目前的工作得到了 BUAP、推广科学和项目编号 Vicerrectoría de Investigación y 研究中心 Posgrado 的支持。REOY-NAT14, 15, 16 克 HEAS-NAT17。RMG 感谢 CONACyT (墨西哥) 奖学金417887。

1. 反应
<ol><li>在通风罩中放置一个打开的圆形100毫升瓶与0.5 摩尔 (29.8 毫升) 的冰川醋酸和添加0.051 摩尔 (5.82 毫升) 35-吡啶和5毫升的 H2O2 (35%)。保持混合反应在恒定的磁性搅拌下, 在内部温度为80°c 为5小时。</li>
	<li>在反应时间以后, 冷却烧瓶到24°c 与冰 (不暴露乙酸气体到冰), 并且插入它到一个高真空蒸馏单位为90-120 分钟去除多余的乙酸。 注意: 不要使用热材料。等待, 直到玻璃器皿达到可控温度。这也将避免蒸汽进入蒸馏装置的顶部。</li>
	<li>添加蒸馏水 (10 毫升) 两次, 以确保去除任何醋酸的痕迹, 并尽可能集中的混合物。</li>
</ol>2. 碱度调整和提取
<ol><li>溶解在双馏分水隔离的粘性和透明的产品, 并使用电位器调整 pH 值为 10, 纯固态 Na2CO3。</li>
	<li>小心地放置在一个250毫升分离漏斗的解决方案, 并提取它5倍250毫升的 CHCl3 , 以提高产量。恢复有机层并将其干燥到固态 Na2, 因此4的最大值为30分钟, 其中将包含产品。如有必要, 请用所需量的 CHCl3重新提取水相。 警告: CHCl3可能导致嗜睡和头晕;小心处理, 并在通风罩内。</li>
	<li>用高真空蒸馏装置去除减压液中的溶剂, 直至形成一种非常吸湿的透明米色结晶粉末 (70%)。</li>
</ol>3. 结晶过程
<ol><li>在50毫升的冷高液相色谱 (HPLC) 二乙基醚中溶解4.3 克的结晶粉末。真空过滤器的解决方案, 以消除任何痕迹的固体起动材料甚至灰尘。将滤液倒入玻璃培养皿中, 使其在实验室冰箱中缓慢蒸发4摄氏度。</li>
	<li>确保两天后, 透明无色晶体得到。然后测量熔点, 它应该在 310-311 K 的范围内。</li>
</ol>4. 35-吡啶n-氧化物脱水的分析
<ol><li>通过迁从烧瓶的墙壁中取出形成的、呈棱镜形状和无色的晶体, 进一步进行 X 射线分析。如果不立即使用, 保持晶体在乙醚, 以避免晶体水化。</li>
	<li>在0.4 毫升 CDCl3中溶解0.010 克的 35-吡啶n-氧化物脱水, 执行核磁共振 H1和 C13分析以证明该过程的有效性。</li>
</ol>

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所有作者声明没有利益冲突。

本文提出的协议是将氧原子与 35-吡啶的氮原子相连接的传统方法, 作为基质的功能化方法。这项技术也很好的建立, 以产生 x 射线合适的脱水晶体 (图 5, 拍摄的照片与一个 DSC-HX300 的网络拍摄索尼相机)。就我们而言, 没有多少报告描述了这种晶体的生产16。许多化合物生长理想晶体的 x 射线分析时, 它们是螯合的各种金属17,18</sup...

