取代邻羟基苯乙酮的简便绿色合成

以对甲(氯、溴)苯酚(1a-c)为起始原料经酰化得对甲(氯、溴)苯酚乙酯,再以BF3·2HAc为催化剂无溶剂条件下实现Fries重排,以77.3%-80.4%的收率分别得到了5-甲基(氯、溴)邻羟基苯乙酮(2a-c);应用环境友好的聚乙二醇-400为溶剂,N-氯(溴、碘)代丁二酰亚胺为卤代试剂对邻羟基苯乙酮进行卤代反应,以61.8%-92.4%的收率制备3,5-二氯(溴、碘)邻羟基苯乙酮(4a-c);以邻羟基苯乙酮为原料,硝酸铈铵(CAN)为绿色硝化试剂,分别以29.8%和63.9%的收率得到了3位和5位硝化产物1-(2-羟基-3-硝基苯基)乙酮、1-(2-羟基-5-硝基苯基)乙酮(5a-b)。以上制备过程具有反应条件温和、后处理简单、环境友好等优点,为制备取代邻羟基苯乙酮提供了简单且绿色的新方法。     

邻羟基苄醇与邻羟基苯乙烯的催化不对称[4+2]环加成反应——手性色满骨架的立体选择性构建

研究了手性磷酸催化下邻羟基苄醇和邻羟基苯乙烯的不对称［4+2］环加成反应,立体选择性地一步构建了手性2,4-二取代四氢色满骨架,该反应具有较高的收率、中等到较高的对映选择性和很好的非对映选择性（最高产率为78%,最高ee值为72%,dr值基本都大于95∶5）.带有不同取代基的多种邻羟基苄醇和邻羟基苯乙烯均适用于该反应,电子效应对于该反应的对映选择性有一定影响,其中连有供电子基的底物具有更高的反应活性和对映选择性.由邻羟基苄醇原位生成的邻亚甲基苯醌中间体和邻羟基苯乙烯可以同时与催化剂手性磷酸形成双重氢键,对于促进反应的进行和控制该反应的对映选择性起着至关重要的作用.     

Sc(Ⅲ)催化胺对邻亚甲基苯醌氮杂迈克尔加成反应合成贝蒂碱衍生物

邻亚甲基苯醌化合物是一类非常活泼和重要的中间体,被广泛应用于天然产物和药物化学中.以2-[羟基(苯基)甲基]苯酚类化合物和胺为原料,1,2-二氯乙烷为溶剂,在Sc(III)促进下原位生成邻亚甲基苯醌,并发生氮杂迈克尔加成反应合成贝蒂碱衍生物.反应在封管条件下90℃搅拌4 h完成,以76%～96%的产率得到目标产物.     

电化学共聚邻甲基苯胺和邻氨基苯甲酸的在线紫外-可见光谱的研究

在0.5 mol/L H₂SO₄水溶液中, 以氧化铟锡(ITO)导电玻璃为工作电极, 用恒电位电解的方法, 在0.9 V电位下电化学共聚邻甲基苯胺(OT)和邻氨基苯甲酸(AA). 涉及的电化学聚合均用在线紫外-可见光谱进行跟踪, 结果表明电化学共聚随着反应体系中邻氨基苯甲酸的浓度的增加而变慢; 所得的均聚物和共聚物均用FTIR和扫描电镜表征. FTIR表明邻甲基苯胺和邻氨基苯甲酸之间发生了共聚; 扫描电镜图表明, 与聚邻甲基苯胺相比, 从200 mmol/L OT/50 mmol/L AA和150 mmol/L OT/50 mmol/L AA反应体系得到的共聚物具有小颗粒和较为致密的表面形貌; 这个现象也帮助证明了邻氨基苯甲酸应该与邻甲基苯胺发生了共聚, 并使表面形貌发生了改变.     

