Name: preparation and use of samarium diiodide (smi2) in organic synthesis: the mechanistic role of hmpa and ni(ii) salts in the samarium barbier reaction
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Description: Watch this Scientific Journal Video about Preparation and Use of Samarium Diiodide SmI2 in Organic Synthesis: The Mechanistic Role of HMPA and NiII Salts in the Samarium Barbier Reaction at JoVE.com

RAF bu çalışmaları desteklemek için Ulusal Bilim Vakfı (CHE-0844946) teşekkür eder.

1. SMI 2 sentezi (0.1 M) <ol><li> Alev bir 50 ml&#39;lik yuvarlak dipli balon kurumaya ve argon ile yıkayın. Bir karıştırma çubuğu ekleyin ve septa ile şişesi kapağı. Samaryum metali (0.2 g, 1.3 mmol) tartılır ve tekrar argon ile şişeyi çalkalama, şişeye ilave edin. </li><li> Iyot kristaller (0.254 g, 2.0 mmol), ardından 10 mL kuru, gazı iyice tetrahidrofuran (THF) ilave edilir. Burnun bir argon balon ekleyin; Bu reaksiyon üzerinde Ar atmosferde bir pozitif basınç tutar. </li><li> 3 saat boyunca oda sıcaklığında kuvvetli bir şekilde karıştırarak. SMI 2 üretilir gibi çözüm renk değişiklikleri çeşitli geçer; turuncu sarı (45 dk), ve sonunda mavi dönüşür yeşil (1 saat) izledi. </li><li> Nihai lacivert renk tek başına iyonlaşmış samaryum oluştuğuna göstergesidir. Tam dönüşüm sağlamak amacıyla, sentez SMI 2 kullanılmadan önce en az 3 saat süreyle çözelti karıştırılır. </li></ol> 2. Samarium Barbier Reaksiyon-heksametilfosforamid (HMPA) Toplama <ol><li> SMI 2-HMPA kompleks hale getirmek için, argon altında, taze hazırlanmış SMI 2 (10 ml, 0.1 M, 1.0 mmol) almak ve argon altında bir şırınga, damla damla yoluyla HMPA ve 1.75 ml (10 eşdeğer., 10 mmol) ilave edin. Derin mor renk formları. </li><li> Ayrı bir argon, eklenti iodododecane (0.45 mmol, 110 ul), 3-pentanon (0.45 mmol, 48 ul) ve kuru THF içinde 2 ml altında temiz, kuru bir şişe içinde. </li><li> SMI 2 / HMPA kompleksi damla damla substrat çözeltisi karışımı ekleyin. </li><li> Karıştırarak 5 dakika içinde, mor renk reaksiyon sonunda gösteren, bulanık bakmaya başlar. </li><li> Reaksiyon tamamlandıktan sonra, gidermek için havaya maruz çözelti, sarı renk değişimleri daha fazla karıştırma üzerine. </li><li> Reaksiyon daha sonra doymuş sulu amonyum klorür ile yıkama ile işlenmiş. Bir ayırma hunisine solüsyonu eklenir ve dietil eter (5 mi) ilave edilir. Dinç sallama kaldırdıktan sonraüst organik tabaka, daha fazla dietil eter ekleyin. Sulu tabaka iki kere daha ayıklamak ve daha sonra organik katmanlar, her bir araya getirir. </li><li> Sulu sodyum tiyosülfatın bir doymuş çözeltisi ile organik tabaka yıkayın. Su ve sonra tuzlu su ile yıkama ile son yıkamadan ve ardından alt tabaka sulu, kaldırın. En iyi organik tabaka elde edilir ve çözelti içinde su bulunan herhangi bir son miktarı kadar emmek için magnezyum sülfat ekleyin. </li><li> HMPA fazla çıkarmak için Florisil tıpası içinden çözelti geçirir. </li><li> Barbier ürünü elde etmek için bir döner buharlaştırıcı üzerinde konsantre çözelti. Ürün GCMS ve 1H NMR ile tespit edilmiştir. 23 </li></ol> 3. Samaryum Barbier Reaksiyon-Ni (acac) 2 Katalistli <ol><li> Ni (acac) 2 (1 mol%, 0.01 mmol, 0.0026 g) tartılır ve argon altında gazı alınmış THF içinde 3 ml ihtiva eden bir temiz, kuru bir şişeye eklenir. Taze hazırlanmış ler için bir şırınga aracılığıyla Ni (acac) 2 çözeltisi ekle0.1 M SMI 2 (1.0 mmol, 10 mL) olution. </li><li> Ayrı bir argon, eklenti iodododecane (0.45 mmol, 110 ul), 3-pentanon (0.45 mmol, 48 ul) ve kuru THF içinde 2 ml altında temiz, kuru bir şişe içinde. </li><li> SMI 2 / Ni karışımına damla damla substrat solüsyonu eklenir. </li><li> Karıştırarak on beş dakika içinde, mavi renk reaksiyon sonunda gösteren bir sarı-yeşil renk oluşturmak için dağılacaktır. </li><li> Reaksiyon tamamlandıktan sonra, gidermek için havaya maruz çözelti, sarı renk değişimleri daha fazla karıştırma üzerine. 0.1 M aq ile yıkayarak reaksiyonu çalışın. Hidroklorik asit (3 ml) eklenmiştir. Bir ayırma hunisine solüsyonu eklenir ve dietil eter (5 mi) ilave edilir. </li><li> Sodyum tiyosülfat, su ve tuzlu su, sulu bir çözelti ile birlikte daha önce tarif protokol, ve magnezyum sülfat üzerinde kurutulur kullanarak organik tabaka yıkayın. Barbier ürün elde etmek üzere konsantre çözelti. Ürün GCMS ve 1H NMR ile tespit edilebilir. 28 </skadar&gt; </li></ol>