如今, 全球各地的科学家一直在为芳香族的功能化开发新的合成路线, 这是众所周知的低反应性前添加反应1,2, 3。吡啶, 其中氮原子替代碳原子, 呈现类似的化学反应的模拟环只组成碳原子3, 它通常会经历替代机制, 而不是加法。N-氧化物由在氧原子3上的 nonbonding 电子对的重叠所形成的氮与氧之间存在的供体键的存在而独特。特别地, 吡啶n-氧化物是刘易斯基地, 因为他们的 n-O 基团可能充当电子捐赠者, 并且他们可能结合刘易斯酸形成对应的刘易斯酸基对。这个物产有一个基本的化学后果, 因为它可能增加路易斯酸的 nucleophilicity 对潜在的 electrophiles, 因此允许他们在通常反应不会发生的情况下反应。可能最频繁使用这种化合物是在各种氧化反应, 它们作为氧化剂4。吡啶N-氧化物和它们的许多环功能性衍生物是生物活性和药理作用的经常性分子5, 并建立了一个清晰的空间分布由不同的光谱工具对于其中一些6,7。在研究将不同的基团附着在吡啶环上时, 科学家们测试了各种方法, 以产生一种简单而传统的方法, 因为 isoxazolines 需要催化量的基础, 如 DBU 在沸腾二甲苯形成 6-substituted-2-aminopyridine N-氧化物8,9。在 CH2Cl2/CH3中, 多种吡啶衍生物转化为相应的N-氧化物, 其催化量为四 (26-diclorophenyl) 卟啉和醋酸铵。CN8,10。其他吡啶被氧化到他们的氧化物使用 H2O2在有催化量的 methyltrioxorhenium8,11, 或由加法多余的 dimethyldioxirane 在 CH2Cl2摄氏0摄氏度, 导致相应的N氧化物8,12,13,14。双 (三甲基硅) 过氧化物在 trioxorhenium 的存在中, 在 CH2Cl2中, 已用于合成吡啶N-氧化物8,11。此外, 还报告了用卡萝酸 (peroxomonosulfuric 酸) 合成氨基吡啶N氧化物的情况8。然而, 这里报告的方法, 以及使用落合1报告的方法的一部分, 提供了非常好的结果, 使用更便宜和容易接近的试剂, H 2 O 2 和冰川乙酸.这种做法更适合用于大型制剂, 对叔胺, 它产生良好的产量, 在一个反应, 只需要30% 过氧化氢和冰川乙酸在70-80 摄氏度之间的温度, 并使用净化过程这是可利用的在多数综合实验室例如蒸馏, 不用催化剂或更昂贵的试剂1。文献报道, 其他方法也经常涉及时间框架从10-24 小时和温度在100°c 4,8, 并且清楚地被形成的水晶的屈服为 x 射线分析很少报告。
被动, 各种n-氧化物衍生物用于充分激活吡啶环, 无论是亲核或亲方式。亲核或亲因子受取代基的影响。随着吡啶环为电子提取基团, 主要因子为亲核特征1。自由的N氧化物化合物很少被隔绝作为适当的水晶为 x-射线分析由于移位充电在芳香圆环。然而, 溶剂化因子对于稳定氧的负密度15至关重要。

<table><tbody><tr><td>3,5-lutidine</td><td>Sigma-Aldrich</td><td>L4206-500ML</td><td></td></tr><tr><td>Glacial acetic acid</td><td>Fermont</td><td>3015</td><td></td></tr><tr><td>Hidrogen peroxide (35%)</td><td>Sigma-Aldrich</td><td>349887-500ML</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;CO&lt;sub&gt;3&lt;/sub&gt; anhydrous</td><td>Productos Qu&amp;iacute;micos Monterrey</td><td>1792</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; anhydrous</td><td>Alfa reactivos</td><td>25051-C</td><td></td></tr><tr><td>CHCl&lt;sub&gt;3&lt;/sub&gt;</td><td>Fermont</td><td>6205</td><td></td></tr><tr><td>Ethyl eter</td><td>Mercury Chemist</td><td>QME0309</td><td></td></tr><tr><td>Distilled water</td><td>Comercializadora Qu&amp;iacute;mica Poblana</td><td>not-existent</td><td></td></tr></tbody></table>

syntheses, crystallization, and spectroscopic characterization of 3,5-lutidine n-oxide dehydrate

合成 35-吡啶n-氧化物脱水, 1, 在 2-氨基吡啶-35 二羧酸的合成路线中实现。落合首次在12小时的过程中使用了非取代吡啶的方法, 但没有获得 X 射线合适的晶体。此处介绍的方法中使用的取代环清楚地影响了将水分子加入不对称单元, 在1中赋予不同的亲核强度。X 射线适当的水晶复合物1是可能的由于消极充电的安定在氧气由二个水分子的存在, 在那里氢原子捐赠正电荷入圆环;这种水分子能很好地构建超分子相互作用。水合分子可能为碱性系统, 通过调整 pH 值达到10。重要的是, 双甲基取代环和反应时间为5小时, 使其成为一个更通用的方法和更广泛的化学应用, 未来的环插入。

该协议实质上是落合技术1的扩展.但是, 较低的温度和更少的时间被应用。这个简单的方法可以用来获得一个多才多艺的配体, 这是一个替代的吡啶N氧化物衍生物。要确认1的形成, 请选择核磁共振1H 和13C 分析, 以测试过程的有效性。
化学位移表明了1的形成。信?...

