Name: one-pot microwave-assisted conversion of anomeric nitrate-esters to trichloroacetimidates
Uploaded: 2018-01-15T13:00:00.000+00:00
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Yazarlar Vanderbilt Üniversitesi ve finansal destek için Kimya Biyoloji Enstitüsü kabul etmek istiyorum. Bay Berkley Ellis ve Prof. John McLean yüksek çözünürlüklü kitle spektral analiz için kabul vardır.

1. temsilcisi mikrodalga-kaslarda destekli
<ol><li>Azido nitrat ester yerleştirin (1.0 eşdeğeri, 0.2 mmol) 8 mL mikrodalga tepki şişe içinde. Ölçeğin reaksiyon reaksiyon ilerleme üzerinde herhangi bir olumsuz etkisi olmadan birkaç mmol artırılabilir.</li>
	<li>%20 AQ aseton (0.1 M, 2.0 mL) azido-nitrat ester geçiyoruz. Pyridine (5.0 eşdeğeri, 0,08 mL, 1.0 mmol) tepki taşıyıcıyı ekleyin. Mikrodalga ışınlama şişeyi kap ve reaksiyon taşıyıcıyı bir mikrodalga reaktör boşluk koyun.</li>
	<li>120 ° c 15 dakika karıştırarak ile ve bir sabit tutun zaman ile çözüm ışınlatayım. Tutun zaman ışınlama belirlenen sıcaklık ve sonuç basınç ne kadar gerçekleşir gösterir. Bildirilen sıcaklık bütün tepkiler bir 2 dakikalık bayiliği süre içinde ısı. Sıcaklık yerleşik IR algılayıcı tarafından izlemek.</li>
	<li>15 dk sonra başlangıç malzeme tüketiminin onaylamak için ince tabaka Kromatografi (TLC) kullanarak tepki karışımı analiz. 1:1 Etil asetat/hexanes eluent kullanın.<ol>
<li>TLC plaka ceric amonyum molybate leke kullanarak görselleştirmek. Kontrollerimiz ve ürün Rf değişir, ancak genel olarak 0,05-0,1 daha düşük Rf kontrollerimiz daha azalan bakiyeli alkol olduğunu.</li>
	</ol>
</li>
</ol>2. trichloroacetimidate oluşumu
<ol><li>Başlangıç materyali tam tüketiminin bir havayolu kullanarak düşük birim için solvent buharlaşır. O zaman, (diklorometan) CH2Cl2 (1.0 mL) sulandırmak ve bir şırınga su katmanı kaldırmak için kullanın. Bir kez su katmanı kaldırılır, 0 ° C bir buz-su banyosu kullanarak tepki karışıma serin.</li>
	<li>Sonra DBU (10 eq, 0.3 mL, 1.9 mmol) ve 2,2,2-trichloroacetonitrile (50 eq, 1.0 mL, 10 mmol) tepki taşıyıcıyı ekleyin. Her iki reaktif aşan eklenir ve en az 1 Bankası denk ve 2,2,2-trichloroacetonitrile 1 denk ihtiyaç vardır.</li>
	<li>Ortam sıcaklığı için Isınma sırasında karıştırmaya tepki karışım izin verin. Başlangıç malzeme tüketiminin onaylamak için TLC ile tepki izlemek.<ol>
<li>1:1 Etil asetat/hexanes eluent kullanın. TLC plaka ceric amonyum molybate leke kullanarak görselleştirmek. Kontrollerimiz ve ürün Rf değişir.</li>
	</ol>
</li>
	<li>Tam tüketimi malzeme başlayan sonra reaksiyon karışımı bir kurtarma şişesi aktarmak ve karışım olarak vacuo 30 ° C'de konsantre Ham bir soluk sarı kahverengi yağ çözücü buharlaşma sağlar.</li>
	<li>Ham ürün silika jel sütun Kromatografi ile 1,5 cm Kromatografi sütun ve 1:4 Etil asetat/hexanes tarafından eluent arındırmak. İmidate fiziksel şeklinde molekül molekül değişir.</li>
</ol><img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56610/56610fig1v3.jpg"> Şekil 1. 2-azido-1-trichloroimidates 2-azido-1-nitrat esterleri bir pot dönüşümünü temsilcisi örnekleri. <a href="//cloudflare.jove.com/files/ftp_upload/56610/56610fig1v3large.jpg" target="_blank">Bu rakam daha büyük bir versiyonunu görüntülemek için buraya tıklayınız.</a>