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Çıkar çatışması ilan etti.

En yaygın katkı maddeleri kullanılarak iki SMI 2 çözeltisi ve organik sentez uygulanışı üretmek için bir basit bir prosedür sunulmuştur. Iki örnek ince ayar SMI 2 reaktivitesi ile reaksiyon mekanik kavrama bölgesinin önemini tasvir tanımlanmıştır. Reaksiyon mekanizmasının temelinin bilinmesi onların reaksiyon ihtiyaçlarına göre sentetik kimyagerler tarafından adapte edilecek bu reaktifin kullanılmasına izin verir. Bu tek elektron homojen indirgeyici kullanımı kolaydır ve ticari kaynaklardan satın alınabilir. Yukarıdaki protokol eylemsiz şartlar altında yapıldığında yalındır iken, ortak sorun giderme yordamları bazıları şunlardır: (a) Sm metal havaya uzun süre maruz Etti (b) bir olabilir, THF düzgün gazı ve kuru olduğundan emin olun dış tabaka okside, temiz bir metal yüzeyini ortaya çıkaracak şekilde bir havan ve pestal ile metal öğütmek (c)Alev kuru argon altında, bütün cam eşya ve serin, (d) daha sonra metal ile etkileşim için gösterildiği gibi argon, azot fazla inert atmosfer tercih edilir (e) SM metal fazlalığının varlığı SMI konsantrasyonunu korumaya yardımcı olur iyot kristali 2, (f) resublime.

<table border="1"><tbody><tr><td> Reaktif Adı </td><td> Şirket </td><td> Katalog numarası </td><td> Yorumlar (isteğe bağlı) </td></tr><tr><td> Samaryum metal </td><td> Acros </td><td> 29478-0100 </td><td> -40 Mesh,% 99.9 (metaller bazında) </td></tr><tr><td> THF </td><td> OmniSolv </td><td> TX0282-1 </td><td> Yenilikçi Teknolojiler solvent arıtma sistemi ile saflaştırılmış. Alternatif olarak ücretsiz-pompa-çözülme yöntemi ile giderildi edilebilir </td></tr><tr><td> Iyot </td><td> Alfa Aesar </td><td> 41955-22 </td><td> Resublimed kristaller,% 99.8 </td></tr><tr><td> Iodododecane </td><td> Acros </td><td> 25009-0250 </td><td> % 98 </td></tr><tr><td> 3-pentanon </td><td> Alfa Aesar </td><td> AAA15297-AE </td><td> % 99 </td></tr><tr><td> HMPA </td><td> Alderich </td><td> H11602 </td><td> % 98; Argon altında CaO dan damıtmak </td></tr><tr><td> Nii 2 </td><td> Alfa Aesar </td><td> 22893 </td><td> % 99.5 (metaller bazında) </td></tr></tbody></table>

preparation and use of samarium diiodide (smi2) in organic synthesis: the mechanistic role of hmpa and ni(ii) salts in the samarium barbier reaction