Watch this Scientific Journal Video about Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate at JoVE.com

Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate

在此, 我们报告的合成和结晶的 35-吡啶n-氧化物脱水的一个简单的协议, 不同于经典合成吡啶N氧化物。该协议采用不同的起始材料, 反应时间较少, 产生一种新的溶解超分子结构, 在缓慢蒸发下结晶。

35-吡啶N-氧化物脱水的合成、结晶和光谱表征

The synthesis of 3,5-lutidine N-oxide dehydrate, 1, was achieved in the synthesis route of 2-amino-pyridine-3,5-dicarboxylic acid. Ochiai first used the ...

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Chemistry

Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate

8.3K 次观看.  Benemérita Universidad Autónoma de Puebla. 在此, 我们报告的合成和结晶的 35-吡啶n-氧化物脱水的一个简单的协议, 不同于经典合成吡啶N氧化物。该协议采用不同的起始材料, 反应时间较少, 产生一种新的溶解超分子结构, 在缓慢蒸发下结晶。

视频: Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate

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.

通过中级过氧化物的抗病毒四氢咔唑衍生物的合成光化学和酸催化CH官能（筹）

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 ...

科研

化学

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

功能化的合成与表征金属 - 有机骨架

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Synthesis of Indoxyl-glycosides for Detection of Glycosidase Activities

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are rapidly oxidized, for example by atmospheric oxygen, to indigo type dyes. This reaction enables fast and easy screening in vivo without isolation or purification of enzymes, as well as rapid tests on agar plates or in solution (e.g., blue-white screening, micro-wells) and is used in biochemistry, histochemistry, bacteriology and molecular biology. Unfortunately the synthesis of such substrates proved to be difficult, due to various side reactions and the low reactivity of the indoxyl hydroxyl function. Especially for glucose type structures low yields were observed. Our novel approach employs indoxylic acid ester as key intermediates. Indoxylic acid esters with varied substitution patterns were prepared on scalable pathways. Phase transfer glycosylations with those acceptors and peracetylated glycosyl halides can be performed under common conditions in high yields. Ester cleavage and subsequent mild silver mediated glycosylation yields the peracetylated indoxyl glycosides in high yields. Finally deprotection is performed according to Zempl&#233;n.

Indoxyl glycosides are well-established and widely used tools for enzyme screening and enzyme activity monitoring. Especially for glucose type structures previous syntheses proved to be challenging and low yielding. Our novel approach employs indoxylic acid esters as precious intermediates to yield a considerable number of indoxyl glycosides in good yields.

的吲哚酚苷的检测糖苷酶活动的合成

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are ...

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the hydroxylmethylene phosphine precursor with ammonia in methanol under a nitrogen atmosphere. The N-triphosPh ligand precipitates from the solution after approximately 1 hr of reflux and can be isolated analytically pure via simple cannula filtration procedure under nitrogen. Reaction of the N-triphosPh ligand with [Ru3(CO)12] under reflux affords a deep red solution that show evolution of CO gas on ligand complexation. Orange crystals of the complex [Ru(CO)2{N(CH2PPh2)3}-&#954;3P] (2) were isolated on cooling to RT. The 31P{1H} NMR spectrum showed a characteristic single peak at lower frequency compared to the free ligand. Reaction of a toluene solution of complex 2 with oxygen resulted in the instantaneous precipitation of the carbonate complex [Ru(CO3)(CO){N(CH2PPh2)3}-&#954;3P] (3) as an air stable orange solid. Subsequent hydrogenation of 3 under 15 bar of hydrogen in a high-pressure reactor gave the dihydride complex [RuH2(CO){N(CH2PPh2)3}-&#954;3P] (4), which was fully characterized by X-ray crystallography and NMR spectroscopy. Complexes 3 and 4 are potentially useful catalyst precursors for a range of hydrogenation reactions, including biomass-derived products such as levulinic acid (LA). Complex 4 was found to cleanly react with LA in the presence of the proton source additive NH4PF6 to give [Ru(CO){N(CH2PPh2)3}-&#954;3P{CH3CO(CH2)2CO2H}-&#954;2O](PF6) (6).