<ol>
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Ber. 34 (1), 957-981 (1901).</li><li>Mukaiyama, T., Murai, Y., Shoda, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Efficient+Method+for+Glucosylation+of+Hydroxy+Compounds+Using+Glucopyranosyl+Fluoride.">An Efficient Method for Glucosylation of Hydroxy Compounds Using Glucopyranosyl Fluoride.</a> Chem. Lett. (3), 431-432 (1981).</li><li>Meloncelli, P. J., Martin, A. D., Lowary, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glycosyl+iodides.+History+and+recent+advances.">Glycosyl iodides. History and recent advances.</a> Carbohydrate Research. 344 (9), 1110-1122 (2009).</li><li>Lian, G., Zhang, X., Yu, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thioglycosides+in+carbohydrate+research.">Thioglycosides in carbohydrate research.</a> Carbohydr. Res. 403, 13-22 (2015).</li><li>Schmidt, R. R., Kinzy, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anomeric-Oxygen+Activation+for+Glycoside+Synthesis+-+the+Trichloroacetimidate+Method.">Anomeric-Oxygen Activation for Glycoside Synthesis - the Trichloroacetimidate Method.</a> Advances in Carbohydrate Chemistry and Biochemistry. 50, 21-123 (1994).</li><li>Schmidt, R. R., Toepfer, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glycosylation+with+highly+reactive+glycosyl+donors:+efficiency+of+the+inverse+procedure.">Glycosylation with highly reactive glycosyl donors: efficiency of the inverse procedure.</a> Tetrahedron Lett. 32 (28), 3353-3356 (1991).</li><li>Keith, D. J., Townsend, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct,+microwave-assisted+substitution+of+anomeric+nitrate-esters.">Direct, microwave-assisted substitution of anomeric nitrate-esters.</a> Carbohydr. 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Yazarlar hiçbir rakip mali ilgi alanlarına sahip.

Bu öğreticide açıklanan protokol nitrat esterleri yararlı, reaktif işlevselliği için dönüştürmek için bir yöntem sağlar. Daha geniş bir anlamda, karbonhidrat sentezi boyunca belirli manevra tamamlamak için bir mikrodalga reaktör istihdam zor dönüşümleri facile ve rutin hale potansiyeline sahiptir. Amacımız bu eğitimde nasıl karbonhidrat mikrodalga ışınlama bağlamında ele göstermektir.
Üst tepki söz konusu olduğunda, kaslarda elde etmek için önceki çabalar?...

Onların aynı anda her yerde nedeniyle moleküler biyoloji, kimyasal sentez için uzun süredir devam eden hedefler karbonhidrat olmuştur. 1 , 2 , 3 herhangi bir başarılı sentetik kampanya özünde oligosakkarit zinciri glikozilasyon tepkiler doğru dağıtımıdır. 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 beklendiği gibi çok sayıda glycosidic Tahvil yüklemek için yöntem vardır. 13 , 14 Koenigs-Knorr yöntemi en erken bilinen yordamlardan biri ve ağır metal (cıva veya gümüş) etkinleştirme altında genellikle alkollü bir bileşeni ile bir glikosil klorür veya bromür kaplin içerir. 15 ilgili glikosil fluorides bağış Mukaiyama grubu tarafından 1981 yılında ilk kez sunulan ve onların artan termal ve Kimyasal kararlılığı nedeniyle yaygın uygulama bulduk. 16 reaktivite yelpazenin karşıt ucunda diğer halojenürlerden çok daha reaktif glikosil iodides vardır. Artan reaktivite özellikle ne zaman oluşturan α bağlantılı oligosakkaritler artan stereocontrol tarafından eşlik ediyor. 17 ek olarak "haloglycosides", thioglycosides geniş yardımcı programı, kısmen, oluşumu, istikrar reaksiyon koşulları ve harekete geçirmek electrophilic reaktifleri ile çok sayıda kolaylığı nedeniyle bulduk. 18
"Oksijen olmayan" içeren bir için bir anomerik alkol etkinleştirilir ve sonuçta bir alıcısı molekül bir alkol yerlerinden gruptan ayrılma gizli dönüştürme üzerinde odak açıklanan yöntemleri. Anomerik oksijen etkinleştirme Schmidt okul tarafından açıklandığı gibi bırakarak bir gruba C1 oksijen kendisi, dönüştürme üzerinde duruluyor. 19 bu yöntem en güçlü ve yaygın olarak kullanılan kimyasal glikozilasyon reaksiyonlar. Trichloroacetimidate bağış kolayca azalan bakiyeli bir şeker ve trichloroacetonitrile potasyum karbonat (K2CO3) veya 1,8-diazabicyclo [5.4.0] undec-7-Doğu (DBU) gibi bir üs huzurunda hazırlanır. Bu tür sonra Lewis asitleri kullanılarak etkinleştirilir. 20
Son zamanlarda, 2-azido-1-trichloroacetimidate bağış doğrudan glycals hazırlanmış olabilir bildirdin. İşlem iki bir tepki, 2-azido-1-nitrat esterleri bir pot yordam içerir. 21 bu ayrıntılı iletişim kuralı uygulayıcıları yüksek verim dönüştürme başarıyla tamamlamanıza yardımcı olacak tasarlanmıştır. Özel ilgi hangi odak üstünde altında mikrodalga - termal kaslarda Isıtma destekli dizisinin ilk adımdır. Ayrıca görsel bir öğretici mikrodalga reaktörlerde Organik sentez istihdam sağlamak umuyoruz.