Başlangıçta ezoterik bir reaktif kabul olsa da, SMI 2 sentetik organik kimyacılar için ortak bir araç haline gelmiştir. SMI 2 THF içinde samaryum metal moleküler iyot eklenmesiyle oluşturulur. 1,2-3 bir hafif ve seçici bir elektron redükleyici ve çok yönlülüğü CC azaltılması dahil olmak üzere, geniş bir yelpazede başlatmak kabiliyetini bir sonucudur-bağ şekillendirme ve kaskad veya ardışık reaksiyonlar. SMI 2 sülfoksitler ve sülfonlar, fosfin oksitler, epoksitler, alkil ve aril halojenürler, karbonil, ve konjüge çift bağ da dahil olmak üzere fonksiyonel grupların çeşitli azaltabilir. SMI-2-aracılı reaksiyon ilginç özelliklerinden biri, 2-12 yeteneği solvent veya katkı seçici kullanımı yoluyla reaksiyon sonucu işleyebilirsiniz. Çoğu durumlarda, katkı maddeleri redüksiyon oranı ile kemo-ya da stereoselektivite reaksiyonların kontrol edilmesinde çok önemlidir. 13-14 Katkı commonly SMI 2 reaktivitesi üç ana gruba ayrılabilir hassas bir şekilde ayarlamak için kullanılmaktadır: (1) Lewis bazları (HMPA, diğer elektron-verici ligandlar, çelatlama eterler gibi), (2) proton kaynağı (alkoller, su, vs ), ve (3) inorganik katkı maddeleri (Ni (acac) 2, FeCl 3, vs.) 3. SMI 2 reaksiyon mekanizması ve katkı maddelerinin rolünü anlamak organik sentez içinde reaktif bir tam potansiyel kullanımı sağlanmaktadır. Bu reaksiyon için HMPA ve Ni (II): Sm-Barbier reaksiyon sentetik önem ve iki ortak katkı maddelerinin mekanik bir rol göstermek için seçilmiştir. Sm-Barbier reaksiyon alkil halid, karbonil, Sm ve indirgeyici bir kap içinde aynı anda karıştırılır olan tek fark ile geleneksel Grignard reaksiyonu ile benzerdir. Bağlama ortağı arasında bir dizi ile Sm-aracılı Barbier reaksiyon 1,15 Örnekleri bildirilmiştir, 1,3,7,10,12 ve ut olmuşturbüyük doğal ürünlerin sentezi anahtar adım ilized. SMI 2 reaksiyon katkı maddelerin etkisi ile ilgili daha önceki çalışmalarda 16,17 HMPA daha güçlü bir üreten, samaryum metal koordinasyon merkezine göre SMI 2 indirgeme potansiyelini arttırır göstermiştir ki, 13-14,18 sterik indirgeyici 19-21 ipotekli ve Sm-Barbier sonraki reaksiyonda bağ-oluşturucu etkinlikler kolaylaştıran sonrası elektron transfer adımda bir tamamlayıcı bir rol oynar. 22 oynama bazı durumlarda, HMPA ayrıca alkil halid aktif hale getirmek için gösterilmiştir bir ön denge adımda bir kompleks oluşturarak. 23 Ni (II) tuzları, Sm-aracılı dönüşüm sıklıkla kullanılan bir katalizör eklenebilir. Başarısı için kritik olmasına rağmen 24-27, Ni (II) &#39;nin mekanistik rol bu tepkimeler de bilinmemektedir. Yakın zamanda, SMI 2 Ni (0) Ni (II) azalttığı gösterilmiştir, ve reaksiyon daha sonra organome yoluyla gerçekleştirilirtallic Ni (0) kimyası. 28. Bunlar, mekanik çalışmalar, aynı Barbier ürün elde edilmiş olmasına rağmen, SMI 2 reaksiyonu içinde farklı katkı maddelerinin kullanımı ile büyük ölçüde reaksiyon mekanistik yolu değiştirir olduğu görülmüştür. Bu SMI çalıştırmak için protokol 2-tepkimesi tarif edilmektedir.

