presence of heteroatoms such as nitrogen, sulfur and oxygen often make heteroarylation a challenging research field due to catalyst poisoning, product decomposition and the rest. This protocol details a highly efficient direct &#945;-C(sp3) heteroarylation of ketones under microwave irradiation. Key factors for successful heteroarylation include the use of XPhos Palladacycle Gen. 4 Catalyst, excess base to suppress side reactions and the high temperature and pressure achieved in a sealed reaction vial under microwave irradiation. The heteroarylation compounds prepared by this method were fully characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR) and high-resolution mass spectrometry (HRMS). This methodology has several advantages over literature precedents including broad substrate scope, rapid reaction time, greener procedure and operational simplicity by eliminating the preparation of intermediates such as silyl enol ether. Possible applications for this protocol include, but are not limited to, diversity-oriented synthesis for the discovery of biologically active small molecules, domino synthesis for the preparation of natural products and ligand development for new transition metal catalytic systems.

Heteroaryl compounds are important molecules utilized in organic synthesis, medicinal and biological chemistry. A microwave-assisted heteroarylation using palladium catalysis provides a rapid and efficient method to attach heteroaryl moieties directly to ketone substrates.

Un'eteroarylazione diretta a microonde di chetoni utilizzando la catalisi metallica di transizione

Heteroarylation introduces heteroaryl fragments to organic molecules. Despite the numerous available reactions reported for arylation via transition metal ...

One-pot assistita da microonde conversione di anomerica nitrato-esteri Trichloroacetimidates

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

Sintesi altamente stereoselettiva di 1,6-chetoesteri Mediata da liquidi ionici: una reazione a tre componenti Abilitazione accesso rapido a una nuova classe di basso peso molecolare Gelators

Protocollo per la sintesi di

Facile Preparazione di (2

Preparazione di N-(2-alkoxyvinyl) sulfamidici da N- tosyl-1, 2,3-triazoli e successiva conversione di Phthalans sostituito e fenetilamine

Sintesi efficiente dei centri quaternari All-Carbon tramite l'aggiunta di coniugato di Monoorganozinc di bromide funzionalizzati

Preparazione a microonde di 1-Aryl-1H-pyrazole-5-ammine

Preparazione di 6-aminociclohepta-2,4-dien-1-one Derivati via Tricarbonyl(tropone)iron

Versatile trasformazioni di CO₂ in prodotti complessi: una strategia in due fasi in un solo vaso

Un'eteroarylazione diretta a microonde di chetoni utilizzando la catalisi metallica di transizione

One-pot assistita da microonde conversione di anomerica nitrato-esteri Trichloroacetimidates

Riepilogo

Esplora Altri Video

Capitoli in questo video

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

Sintesi altamente stereoselettiva di 1,6-chetoesteri Mediata da liquidi ionici: una reazione a tre componenti Abilitazione accesso rapido a una nuova classe di basso peso molecolare Gelators

Protocollo per la sintesi di

Facile Preparazione di (2

Preparazione di N-(2-alkoxyvinyl) sulfamidici da N- tosyl-1, 2,3-triazoli e successiva conversione di Phthalans sostituito e fenetilamine

Sintesi efficiente dei centri quaternari All-Carbon tramite l'aggiunta di coniugato di Monoorganozinc di bromide funzionalizzati

Preparazione a microonde di 1-Aryl-1H-pyrazole-5-ammine

Preparazione di 6-aminociclohepta-2,4-dien-1-one Derivati via Tricarbonyl(tropone)iron

Versatile trasformazioni di CO2 in prodotti complessi: una strategia in due fasi in un solo vaso

Un'eteroarylazione diretta a microonde di chetoni utilizzando la catalisi metallica di transizione

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

Versatile trasformazioni di CO₂ in prodotti complessi: una strategia in due fasi in un solo vaso