<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

One-pot dönüştürme bir 2-azido-1-nitrat-ester trichloroacetimidate glikosil verici bir gösteri sağlamak için aşağıdaki yordamı hedefidir. Bir glycal, azido-nitration, ürün 2-azido-1-nitrat ester mikrodalga destekli ışınlama altında hidrolize. Bu dönüşüm genellikle genişletilmiş tepki süreleri ve güçlü Nükleofilik reaktifler kullanarak elde edilir. Mikrodalga ışınlama hidroliz yokluğunda reaktifler, kısa tepki süreleri ile neden olmaktadır. Kaslarda ara anomerik alkol, karşılık gelen 2-azido-1-trichloroacetimidate için aynı tencerede dönüşür.

Burada açıklanan teknoloji üç 2-azido-1-nitrat esterleri bir havuzu üzerinde gösterilmiştir. Her durumda reaksiyon ilk adım tam 20 dakika içinde.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56610/56610fig2v3.jpg"> Şekil 2. Hidroliz temsilcisi örnek (1 ->2) ve 2-azido-1-nitrat ester 1 one-pot dönüşüm (1->3...

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 mikrodalga destekli dönüşüm anomerik nitrat-esterleri Trichloroacetimidates

Bir 2-azido-1-nitrat-ester karşılık gelen 2-azido-1-trichloroacetimidate bir pot yordamdaki dönüştürülebilir. El yazması karbonhidrat sentezi mikrodalga reaktörde yarar göstermek için hedeftir.

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 ...

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

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7.4K Görüntüleme.  Vanderbilt University. Bir 2-azido-1-nitrat-ester karşılık gelen 2-azido-1-trichloroacetimidate bir pot yordamdaki dönüştürülebilir. El yazması karbonhidrat sentezi mikrodalga reaktörde yarar göstermek için hedeftir.

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.

Intermediate Peroksitlerin yoluyla fotokimyasal ve Asit-katalize CH fonksiyonlandırmalar tarafından Antiviral tetrahidrokarbazole Türevlerinin Sentezi (CİPS)

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 ...

Kimya

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.

İyonik Sıvılar ARACILI 1,6-Ketoester son derece Stereoseçici Sentezi: Düşük Molekül Ağırlıklı Gelators Yeni Bir Sınıf Rapid Erişim etkinleştirilmesi A Üç bileşenli Tepki

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.

Sentezi İçin Protokol<em&gt; Ortho</em&gt; -trifluoromethoxylated Anilin türevleri

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.

Kolay Hazırlık (2<em&gt; Z</em&gt; 4<em&gt; E</em&gt;) - Alil Asetat ile Elektronuz Alkenlerin Olefinasyonu ile Dienamidler

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.

Nhazırlanması-(2-alkoxyvinyl) N- tosyl-1,2,3-triazoles ve yerine Phthalans ve fenitilaminler sonraki dönüşüm sülfonamidler

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.

Fonksiyonel Monoorganozinc Bromides Conjugate Ilavesi ile tüm karbon Dörernary merkezlerinin verimli sentezi

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%.

1-Aryl-1H-pyrazole-5-aminlerin mikrodalga destekli hazırlanması

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.

Trikarbonil(tropon) demir ilerbulu 6-aminosiklohepta-2,4-dien-1-bir Türevlerinin hazırlanması

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.

Çok Yönlü CO2 Karmaşık Ürünlere Dönüşümler: Tek potlu İki Aşamalı Strateji

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.

Geçiş Metal Kataliz Kullanarak Ketonların Mikrodalga Destekli Doğrudan Heteroarylasyon

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

One-pot mikrodalga destekli dönüşüm anomerik nitrat-esterleri Trichloroacetimidates

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