Şekil 1, samaryum Barbier reaksiyon göstermektedir. Herhangi bir katkı maddesi ile birlikte Sm-aracılı reaksiyon 72 saat sürer; kalan kısmında ise başlangıç ​​maddeleri ile istenen ürün% 69 elde edilmiştir. 10 veya daha fazla eşi ilavesi ile. HMPA ve reaksiyon birkaç dakika içinde hemen hemen nicel ve tamam olmaktadır. 1 mol% Ni (acac) 2 eklenmesi ile 15,23, reaksiyon bir% 97 verim ile, 15 dakika içinde tamamlandı. 28 (HMPA) 4 - HMPA SMI 2, yardımcı solvent yerinden SMI 2 oluşturacak şekilde koordine THF eklenir. Hatta daha fazla HMPA (6-10 eşi.) Ilavesi ile, iyodür iyonu dış alan (Şekil 2) ile deplase olur. 19-21 mekanik çalışmalar HMPA Sm-Barbier tepki olarak kullanıldığı zaman da yardımcı solvent etkileşim göstermek alkil halojenür yüzey s aktive karbon-halide bağı uzatır karmaşık bir şekillendirme ilepecies Sm tarafından azaltma (Şekil 3) daha hassas hale getirir. HMPA, HMPA ile Sm-Barbier reaksiyon mekanizmasının Bu rollerin detaylı anlayış sayesinde (Şekil 4) önerilmiştir. 23 öncesi bir denge adımda oluşan alkil halojenür-HMPA kompleksi Sm / HMPA azalır oluşturmak için Adım tespit oranı radikaldir. Radikal karbonil ve protonasyon üzerinde çiftler nihai ürün verimleri organosamarium bir tür oluşturmak üzere daha da azaltılması uğrar. Ni (II) katkı maddesi söz konusu olduğunda, SMI 2 başlangıçta tercihen alt tabaka ya da azaltılması üzerinde Ni (0) Ni (II) azaltır. Kinetik ve mekanik çalışmalar sonucu aşağıdaki mekanizma (Şekil 5) öngörülmüştür. Bir organonikel türlerinin oluşumuna alkil halid bağ içine 28 SMI 2 tarafından düşürülmesinden sonra, çözünür Ni (0) tür ekler. Sm çok oxophilic doğası (III) ile tahrik<html> Geri katalitik döngü içine bir organosamarium ara bültenleri Ni (II) oluşturmak üzere transmetalasyon. Daha sonra organosamarium karbonil çiftler, ve protonasyon üzerine arzu edilen üçüncül alkol oluşturur. Aynı zamanda, Ni (0) nanopartiküllerin Ni Sm-aracılı azalma (II) ile oluşur olduğu görülmüştür, ancak bu parçacıklar atıl ve katalizör deaktivasyon kaynak olduğu bulunmuştur. <img alt="Şekil 1" fo:content-width="4in" fo:src="/files/ftp_upload/4323/4323fig1highres.jpg" src="/files/ftp_upload/4323/4323fig1.jpg" /> Iodododecane ve 3-pentanon ile, Şekil 1. Samaryum Barbier reaksiyon. <img alt="Şekil 2," fo:content-width="4in" fo:src="/files/ftp_upload/4323/4323fig2highres.jpg" src="/files/ftp_upload/4323/4323fig2.jpg" /> Şekil 2. SMI 2-HMPA kompleksi. ontent &quot;fo: keep-together.within-page =&quot; always &quot;&gt; <img alt="Şekil 3" fo:content-width="3.5in" fo:src="/files/ftp_upload/4323/4323fig3highres.jpg" src="/files/ftp_upload/4323/4323fig3.jpg" /> Şekil 3,. HMPA ve alkil iyodür kompleksi. <img alt="Şekil 4," fo:content-width="4.5in" fo:src="/files/ftp_upload/4323/4323fig4highres.jpg" src="/files/ftp_upload/4323/4323fig4.jpg" /> Şekil 4. Aşırı HMPA ile samaryum Barbier reaksiyon için önerilen mekanizma. <img alt="Şekil 5," fo:content-width="4in" fo:src="/files/ftp_upload/4323/4323fig5highres.jpg" src="/files/ftp_upload/4323/4323fig5.jpg" /> Şekil 5,. Katalitik Ni (II) içeren samaryum Barbier reaksiyon için önerilen mekanizması.

