删除或更新信息,请邮件至freekaoyan#163.com(#换成@)

可见光驱使铜盐催化芳香烃二氟烷基化反应

本站小编 Free考研考试/2022-02-14

摘要/Abstract



以CuI为铜源, 通过原位形成光催化剂的途径, 实现了室温下可见光驱使铜催化溴二氟乙酸乙酯、溴二氟酰胺等对芳烃及杂芳烃的二氟烷基化反应. 该反应条件温和、原料廉价易得、底物适用范围广、产率较高, 为合成二氟烷基(杂)芳烃化合物提供了一种方法. 机理研究表明, 该反应可能经历了单电子转移的自由基反应历程.
关键词: 烷基自由基, 可见光催化, 二氟烷基化反应, 芳烃,
The introduction of difluoromethyl groups into organic molecules not only can dramatically alter physical properties of nonfluorinated counterparts, but also provide valuable CF2-containing building blocks for the synthesis of other difluoromethylenated compounds. Therefore, there is a growing demand to develop efficient and practical methods for the introduction of the difluoromethyl motif. Although significant advances have been made in the preparation of difluoromethylated arenes, these reactions usually required pre-functionalized substrates, precious metal catalysts, elevated temperature, and so on. In the past decade, visible light-driven photoredox catalysis has been proved to be powerful in synthetic radical chemistry. Particularly, direct difluoroalkylations of arenes have been achieved using precious-metal photocatalysts such as ruthenium or iridium polypyridyl complexes. Herein, we are committed to developing a cheap copper-based phororedox system for direct difluoroalkylation of arenes. The key to this approach is the in-situ formation of cuprous photocatalyst from cuprous iodide, an imine ligand (2,9-dichloro-1,10-phenanthroline) and a triaryl phosphine ligand (4,5-bis(diphenylphos- phino)-9,9-dimethyl xanthene). With catalytic amount of reagents mentioned above, the direct difluoroalkylation between arenes and difluoroalkylation reagents (BrCF2CO2Et or BrCF2CONR 1R 2) took place smoothly under 6 W blue LED irradiation at room temperature. A variety of electron-rich arenes, including electron-donating aromatics, indoles, furans, thiophenes, and pyrimidines, could be carbonyldifluoromethylated in moderate to excellent yields. In addition, high yields were obtained for the intramolecular and intermolecular aminocarbonyldifluoromethylation by the catalytic system. Preliminary mechanistic studies reveal that [Cu(dcp)(xantphos)]I (dcp=2,9-dichloro-1,10-phenanthroline, xantphos=4,5-bis(diphenyl phosphino)-9,9-dimethyl xanthene), in situ-formed from CuI, dcp, and xantphos should be the real photocatalyst to catalyze the visible light-driven difluoroalkylation. Difluormethyl radicals, produced by single electron transfer from the excited photocatalyst to difluoroalkylation reagents, should be involved in the difluoroalkylation. In summary, visible-light driven difluoroalkylation of arenes with difluoroalkylation reagents via Cu-catalysis has been developed. The use of the bidentate phosphine ligand and the imine ligand is essential for high efficiency as they could bind to cuprous iodide to generate the photocatalyst in situ. The typical procedure is as follows: a mixture of arenes (0.6 mmol), CuI (0.02 mmol), dcp (0.02 mmol), xantphos (0.02 mmol), K3PO4 (0.4 mmol) and CH2Cl2 (2 mL) were loaded in a flame-dried reaction vial which was subjected to evacuation with argon for 30 min. Subsequently, BrCF2CO2Et (0.2 mmol) was added to the mixture via syringe, and the mixture continued degassing for 5 min. After degassing procedure, the vial was sealed with wax, and irradiated by blue light for 24 h. The reaction was monitored by TLC. Further purification of the evaporated mixture by flash column chromatography on silica gel (eluent: petroleum ether/ethyl acetate) gave the desired product.
Key words: alkyl radical, visible-light photocatalysis, difluoroalkylation, arenes, copper


PDF全文下载地址:

点我下载PDF
相关话题/电子 芳烃 可见光 烷基 乙酸乙酯

  • 领限时大额优惠券,享本站正版考研考试资料!
    大额优惠券
    优惠券领取后72小时内有效,10万种最新考研考试考证类电子打印资料任你选。涵盖全国500余所院校考研专业课、200多种职业资格考试、1100多种经典教材,产品类型包含电子书、题库、全套资料以及视频,无论您是考研复习、考证刷题,还是考前冲刺等,不同类型的产品可满足您学习上的不同需求。 ...
    本站小编 Free壹佰分学习网 2022-09-19
  • 具有分级纳米结构的In2S3/CdIn2S4在可见光下催化苯甲胺的氧化偶联反应
    摘要/Abstract采用以太阳光为能源、半导体材料为催化剂的催化体系将胺类化合物转化为相应的亚胺类化合物的方法是一种理想的有机合成手段.为了探索这类反应更温和的反应条件及更清晰的反应机理,本工作以NH2-MIL-68(In)和硫脲为前驱体制备了In2S3分级纳米管,并进一步采用热离子交换的方法制备 ...
    本站小编 Free考研考试 2022-02-14
  • 分子电子学的新进展
    摘要/Abstract分子尺度电子学通过构筑基于微尺度电极和单个分子或者少量分子聚集体的"电极-分子-电极"结,研究跨越分子的电荷输运性质.它将分子本征化学特性与器件构筑相结合,考察分子的理化特性与电荷输运的构效关系,揭示微尺度的量子输运动力学原理,并探索基于分子的功能电子器件.是一个集化学、物理学 ...
    本站小编 Free考研考试 2022-02-14
  • 4-硫代尿嘧啶与色氨酸光致电子转移反应研究
    摘要/AbstractRNA与蛋白质相互作用是生物体进行生命活动的基础,光活化核苷酸引发的共价交联是研究其相互作用的有效手段.对其机理的研究有助于理解并调控交联的位点及氨基酸,因此探测关键的中间体来揭示机理很有必要.本工作选择光活化核苷酸4-硫代尿嘧啶(4-TU)和色氨酸(TrpH)为模型体系,通过 ...
    本站小编 Free考研考试 2022-02-14
  • BiOCl-ov/坡缕石复合可见光催化剂的制备及其对醇类的选择性氧化研究
    摘要/Abstract采用简单的一步水热法,制备了一系列BiOCl-ov/坡缕石(PGS)复合材料xB/P(x是复合材料中BiOCl-ov的摩尔含量).通过扫描电子显微镜(SEM)、粉末X射线衍射(XRD)、X射线光电子能谱(XPS)、N2吸附-脱附、红外光谱(FT-IR)、紫外-可见漫反射光谱(U ...
    本站小编 Free考研考试 2022-02-14
  • 以UiO-66为前驱体的Fe-ZrO2的制备及其可见光降解性能研究
    摘要/Abstract金属有机骨架(UiO-66)具有大的比表面积和强的吸附能力,且金属锆离子高度有序地排列在框架中.先采用UiO-66的结构特点使其吸附Fe3+,再通过煅烧前驱体Fe3+/UiO-66的方法成功制备出Fe掺杂的ZrO2纳米光催化剂Fe-ZrO2.通过扫描电子显微镜(SEM)、X射线 ...
    本站小编 Free考研考试 2022-02-14
  • 电子捕获裂解质谱研究进展
    摘要/Abstract过去的二十年中,以电子捕获裂解为代表的离子反应技术,极大地推动了气相自由基离子化学的研究.该领域的发展是现代质谱的前沿问题,同时也是后基因组时代生物分析的重要技术手段.总结了电子捕获裂解的研究进展,并对其产生、裂解规律以及机理的研究进行了详细的综述.关键词:质谱,电子捕获裂解, ...
    本站小编 Free考研考试 2022-02-14
  • 镍催化氟代烯基硼酯与烷基卤化物Suzuki偶联反应
    摘要/Abstract有机化合物特定位点嵌入氟原子或含氟片段,可以产生独特的生物或物理性质改变.单氟取代烯基是生物医药领域理想的酰胺键替代物,在医药化学、药物研发等方向已经获得广泛的应用.通过溴化镍(Ⅱ)二乙二醇二甲醚复合物、4,4'-二叔丁基-2,2'-二吡啶的催化体系,实现了多种氟代烯基硼酯与一 ...
    本站小编 Free考研考试 2022-02-14
  • 铁催化下二芳基锌和芳基格氏试剂的二氟烷基化反应
    摘要/Abstract随着医药、农药、材料等领域对含氟化合物日益增长的需求,发展向有机分子中直接引入氟原子和含氟基团的方法受到了化学家们的广泛重视.近些年来,过渡金属催化的氟烷基化反应,作为一种温和可控向有机分子引入含氟基团的策略得到了快速发展.与此同时,从反应的高效简洁和绿色温和性角度出发,发展廉 ...
    本站小编 Free考研考试 2022-02-14
  • 1,4-二烯和醛的烯丙基碳氢不对称烷基化反应
    摘要/Abstract利用钯配合物、有机胺和手性布朗斯特酸三元催化剂体系实现了-取代丙醛参与的1,4-二烯烃的烯丙基碳氢不对称烷基化反应,以良好的产率、优良的区域选择性和立体选择性得到了结构多样的手性-羰基化合物.此外发现非手性膦配体对钯配合物的催化活性和反应的选择性有十 ...
    本站小编 Free考研考试 2022-02-14
  • HOMO活化的2-吡喃酮与2,5-二烯酮反电子需求的不对称Diels-Alder反应
    摘要/Abstract2-吡喃酮的不对称Diels-Alder(DA)反应可以高效、高立体选择性地构建多官能团化的双环内酯手性骨架.目前贫电子的2-吡喃酮多依赖于手性Lewis酸通过降低LUMO能量与富电子烯烃发生反电子需求环加成反应,活化机制相对单一,因此发展新的活化模式合成此类骨架尤为重要.报道 ...
    本站小编 Free考研考试 2022-02-14