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Ruthenium phosphine complexes are widely used for homogeneous catalytic reactions such as hydrogenations. The synthesis of a series of novel tridentate ruthenium complexes bearing the N-triphos ligand N(CH2PPh2)3 is reported. Additionally, the stoichiometric reaction of a dihydride Ru&#8211;N-triphos complex with levulinic acid is described.

一系列钌的合成，表征和反应<em&gt;Ñ</em&gt; -triphos<sup&gt;博士</sup&gt;配合

Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the ...

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

Organolithium reagents are powerful tools in the synthetic chemist&#39;s toolbox. However, the extreme pyrophoric nature of the most reactive reagents warrants proper technique, thorough training, and proper personal protective equipment. To aid in the training of researchers using organolithium reagents, a thorough, step-by-step protocol for the safe and effective use of tert-butyllithium on an inert gas line or within a glovebox is described. As a model reaction, preparation of lithium tert-butyl amide by the reaction of tert-butyl amine with one equivalent of tert-butyl lithium is presented.

The safe and proper use of organolithium reagents is described.

使用有机锂试剂的一个协议安全的锂化反应

Organolithium reagents are powerful tools in the synthetic chemist&#39;s toolbox. However, the extreme pyrophoric nature of the most reactive reagents ...

Enzymatic Cascade Reactions for the Synthesis of Chiral Amino Alcohols from L-lysine

Amino alcohols are versatile compounds with a wide range of applications. For instance, they have been used as chiral scaffolds in organic synthesis. Their synthesis by conventional organic chemistry often requires tedious multi-step synthesis processes, with difficult control of the stereochemical outcome. We present a protocol to enzymatically synthetize amino alcohols starting from the readily available L-lysine in 48 h. This protocol combines two chemical reactions that are very difficult to conduct by conventional organic synthesis. In the first step, the regio- and diastereoselective oxidation of an unactivated C-H bond of the lysine side-chain is catalyzed by a dioxygenase; a second regio- and diastereoselective oxidation catalyzed by a regiodivergent dioxygenase can lead to the formation of the 1,2-diols. In the last step, the carboxylic group of the alpha amino acid is cleaved by a pyridoxal-phosphate (PLP) decarboxylase (DC). This decarboxylative step only affects the alpha carbon of the amino acid, retaining the hydroxy-substituted stereogenic center in a beta/gamma position. The resulting amino alcohols are therefore optically enriched. The protocol was successfully applied to the semipreparative-scale synthesis of four amino alcohols. Monitoring of the reactions was conducted by high performance liquid chromatography (HPLC) after derivatization by 1-fluoro-2,4-dinitrobenzene. Straightforward purification by solid-phase extraction (SPE) afforded the amino alcohols with excellent yields (93% to &#62;95%).

Chiral amino alcohols are versatile molecules for use as scaffolds in organic synthesis. Starting from L-lysine, we synthesize amino alcohols by an enzymatic cascade reaction combining diastereoselective C-H oxidation catalyzed by dioxygenase followed by cleavage of the carboxylic acid moiety of the corresponding hydroxyl amino acid by a decarboxylase.

酶联反应合成 l-赖氨酸手性氨基醇的研究

Amino alcohols are versatile compounds with a wide range of applications. For instance, they have been used as chiral scaffolds in organic synthesis. ...