Watch this Scientific Journal Video about Preparation and Use of Samarium Diiodide SmI2 in Organic Synthesis: The Mechanistic Role of HMPA and NiII Salts in the Samarium Barbier Reaction at JoVE.com

Preparation and Use of Samarium Diiodide SmI2 in Organic Synthesis: The Mechanistic Role of HMPA and NiII Salts in the Samarium Barbier Reaction

Samaryum diiodide hazırlanması için bir basit bir prosedür (SMI<sub&gt; 2</sub&gt;) THF içinde tarif edilmektedir. (Acac) yani heksametilfosforamid (HMPA) ve Ni iki ana katkı maddeleri rol<sub&gt; 2</sub&gt; Sm aracılı reaksiyonlar Sm-Barbier tepki gösterilmiştir.

Hazırlanması ve Samaryum Diiodide Kullanımı (SMI<sub&gt; 2</sub&gt;) In Organic Synthesis: Samaryum Barbier Reaksiyonu HMPA ve Ni (II) tuzlarının Mekanistik Rolü

Although initially considered an esoteric reagent, SmI2 has become a common tool for synthetic organic chemists. SmI2 is generated through the addition of ...

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Universidad de Cartagena UDEC

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JoVE Journal

Chemistry

Preparation and Use of Samarium Diiodide (SmI2) in Organic Synthesis: The Mechanistic Role of HMPA and Ni(II) Salts in the Samarium Barbier Reaction

32.8K Görüntüleme.  Lehigh University. Samaryum diiodide hazırlanması için bir basit bir prosedür (SMI 2) THF içinde tarif edilmektedir. (Acac) yani heksametilfosforamid (HMPA) ve Ni iki ana katkı maddeleri rol 2 Sm aracılı reaksiyonlar Sm-Barbier tepki gösterilmiştir.

Video: Preparation and Use of Samarium Diiodide SmI2 in Organic Synthesis: The Mechanistic Role of HMPA and NiII Salts in the Samarium Barbier Reaction

Synthesis and Purification of Iodoaziridines Involving Quantitative Selection of the Optimal Stationary Phase for Chromatography

The highly diastereoselective preparation of cis-N-Ts-iodoaziridines through reaction of diiodomethyllithium with N-Ts aldimines is described. Diiodomethyllithium is prepared by the deprotonation of diiodomethane with LiHMDS, in a THF/diethyl ether mixture, at -78 &#176;C in the dark. These conditions are essential for the stability of the LiCHI2 reagent generated. The subsequent dropwise addition of N-Ts aldimines to the preformed diiodomethyllithium solution affords an amino-diiodide intermediate, which is not isolated. Rapid warming of the reaction mixture to 0 &#176;C promotes cyclization to afford iodoaziridines with exclusive cis-diastereoselectivity. The addition and cyclization stages of the reaction are mediated in one reaction flask by careful temperature control.
Due to the sensitivity of the iodoaziridines to purification, assessment of suitable methods of purification is required. A protocol to assess the stability of sensitive compounds to stationary phases for column chromatography is described. This method is suitable to apply to new iodoaziridines, or other potentially sensitive novel compounds. Consequently this method may find application in range of synthetic projects. The procedure involves firstly the assessment of the reaction yield, prior to purification, by 1H NMR spectroscopy with comparison to an internal standard. Portions of impure product mixture are then exposed to slurries of various stationary phases appropriate for chromatography, in a solvent system suitable as the eluent in flash chromatography. After stirring for 30 min to mimic chromatography, followed by filtering, the samples are analyzed by 1H NMR spectroscopy. Calculated yields for each stationary phase are then compared to that initially obtained from the crude reaction mixture. The results obtained provide a quantitative assessment of the stability of the compound to the different stationary phases; hence the optimal can be selected. The choice of basic alumina, modified to activity IV, as a suitable stationary phase has allowed isolation of certain iodoaziridines in excellent yield and purity.

A protocol for the diastereoselective one-pot preparation of cis-N-Ts-iodoaziridines is described. The generation of diiodomethyllithium, addition to N-Ts aldimines and cyclization of the amino gem-diiodide intermediate to iodoaziridines is demonstrated. Also included is a protocol to rapidly and quantitatively assess the most appropriate stationary phase for purification by chromatography.

Sentez ve Kromatografi için optimal sabit faz kantitatif seçimi dahil edilmesi Iodoaziridines saflaştırılması

The highly diastereoselective preparation of cis-N-Ts-iodoaziridines through reaction of diiodomethyllithium with N-Ts aldimines is described. ...