无外加催化剂条件下邻取代芳香醛与5,5-二甲基-1,3-环己二酮的反应研究

在DMF溶剂中,不外加催化剂使邻取代芳香醛(1)与5,5-二甲基-1,3-环己三酮(2)发生缩合和加成反应生成3,3,6,6-四甲基-4a-羟基-9-芳基-1,8二氧化-2,3,4,4a,5,6,7,8,9a-十氢化-1H氧杂蒽(3a～3d)。在同样条件下,邻羟基芳香醛与5,5-二甲基-1,3-环己三酮则发生缩合,加成和脱水反应生成3,3-二甲基-9-(5,5-二甲基-3-羟基-2-环己烯-1-酮-2-基)-1-氧代-2,3,4,9-四氢化-1 氧杂蒽(4a～4b)。用单晶X-射线分析法确定了产物3a和4a的晶体结构。     

2/3-取代硫基-5-邻羟基苯基唑类化合物的合成及抑菌活性

根据生物活性叠加原理,将"邻羟基苯基"和"唑类杂环"分子片断合理组合,设计合成了三个系列12种新型2/3-取代硫基-5-邻羟基苯基唑类化合物5a～7d.水杨酸甲酯在乙醇中与水合肼反应生成水杨酰肼,水杨酰肼与二硫化碳或硫氰酸铵和盐酸反应,生成5-邻羟基苯基-1,3,4-噁二唑-2-硫酮(2),5-邻羟基苯基-1,3,4-噻二唑-2-硫酮(3)和5-邻羟基苯基-4H-1,2,4-三唑-3-硫酮(4),最后在碱性条件下与(取代)卤代苯乙酮发生烷基化反应生成目标化合物.目标化合物的结构经1HNMR,IR和元素分析等表征确认.抑菌测试表明,质量浓度为0.01%时,对白色念珠菌、大肠杆菌的抑菌率高达92%以上,具有强抑菌活性;对金黄色葡萄球菌抑菌率高达82%以上,具有较强的抑菌活性;这表明目标化合物对不同菌株具有广谱抑菌活性,是一类极具潜力的抗真菌、抗革兰氏阴性菌化合物.构效分析表明,苯乙酮环上取代基的类型对化合物抑菌活性有重要影响,引入Cl,Br等卤原子,能显著增强化合物的抑菌活性,而引入CH3供电基团,能降低其抑菌活性.     

无外加催化剂条件下邻取代芳香醛与5, 5-二甲基-1, 3-环己二 酮的反应研究

在DMF溶剂中,不外加催化剂使邻取代芳香醛(1)与5,5-二甲基-1,3-环己二酮(2)发生缩合和加成反应生成3,3,6,6-四甲基-4a-羟基-9-芳基-1,8-二氧代-2,3,4,4a,5,6,7,8,9,9a-十氢化-1H-氧杂蒽(3a-3d)。在同样条件下,邻羟基芳香醛与5,5-二甲基-1,3-环己二酮则发生缩合、加成和脱水反应生成3,3-二甲基-9-(5,5-二甲基-3-羟基-2-环己烯-1-酮-2-基)-1-氧代-2,3,4,9-四氢化-1-氧杂蒽(4a-4b)。用单晶X-射线分析法确定了产物3a和4a的晶体结构。     

邻香兰素对甲苯胺Schiff碱稀土配合物的制备和表征

前文曾报道了香兰素(3-甲氧基-4-羟基苯甲醛)与对甲基苯胺的Schiff碱稀土配合物。本文讨论邻香兰素(2-羟基-3-甲氧基苯甲醛)与对甲基苯胺的Schiff碱稀土配合物[LnL_2Cl·2H_2O]Cl_2(Ln:ce,Pr,Nd,Sm,Eu,Gd,Dy;L:Schiff碱)的制备和表征。 1 实验 1.1 配合物的制备 按文献方法,用等摩尔比的邻香兰素与对甲基苯胺在无水乙醇中先制成Schiff碱,然后按摩尔比1:2将稀土氯化物LnCl_3·nH_2O的无水乙醇溶液滴加到     