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

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

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

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

苷 2 ', 3 ' -二醇酯对双糖苷合成的选择性O-糖基化

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

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of &#945;-Imino &#947;-Lactones and Alkylidene Pyrazolones

Bispirocyclic scaffolds are one of the important structural subunits in many natural products that exhibit diverse and attractive biological activities. Recently, we have developed an efficient organocatalytic strategy, which provides facile access to a variety of enantiomerically enriched bispiro[&#947;-butyrolactone-pyrrolidin-4,4&#39;-pyrazolone] skeletons. In this paper, we demonstrate a detailed protocol for the asymmetric synthesis of drug-like bispirocyclic compounds with two spirocyclic carbon centers via an organocatyltic 1,3-dipolar cycloaddition reaction. Spirocyclization synthons &#945;-imino &#947;-lactones and alkylidene pyrazolones are prepared first, which are then subjected to a cycloaddition reaction in the presence of a bifunctional squaramide organocatalyst to afford the desired bispirocycles in high yields and excellent stereoselectivities. Chiral high-performance liquid chromatography (HPLC) is carried out to determine the enantiomeric purity of the products, and the d.r. value is examined by proton nuclear magnetic resonance (1H NMR). The absolute configuration of the product is assigned according to an X-ray crystallographic analysis. This synthetic strategy allows scientists to prepare a diversity of bispirocyclic scaffolds in high yields and excellent diastereo- and enantioselectivities.

Enantiomerically enriched bispiro[&#947;-butyrolactone-pyrrolidin-4,4&#39;-pyrazolone] skeletons are asymmetrically synthesized through a simple organocatalytic 1,3-dipolar cycloaddition reaction.

α-伊米诺γ-乳胶酮和阿基地利酮吡唑酮有机催化环加花法高效构建药物样双环脚手架

Bispirocyclic scaffolds are one of the important structural subunits in many natural products that exhibit diverse and attractive biological activities. ...

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

We introduced a regioselective and atom-economical procedure for the synthesis of 3-substituted indoles by annulation of nitrosoarenes with ethynyl ketones. The reactions were carried out achieving indoles without any catalyst and with excellent regioselectivity. No traces of 2-aroylindole products were detected. Working with 4-nitronitrosobenzene as starting material, the 3-aroyl-N-hydroxy-5-nitroindole products precipitated from the reaction mixtures and were isolated by filtration without any further purification technique. Differently from the corresponding N-hydroxy-3-aryl indoles that, spontaneously in solution, give dehydrodimerization products, the N-hydroxy-3-aroyl indoles are stable and no dimerization compounds were observed.

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

3-Aroyl-N-hydroxy-5-nitroindoles were synthesized by cycloaddition of 4-nitronitrosobenzene with a conjugated terminal alkynone in a one-step thermal procedure. Preparation of the nitrosoarene and of the alkynones were adequately reported and respectively through oxidation procedures on the corresponding aniline and on the alkynol.

A 直接、再生和原子经济合成3-Aroyl-N-羟基-5-硝基胺基，通过环加4-硝基苯与烷基诺

We introduced a regioselective and atom-economical procedure for the synthesis of 3-substituted indoles by annulation of nitrosoarenes with ethynyl ...

Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly

This protocol presents the use of Lewis acidic multi-role reagents to circumvent kinetic trapping observed during the self-assembly of information-encoded oligomeric strands mediated by paired dynamic covalent interactions in a manner mimicking the thermal cycling commonly employed for the self-assembly of complementary nucleic acid sequences. Primary amine monomers bearing aldehyde and amine pendant moieties are functionalized with orthogonal protecting groups for use as dynamic covalent reactant pairs. Using a modified automated peptide synthesizer, the primary amine monomers are encoded into oligo(peptoid) strands through solid-phase submonomer synthesis. Upon purification by high-performance liquid chromatography (HPLC) and characterization by electrospray ionization mass spectrometry (ESI-MS), sequence-specific oligomers are subjected to high-loading of a Lewis acidic rare-earth metal triflate which both deprotects the aldehyde moieties and affects the reactant pair equilibrium such that strands completely dissociate. Subsequently, a fraction of the Lewis acid is extracted, enabling annealing of complementary sequence-specific strands to form information-encoded molecular ladders characterized by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). The simple procedure outlined in this report circumvents kinetic traps commonly experienced in the field of dynamic covalent assembly and serves as a platform for the future design of robust, complex architectures.

A protocol is presented for the synthesis of information-encoded peptoid oligomers and for the sequence-directed self-assembly of these peptoids into molecular ladders using amines and aldehydes as dynamic covalent reactant pairs and Lewis acidic rare-earth metal triflates as multi-role reagents.

信息承载Peptoids及其序列定向动态共价自组装的合成

This protocol presents the use of Lewis acidic multi-role reagents to circumvent kinetic trapping observed during the self-assembly of information-encoded ...