Gold Redox Catalysis through Base‐Initiated Diazonium Decomposition toward Alkene, Alkyne, and Allene Activation
作者:Boliang Dong、Haihui Peng、Stephen E. Motika、Xiaodong Shi
DOI:10.1002/chem.201701970
日期:2017.8.16
The discovery of photoassisted diazonium activation toward gold(I) oxidation greatly extended the scope of goldredoxcatalysis by avoiding the use of a strongoxidant. Some practical issues that limit the application of this new type of chemistry are the relative low efficiency (long reaction time and low conversion) and the strict reaction condition control that is necessary (degassing and inert
通过避免使用强氧化剂,光辅助重氮盐向金(I)氧化活化的发现大大扩展了金氧化还原催化的范围。限制这种新型化学方法应用的一些实际问题是相对较低的效率(较长的反应时间和较低的转化率)和必须进行严格的反应条件控制(脱气和惰性反应环境)。在本文中,通过路易斯碱诱导的重氮活化已经开发出另一种无光条件。通过这种方法,将不活泼的Au I催化剂与Na 2 CO 3和重氮盐结合使用以生产Au III中间的。实现了对各种基质(包括炔烃,烯烃和丙二烯)的有效活化,然后快速进行了Au III还原消除,从而得到了具有良好收率或优异收率的C-C偶联产物。相对于以前报道的光活化方法,我们的方法通过更快的反应速率和更宽的反应范围提供了更高的效率和多功能性。在光引发条件下(<5%收率)不能活化的具有挑战性的底物,例如富电子/中性亚勒烯,可以被活化,随后以良好或优异的产率产生所需的偶联产物。
Enantioselective oxysulfenylation and oxyselenenylation of olefins catalyzed by chiral Brønsted acids
作者:Huan Guan、Haining Wang、Deshun Huang、Yian Shi
DOI:10.1016/j.tet.2012.01.006
日期:2012.3
This paper describes Brønsted acid catalyzed enantioselective oxysulfenylation and oxyselenenylation of olefins. Enantiomerically enriched tetrahydrofurans are formed with up to 63% ee with dibenzoyl-d-tartaric acid and its derivatives as catalyst. Chiral β-carboxyl sulfides and selenides have also been obtained with up to 50% and 84% ee, respectively, via enantioselective desymmetrization of thiiranium
O–H hydrogen bonding promotes H-atom transfer from α C–H bonds for C-alkylation of alcohols
作者:Jenna L. Jeffrey、Jack A. Terrett、David W. C. MacMillan
DOI:10.1126/science.aac8555
日期:2015.9.25
alcohols is selectively induced by using an H-bonding catalyst to bind the hydroxyl group of the alcohol. The adjacent C-H bonds now become susceptible to a reaction accelerated by another pair of catalysts. In combination, the trio of catalysts promotes C-C bond formation at the alcohol C within an array of competing sites. Science, this issue p. 1532 Hydrogen bonding confers siteselectivity in a carbon-carbon
三重奏有助于激活醇中的 CH 键酶可以通过位置良好的 H 键激活分子的特定部分来加速化学反应。杰弗里等人。在合成环境中展示氢键的力量。在这里,醇的 C 中心的反应性是通过使用 H 键催化剂来结合醇的羟基而选择性地诱导的。相邻的 CH 键现在变得容易受到另一对催化剂加速的反应的影响。组合起来,这三种催化剂促进了在一系列竞争位点内的醇 C 处形成 CC 键。科学,这个问题 p。1532 氢键在醇和烯烃之间的碳-碳键形成反应中赋予位点选择性。在存在多个潜在的氢原子供体和受体的情况下,从有机分子转移氢原子的效率和选择性通常难以控制。在这里,我们描述了一种催化活化模式的机理评估,该模式通过氢原子转移机制实现了醇与丙烯酸甲酯的高选择性光氧化还原 α-烷基化/内酯化。我们的研究表明,在烯丙基、苄基、α-C=O 和 α-醚 C-H 键存在的情况下,四正丁基磷酸铵在提高醇中 α C-H 键的选择性方面具有特
Ruthenium and Iron‐Catalysed Decarboxylative
<i>N</i>
‐alkylation of Cyclic α‐Amino Acids with Alcohols: Sustainable Routes to Pyrrolidine and Piperidine Derivatives
A modular and waste‐free strategy for constructing N‐substituted cyclic amines via decarboxylative N‐alkylation of α‐amino acids employing ruthenium‐ and iron‐based catalysts is presented. The reported method allows the synthesis of a wide range of five‐ and six‐membered N‐alkylated heterocycles in moderate‐to‐excellent yields starting from predominantly proline and a broad range of benzyl alcohols