乙酸促进邻甲基苯磺酸铜选择性催化醇和酚的四氢吡喃化反应

室温无溶剂条件下, 乙酸能有效促进邻甲基苯磺酸铜催化一系列醇或酚和3,4-2H-二氢吡喃反应, 生成相应的四氢吡喃醚. 在乙酸存在条件下, 体系的催化性能有显著提高, 邻甲基苯磺酸铜用量仅需0.3 mol%(占醇或酚的摩尔分数)就能使反应在较短时间内完成. 反应结束后, 邻甲基苯磺酸铜经简单相分离可多次重复使用, 催化活性无明显下降. 产物结构经IR, 1H NMR, 元素分析进行表征.     

邻羟基α-叠氮苯乙酮衍生物的合成

以邻羟基苯乙酮衍生物为原料,经溴化反应和叠氮化反应合成了一系列邻羟基α-叠氮苯乙酮衍生物,其结构经1H NMR,13C NMR,IR及HR-MS表征.     

ALIPHATIC THIOETHERS BY S-ALKYLATION OF THIOLS VIA TRIALKYL BORATES

A simple and convenient one-pot procedure is described for the synthesis of thioethers via boron esters. This procedure involves in-situ generation of alkyl sulfates by reaction of trialkyl borates with concentrated sulfuric acid and subsequent reaction with thiols in the presence of pyridine. The reactions with boron esters of primary or secondary alcohols proceed cleanly at 100°C and afford aliphatic thioethers in reasonable yields (59–93%) within 24 h. Interestingly, the ¹H NMR spectra of the products showed no sign of positional isomerisms. The method fails however with thiophenol and does not yield aromatic thioethers, due to electrophilic substitution at the phenyl ring.     

Direct Synthesis of Allylic Thioethers Under Greener Conditions: A Solvent- and Catalyst-Free Approach

We present herein a new catalyst-free and solvent-free approach for the synthesis of allylic thioethers directly from allylic alcohols and thiols. The methodology allows the synthesis of different allylic thioethers in good to excellent yields under microwave irradiation. Theoretical calculations for the allylic carbocation helped to explain the regioselectivity observed when nonsymmetric substrates are used in the reaction.     

(Cyanomethyl)trimethylphosphonium iodide as reagent for the intermolecular S-alkylation of thiols with alcohols

Treatment of mixtures of thiols and primary aliphatic alcohols with (cyanomethyl)trimethylphosphonium iodide leads to the clean formation of unsymmetric thioethers. The required phosphonium iodide is simple to prepare and stable towards air and moisture. This new synthesis of thioethers yields crude products of high purity and should be suitable for parallel solution-phase chemistry.     

Synthesis of Cleavable Polymers via Oxidation of Thioether Moieties and Thiol Click Reactions: A Click-Declick Strategy

In the past decades click chemistries including thiol chemistries have found wide applications in the synthesis of well-defined polymers. In this research, a click-declick strategy based on the oxidation of heteroaromatic thioethers and the substitution reactions between the oxidized groups and thiols, is proposed for the synthesis of the cleavable polymers. In proof-of-concept experiments, block copolymers (BCPs) and star-like polymers are synthesized by thiol-phenylsulfone substitution reactions, and heteroaromatic thioethers are produced at the junction points of the BCP chains or on the crosslinking sites of the star-like polymer. The thioethers can be oxidized to heteroaromatic sulfoxides or sulfones, depending on the oxidization condition. It is demonstrated that both sulfoxides or sulfones can have base catalyzed nucleophilic substitution reactions with thiols, leading to the cleavage of the polymers.     

