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

四氢咔唑氢过氧化物1。合成<ol><li>氢过氧化物的形成变慢，如果四氢非常着色。在这种情况下，用甲苯/戊烷重结晶或通过柱色谱法纯化它得到一个无色的原料。对于通过柱层析纯化，包有硅胶的下层和氧化铝的上层的柱。把四氢在柱顶部和洗脱用甲苯。所有不需要的黄色和黑色的有色副产物被吸附在柱和无色四氢被洗脱。立即使溶剂蒸发和氩在黑暗的环境下储存纯的白色产物。 </li><li>称量1g的取代的四氢咔唑的四氢咔唑或（1，根据报道的方法合成的16）放入250毫升烧瓶中。加入100 ml甲苯中，此烧瓶中。 </li><li>称取玫瑰红（2毫克）并将其加入到上述反应混合物中。 </li><li>添加搅拌棒和覆盖隔烧瓶。 </li><li>加穿过隔膜的氧气球;这样可以使氧气气氛对反应的正压力。 </li><li>以23瓦的灯照射反应混合物中。 </li><li>检查用薄层色谱法对反应的进展（薄层色谱法，使用己烷/乙酸乙酯的混合物中的比例为70:30;本文所述的氢过氧化物的R F值介于0.2和0.3），或通过1 H-NMR从取试样（使溶剂蒸发用旋转蒸发器，并溶解在DMSO-d6的残基）。反应时间可根据不同的光源和起始材料的纯度而变化，正如在部分1.1。一般来说，四氢咔唑1全数转换需要3小时。 </li><li>原料获悉数转换后，过滤沉淀的固体。固体的洗涤可以用戊烷，以除去大部分完成甲苯，但没有必要进行纯化。 </li><li>干燥，减压分离的固体。 </li></ol>注意：虽然我们从来没有经历过任何问题与工作或处理在这项工作中所描述的化合物，预防措施应与过氧化物工作时服用。尤其是，应当避免，因为尽可能地暴露整齐过氧化物进行加热或与金属或金属盐混合。后面的防爆屏蔽进行这样的反应，建议。 2，偶联反应 - 方法A在使用甲醇10％（摩尔）三氟乙酸<ol><li>称出的过氧化氢（0.49毫摩尔，1.0当量来自步骤1）和所需的苯胺亲核试剂（0.49毫摩尔，1.0当量）到一个12 ml小瓶或合适的圆底烧瓶中。 </li><li>加入10 ml甲醇，并随后3.74微升三氟乙酸（TFA，0.049毫摩尔，0.1当量）的小瓶或圆底烧瓶中。 </li><li>关闭容器用盖和在室温下搅拌4小时搅拌反应混合物。 后处理变体A1（对于其中沉淀在反应过程中的产品）： </li><li>过滤析出的固体，以得到所需的产物。用甲醇（3×0.5毫升）洗涤产物。 </li><li>获得产品的第二部分，蒸发从滤液中的甲醇。将粗产物溶解在5ml乙酸乙酯中，在40℃，然后冷却至室温，并加入3-5戊烷的纯产物沉淀毫升。 </li><li>结合产品的不同部分和干他们在高真空下。 后处理变型A2（产品不沉淀）： </li><li>通过使用旋转蒸发器将反应后直接蒸发溶剂，并指定（硅胶，己烷/乙酸乙酯/三乙胺）纯化，得到期望的产物用柱色谱法纯化残余物。 </li></ol> 3偶联反应 - 方法B使用乙酸<ol><li>称出的过氧化氢（0.49毫摩尔，1.0当量来自步骤1）和所需的苯胺亲核试剂（0.49毫摩尔，1.0当量）到一个12 ml小瓶或合适的圆底烧瓶中。 </li><li>加入10 ml乙酸（AcOH）将与药瓶或圆底烧瓶中。 </li><li>关闭容器用盖，并在室温下搅拌4小时，搅拌反应混合物。 后处理变体B1（使沉淀在反应过程中的产品）： </li><li>过滤析出的固体，以得到所需的产物。用AcOH（3×0.5ml）的洗涤产品。 </li><li>获得产品的第二部分，蒸除乙酸从滤液。将粗产物溶解在5ml乙酸乙酯中，在40℃，然后冷却至室温，并加入3-5戊烷的纯产物沉淀毫升。 </li><li>结合产品的不同部分和干他们在高真空下。 后处理变种B2 </str翁&gt;（产品不沉淀）： </li><li>通过使用旋转蒸发器将反应后直接蒸发溶剂，并指定（硅胶，己烷/乙酸乙酯/三乙胺）纯化，得到期望的产物用柱色谱法纯化残余物。 </li></ol>

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作者什么都没有透露。

综上所述，我们能够证明在四氢咔唑CH键可以方便地官能化，以产生CN-偶联产物的两步骤程序中。 第一步是四氢咔唑（1）或其与元素氧17,19衍生物的公知的光催化氧化反应，使氢过氧化物2。如果在甲苯中进行的，氢过氧化物产物沉淀，并且可以很方便地通过过滤分离。进一步纯化不是必要的。 第二个步骤是酸催化的亲核...