Kimya

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel &#945;-diimine ethylene polymerization catalyst. Initial polymerizations with the catalyst lead to optimized reaction conditions, including catalyst concentration, ethylene pressure and reaction time. Using gas-uptake data for these reactions, a procedure to calculate the initial rate of propagation (kp) is presented. Using the optimized conditions, the ability of the nickel &#945;-diimine polymerization catalyst to undergo chain transfer with diethylzinc (ZnEt2) during ethylene polymerization was investigated. A procedure to assess the ability of the catalyst to undergo chain transfer (from molecular weight and 13C NMR data), calculate the degree of chain transfer, and calculate chain transfer rates (ke) is presented.

A protocol for the high-throughput analysis of polymerization catalyst, chain transfer polymerizations, polyethylene characterization, and reaction kinetic analysis is presented.

Paralel Basınç Reaktörleri ve Zincir Transferi Polimerizasyon bir Kinetik Analizi Etilen Polimerizasyonlar

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel ...

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. Detailed and generalized protocols are also presented for testing the catalytic activity of such complexes in arylation and Suzuki-Miyaura cross-coupling reactions. Representative results are shown for the catalytic activity of the four complexes in arylation and Suzuki-Miyaura type reactions. For each of the reactions investigated, at least one of the four complexes successfully catalyzed the reaction, qualifying them as promising candidates for catalysis of many carbon-carbon bond-forming reactions. The protocols presented are general enough to be adapted for the synthesis, purification and catalytic activity testing of new palladium N-heterocyclic carbene complexes.

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. The complexes were tested for catalytic activity in arylation and Suzuki-Miyaura reactions. For each reaction investigated, at least one of the four complexes successfully catalyzed the reaction.

palladyum<em&gt; K</em&gt; -Heterosiklik Karben Kompleksleri: Benzimidazolyum Tuzlarından Sentez ve Karbon-karbon Bağ Oluşturma Reaksiyonlarında Katalitik Aktivite

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from ...

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable low-valent-phosphorus-containing compound acts as a useful P+ transfer agent. Unlike traditional methods employed to access low-coordinate phosphorus species which usually require pyrophoric phosphorus-containing precursors (white phosphorus, Tris(trimethylsilyl)phosphine, etc.), or harsh reducing agents (alkali metals, potassium graphite, etc.), the current approach does not involve pyrophoric or explosive reagents and can be done on large scales (&#62;20 g) in excellent yields by undergraduates with basic air-free synthetic training. The bromide counter ion is readily exchanged with other anions such as tetraphenyl borate (described herein) using typical salt metathesis reagents to obtain materials with desired properties and reactivities. The versatility of this P+ transfer approach is exemplified by the reactions of these triphosphenium precursors with an N-heterocyclic carbene and an anionic bisphosphine, each of which readily displace the neutral bisphosphine to give an NHC-stabilized phosphorus(I) cation and a phosphorus(I) containing zwitterion, respectively.

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI

The synthesis of a triphosphenium bromide salt is described and its use as a P+ transfer agent is outlined by reactions with an N-heterocyclic carbene and an anionic bisphosphine, yielding an NHC-stabilized P(I) cation and a P(I) containing zwitterion, respectively.

Bir Triphosphenium Bromür Tuz Hazırlanması ve Tepkime: Fosfor A Rahat ve kararlı Kaynak (I)

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable ...

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants

We present the synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high purity nonsymmetric dialkylphosphinic acid extractants. Low toxic sodium hypophosphite was chosen as the phosphorus source to react with olefin A (2,3-dimethyl-1-butene) to generate a monoalkylphosphinic acid intermediate. Amantadine was adopted to remove the dialkylphosphinic acid byproduct, as only the monoalkylphosphinic acid can react with amantadine to form an amantadine&#8729;mono-alkylphosphinic acid salt, while the dialkylphosphinic acid cannot react with amantadine due to its large steric hindrance. The purified monoalkylphosphinic acid was then reacted with olefin B (diisobutylene) to yield nonsymmetric dialkylphosphinic acid (NSDAPA). The unreacted monoalkylphosphinic acid can be easily removed by a simple base-acid post-treatment and other organic impurities can be separated out through the precipitation of the cobalt salt. The structure of the (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid was confirmed by 31P NMR, 1H NMR, ESI-MS, and FT-IR. The purity was determined by a potentiometric titration method, and the results indicate that the purity can exceed 96%.