Transition‐Metal‐Catalyzed CS Bond Coupling Reaction

Sulfur‐containing molecules such as thioethers are commonly found in chemical biology, organic synthesis, and materials chemistry. While many reliable methods have been developed for preparing these compounds, harsh reaction conditions are usually required in the traditional methods. The transition metals have been applied in this field, and the palladium‐catalyzed coupling of thiols with aryl halides and pseudo halides is one of the most important methods in the synthesis of thioethers. Other metals have also been used for the same purpose. Here, we summarize recent efforts in metal‐catalyzed C? S bond cross‐coupling reactions, focusing especially on the coupling of thiols with aryl‐ and vinyl halides based on different metals.     

Identification of microbial inhibitory functional groups in corn stover hydrolysate by carbon-13 nuclear magnetic resonance spectroscopy

Dilute-acid biomass hydrolysates contain biomass degradation products that are inhibitory to cell growth and fermentation. Overliming with Ca(OH)₂ has been found to be one of the most effective methods for detoxifying the dilute-acid hydrolysate for ethanol production. However, the mechanism of overliming is not well understood. Carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopy was used to elucidate the functional groups involved in the overliming reaction. The ¹³C-NMR spectra showed that the major functional groups removed during the overliming process were aliphatic and aromatic acids or esters, and other aromatic and aliphatic compounds. Ketone and aldehyde functionalities were not detected in the spectra. This is the first time that ¹³C-NMR has been used to elucidate the overliming reaction.     

An Efficient and Odorless Synthesis of Thioethers Using 2‐[Bis(alkylthio)methylene]‐3‐oxo‐N‐o‐tolylbutanamides as Thiol Equivalents

Using 2‐[bis(alkylthio)methylene]‐3‐oxo‐N‐o‐tolylbutanamides 1 as odorless thiol equivalents, an efficient and odorless synthesis of thioethers has been developed. Promoted by NaOH in EtOH, the cleavage of 1 commences to generate thiolate anions, and the generated thiolate anions then react with halides to give various thioethers in good yield. It is noteworthy that only a very faint odor of thiols can be perceived during both the reaction and the workup.     

Lewis acid-catalyzed, copper(II)-mediated synthesis of heteroaryl thioethers under base-free conditions

A Lewis acid (Ag(I), Ni(II), or Fe(II)) catalyzed, Cu(II)-mediated thiolation reaction between heteroarenes and thiols was achieved with good yield under base-free conditions. DMSO could serve as an effective methylthiolation reagent for the synthesis of heterocyclic methyl thioethers.     

Preparation and properties of phenyl‐modified natural rubber

We prepared phenyl‐modified natural rubber using a two‐step process. In the first step, natural rubber was brominated using N‐bromosuccinimide in a dichloromethane solution of natural rubber. The amount of N‐bromosuccinimide controlled the bromine content. In the second step, a Suzuki–Miyaura cross‐coupling reaction of the brominated natural rubber with phenyl boronic acid in the presence of a palladium catalyst replaced the bromine atoms with phenyl groups. ¹H‐nuclear magnetic resonance and ¹³C‐nuclear magnetic resonance measurements characterized the products. The signals around 7 ppm in the ¹H‐nuclear magnetic resonance spectra of the products were assigned to the phenyl protons, and based on the assigned signals, the estimated conversion of the cross‐coupling reaction under mild conditions was more than 70 mol%. The amount of phenyl groups present affected both the loss tangent and the glass transition temperature of natural rubber, which increases from ?62°C to ?30°C. Copyright © 2015 John Wiley & Sons, Ltd.     

An efficient intermolecular C(aryl)-S bond forming reaction catalyzed by BINAM-copper(II) complex

A wide range of diaryl thioethers and aryl alkyl thioethers are synthesized from the corresponding aryl iodides and aromatic/aliphatic thiols through Ullmann type intermolecular coupling reactions in the presence of a catalytic amount of easily available BINAM-Cu(OTf)₂ complex. Less reactive aryl bromides have also been shown to react with thiols under identical reaction conditions to give good yields of the thioethers without increasing the reaction temperature and time.