CH键的直接官能是在有机化学1一项重要而长期的目标。这种转变可以是非常强大的，以便通过节省步骤，时间和材料相比，需要激活或指挥团的导入和去除传统的方法来简化合成。因此，CH键的功能化也是绿色化学2的吸引力。下的氧化的条件下，2 CH键或1 CH和一个杂原子-H键可以转换到CC和C-杂原子键，分别为（ 图1）3-9。通常，这些氧化偶联反应需要合成氧化剂，昂贵的催化剂或高温。因此，很多次尝试，开发使用廉价的催化剂，良性的条件和氧气或空气作为氧化剂终端10个方法。 <img alt="图1" fo:content-wIDþ=“5英寸”SRC =“/ files/ftp_upload/51504/51504fig1highres.jpg”宽度=“500”/&gt; 图1。氧化偶联反应。 <a href="https://www.jove.com/files/ftp_upload/51504/51504fig1highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 许多有机化合物反应缓慢与氧从空气中自动氧化反应，这可以通过有效地插入O 2，形成氢过氧化物基团功能化11,12 CH键。自氧化过程是用在工业规模上，以从烃原料生成的含氧化合物，但是自氧化也是不希望的过程，如果它导致了有价值的化合物或材料分解。在某些情况下，例如乙醚，在空气中形成过氧化氢也可以是爆炸性的。近来，我们发现了一种反应，利用一个自动氧化，形成由CH键的新的C-C键，而不需要氧化还原活性的催化剂13,14的</SUP&gt;。简单地在酸催化剂的存在下搅拌氧基板导致新产品的形成。键的反应是容易形成中间氢过氧化物，其通过酸催化15被取代的与第二基板的。该反应，但是，仅限于呫吨及被轻易氧和产品的气氛下被氧化的几个相关化合物具有迄今未发现的应用程序。这一发现启发然而，我们开发，利用CH功能化的原则通过中级过氧化物（CHIPS），合成药物活性吲哚衍生物16与氧化偶联方法。 吲哚类化合物，特别是四氢咔唑1，可以很容易地被氧化成氢过氧化物2中的单线态氧17〜19，可以使用增感剂和可见光20产生的存在。一个HYDRoperoxide部分原则上可以作为是否通过酸催化活性，并允许引入亲核试剂21,22离去基团。过氧化氢 ​​也是已知的经过酸催化重排反应，如在工业合成苯酚的从异丙苯，Hock方法23利用。通过仔细的优化研究，我们可以找到条件有利于与N-亲核试剂像苯胺3在不需要的分解途径被重排16所希望的取代反应。在这里，我们描述了这两个步骤的CHIPS过程详细地说，只使用可见光，敏化剂，氧和酸。其中所选择的产品是吲哚衍生物4，它显示出高的抗病毒活性或抑制血管内皮生长因子（VGF），这可能是重要的肿瘤治疗24-26。

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

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

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

合成1 - （5 -硝基吲哚啉-1 -基）-2,3,4,9 -四氢-1H-咔唑（图4a）： 根据方法A，R F = 0.63（己烷/乙酸乙酯70:30）合成。 净化 ：用方法A，后处理变量A1净化产品（步骤2.4，2.5，2.6）。橙色固体，产率：95％。 1 H NMR（500兆赫，DMSO-D6）：δ10.90（s，1H），7.97（日，J</...

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

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

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

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 ...

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

Unit 1

Acids and Bases

SCIENTISTS IN ACTION

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

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

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

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

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

抗癌金属配合物的合成与细胞毒性评价MTT法

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

科研

化学

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

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

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

合成，表征和混合金/硫化镉和Au / ZnS核/壳纳米颗粒功能化

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

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

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

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

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

协议的合成<em&gt;邻</em&gt; -trifluoromethoxylated苯胺类化合物

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

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

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

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

单壁碳纳米管与热可逆嵌段共聚物及表征功能化小角度中子散射

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

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

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

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

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

蛋白质生物缀合物的合成<em&gt;通过</em&gt;半胱氨酸马来酰亚胺化学

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

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

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

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

通过活性表面生长机制合成基片束缚金纳米线

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

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

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

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

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

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 ...

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

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

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

Enolonium 种极性转换酮功能化的两步协议

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

Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance

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

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

金属-有机框架的表面功能化改善防潮性能

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

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile

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

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

乙腈绿色 Steglich 酯化合成酯的研究

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