A protocol for the synthesis of high purity nonsymmetric dialkylphosphinic acid extractants is presented, taking (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example.

Yüksek saflıkta Nonsymmetric Dialkylphosphinic asit Extractants sentezi

We present the synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high ...

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, allowing for the synthesis of isotactic poly(&#945;-hydroxy acids) with expected molecular weights (&#62;140 kDa) and narrow molecular weight distributions (Mw/Mn &#60; 1.1). This ring-opening polymerization is mediated by Ni and Zn complexes in the presence of an alcohol initiator and a photoredox Ir catalyst, irradiated by a blue LED (400 - 500 nm). The polymerization is performed at a low temperature (-15 &#176;C) to avoid undesired side reactions. The complete monomer consumption can be achieved within 4 - 8 hours, providing a polymer close to the expected molecular weight with narrow molecular weight distribution. The resulted number-average molecular weight shows a linear correlation with the degree of polymerization up to 1000. The homodecoupling 1H NMR study confirms that the obtained polymer is isotactic without epimerization. This polymerization reported herein offers a strategy for achieving rapid, controlled O-carboxyanhydrides polymerization to prepare stereoregular poly(&#945;-hydroxy acids) and its copolymers bearing various functional side-chain groups.

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

A protocol for the controlled photoredox ring-opening polymerization of O-carboxyanhydrides mediated by Ni/Zn complexes is presented.

Photoredox yüzük-açılış polimerizasyon O- Carboxyanhydrides Ni/Zn kompleksleri tarafından aracılı ile kontrol

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

We present the chemoselective synthesis of 1-(iodoethynyl)-4-methylbenzene, 1-(1,2-diiodovinyl)-4-methylbenzene, and 1-methyl-4-(1,2,2-triiodovinyl)benzene as representative examples for the practical chemoselective preparation of 1-iodoalkynes, 1,2-diiodoalkenes, and 1,1,2-triiodoalkenes from the chemoselective iodination of terminal alkynes mediated by hypervalent-iodine reagents. The chemoselectivity was confirmed by using p-tolylethyne as a model substrate to screen a variety of iodine sources and/or the hypervalent-iodine reagents. A combination of tetrabutylammonium iodide (TBAI) and (diacetoxyiodo)benzene (PIDA) selectively generates 1-iodoalkynes, while a combination of KI and PIDA generates 1,2-diiodoalkenes. A one-pot synthesis based on both TBAI-PIDA and KI-PIDA yields the corresponding 1,1,2-triiodoalkenes. These protocols were subsequently applied to the synthesis of synthetically important aromatic and aliphatic 1-iodoalkynes, 1,2-diiodoalkenes, and 1,1,2-triiodoalkenes, which were obtained in good yield with excellent chemoselectivity.

Herein, detailed protocols for the oxidative iodination of terminal alkynes using hypervalent-iodine reagents are presented, which chemoselectively afford 1-iodoalkynes, 1,2-diiodoalkenes, and 1,1,2-triiodoalkenes.

1-Iodoalkynes, 1,2-Diiodoalkenes ve 1,1,2-Triiodoalkenes Terminal Alkynes oksidatif iyodinasyon üzerinde dayalı Chemoselective hazırlanması

We present the chemoselective synthesis of 1-(iodoethynyl)-4-methylbenzene, 1-(1,2-diiodovinyl)-4-methylbenzene, and ...

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, &#60;10-5 mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 &#176;C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. 1H and 13C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei (15N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol&#183;g-1) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [(&#8801;Si-O-)Hf(&#951;2&#960;-MeNCH2)(&#951;1-NMe2)(&#951;1-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)]. [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is correlated to the catalytic performance.

A new group IV metal catalyst for imine metathesis is prepared by grafting amine metal complex onto dehydroxylated silica. Surface metal fragments are characterized using FT-IR, elemental microanalysis, and solid-state NMR spectroscopy. Further dynamic nuclear polarization surface enhanced NMR spectroscopy experiments complement the determination of the coordination sphere.

Yüzey Organometalik Kimya metodolojisini kullanan Silika Destekli Katalizörler tarafından Imine Metatez

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared ...

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 ...

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 ...

Hazırlanması ve Samaryum Diiodide Kullanımı (SMI

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