新兴的人工光开关催化领域最近展示了功能性光响应系统的惊人例子,允许动态控制有机催化和金属催化转化中的活性和选择性。虽然我们小组已经公开了以第一代分子马达作为可切换中心核心的系统,但缺乏基于第二代分子马达的设计。在这里,报道了基于光响应性四取代烯烃核心的两个双功能化分子开关的合成。它们在上半部分具有硫脲取代基作为供氢部分,在下半部分具有碱性二甲胺基团。这种官能团的组合为这些分子在光可切换催化过程中的应用提供了可能性。通过预功能化的上半部和下半部的 Barton-Kellogg 耦合合成光响应中心核。使用 Buchwald-Hartwig 胺化和随后引入硫脲取代基的衍生化得到目标化合物。控制迈克尔加成反应中的催化活性(E )-3-溴-β-硝基苯乙烯和2,4-戊二酮是在双功能催化剂1的稳定-( E )和稳定-( Z )异构体的辐照下得到的。两种异构体在辐照到亚稳态后都表现出催化活性的降低,为系统提供了用作开/关催化光开关的潜力。
carbonylation reaction for the synthesis of fluoren‐9‐ones from 2‐halogenated biphenyls using phenyl formate as a carbon monoxide surrogate was achieved. The combined use of cesium carbonate and o‐anisic acid resulted in a remarkable rate enhancement, where the reaction was complete within 3 min in some cases. Mechanistic studies indicated that the turnover‐limiting step of the reaction was the C−H bond‐cleaving
Proton‐Gated Photoisomerization of Amino‐Substituted Dibenzofulvene Rotors
作者:Udaya K. Jayasundara、HyunJong Kim、Krishna P. Sahteli、Joseph I. Cline、Thomas W. Bell
DOI:10.1002/cphc.201601214
日期:2017.1.4
Derivatives of 9‐(2,2,2‐triphenylethylidene)‐fluorene (TEF) undergo E/Z photoisomerization and are candidates for light‐powered molecular actuators and switches. The 2‐substituted derivatives bearing an amino group (ATEF) or a dimethylamino group (DTEF) are weakly photoactive in the absence of acids, but protonation increases photoisomerization quantum yields by factors of 30–60. Such compounds may
Synergistic catalysis of Cu+/Cu0 for efficient and selective N-methylation of nitroarenes with para-formaldehyde
作者:Xiaosu Dong、Zhaozhan Wang、Youzhu Yuan、Yong Yang
DOI:10.1016/j.jcat.2019.06.022
日期:2019.7
species as the dominant sites on the surface during the reduction process. The resultant catalyst Cu/Al2O3 demonstrates high catalytic activity, selectivity and durability for the reductive N-methylation of easily available nitroarenes in a cost-efficient, environmentally friendly and cascade manner. A broad spectrum of nitroarenes could be efficiently N-methylated to their corresponding N,N-dimethyl amines
本文研究了一种廉价的非均相铜纳米颗粒催化剂,该催化剂是通过原位全位转化过程从CuAl层状双氢氧化物衍生而来的。具有均一尺寸的Cu纳米颗粒均匀地分散在无定形的Al 2 O 3上,具有很强的金属-载体相互作用。表征结果表明,在还原过程中,Cu 0和Cu +与Cu +物种同时形成为表面上的主要位点。所得催化剂Cu / Al 2 O 3对还原性N具有高催化活性,选择性和耐久性。以经济高效,环境友好和级联的方式对易得的硝基芳烃进行甲基化。可以将各种硝基芳烃有效地进行N-甲基化,使其与相应的N,N-二甲基胺形成各种官能团的良好相容性。该协议还适用于生物学和药学活性硝基分子的后期功能化。结构-功能关系表明,Cu 0和Cu +位点以协同方式显着提高了反应效率,其中Cu 0可以促进苯胺的H 2生成和N-甲基化,而Cu +的活性显着提高,并参与了硝基芳烃的选择性N-甲基化的整个过程。此外,该催化剂还显示出很强
Expedient Synthesis of <i>N</i>
-Methyl- and <i>N</i>
-Alkylamines by Reductive Amination using Reusable Cobalt Oxide Nanoparticles
作者:Thirusangumurugan Senthamarai、Kathiravan Murugesan、Kishore Natte、Narayana V. Kalevaru、Helfried Neumann、Paul C. J. Kamer、Rajenahally V. Jagadeesh
DOI:10.1002/cctc.201701617
日期:2018.3.21
the synthesis and functionalization of amines by using earth‐abundant metal‐based catalysts is of scientific interest. In this regard, herein we report an expedient reductive amination process for the selective synthesis of N‐methylated and N‐alkylated amines by using nitrogen‐doped, graphene‐activated nanoscale Co3O4‐based catalysts. Starting from inexpensive and easily accessible nitroarenes or amines
N-甲基和N-烷基胺代表重要的精细化学品和散装化学品,已广泛用于学术研究和工业生产中。值得注意的是,这些结构基序存在于大量生命科学分子中,并在调节其活动中起着至关重要的作用。因此,通过使用富含地球的金属基催化剂开发一种方便,经济高效的胺合成和官能化方法的研究具有科学意义。在这方面,我们在此报告了一种便捷的还原胺化工艺,该工艺通过使用氮掺杂的石墨烯活化的纳米级Co 3 O 4选择性合成N-甲基化和N-烷基化的胺。基于催化剂。从廉价且易于获得的硝基芳烃或胺和甲醛水溶液或存在甲酸的甲酸开始,这种经济高效的还原胺化方案可合成各种N-甲基和N-烷基胺,氨基酸衍生物和现有药物分子。
A New and Simple Synthesis of Fluoren-9-ones
作者:M. M. V. Ramana、P. V. Potnis
DOI:10.1055/s-1993-25908
日期:——
Ethyl cyclohexene-1-carboxylate (1) undergoes reaction with various aromatic substrates in presence of concentrated sulfuric acid to give cis-1,2,3, 4,4a,9a-hexahydrofluoren-9-ones 3a-f which on dehydrogenation afforded the corresponding fluoren-9-ones 4a-f in good yield. Fluorenones with an alkoxy group in the meta-orientation with respect to carbonyl group have also been prepared.