Rhodium- and Iridium-Catalyzed Dehydrogenative Cyclization through Double C–H Bond Cleavages To Produce Fluorene Derivatives
摘要:
The rhodium-catalyzed cyclization of a series of 2,2-diarylalkanoic acids in the presence of copper acetate as an oxidant smoothly proceeded through double C-H bond cleavages and subsequent decarboxylation to produce the corresponding fluorene derivatives. The direct cyclization of triarylmethanols also took place efficiently by using an iridium catalyst in place of the rhodium, while the hydroxy function was still intact.
近年来,芳基卤化物和苄基卤化物与 CO2 的羧化取得了重大进展,成为使用化学计量量明确的金属物质的方便替代品。然而,这些过程中的大多数都需要使用自燃和空气敏感试剂,目前的方法主要限于有机卤化物。因此,非常希望发现一种温和的、操作简单的替代羧化反应,该羧化反应在广泛的底物范围内使用容易获得的偶联伙伴发生。在此,我们报告了一种新的协议,该协议涉及 CO2 协同活化的开发和惰性 C(sp(2))-O 和 C(sp(3))-O 键的相当具有挑战性的活化,这些键源自简单且廉价的酒精,这是该领域以前未被认识到的机会。这种前所未有的羧化事件的特点是其简单、温和的反应条件、显着的选择性模式以及使用对空气、水分不敏感且易于处理的镍预催化剂的优异化学选择性曲线。我们的结果使我们的方法成为一种强大的替代方案,实用性和新颖性,可以替代常用的有机卤化物作为羧化方案中的对应物。此外,这项研究首次表明,无痕导向基团允许在没有扩展
Visible‐Light‐Enabled Carboxylation of Benzyl Alcohol Derivatives with CO
<sub>2</sub>
Using a Palladium/Iridium Dual Catalyst
作者:Yushu Jin、Naoyuki Toriumi、Nobuharu Iwasawa
DOI:10.1002/cssc.202102095
日期:2022.2.8
Double trouble: A highly efficient visible-light-enabled carboxylation of benzyl alcohol derivatives using CO2 is achieved with a Pd/Ir dual catalyst. A variety of benzyl carboxylic acids and esters can be prepared from the corresponding benzyl alcohol derivatives with high efficiency. By changing the Pd catalyst, switchable site-selective carboxylation between benzylic C−O and aryl C−Cl moieties is
双重麻烦:使用Pd/Ir 双催化剂实现了使用 CO 2对苯甲醇衍生物进行高效可见光羧化。由相应的苄醇衍生物可以高效地制备多种苄基羧酸和酯。通过改变 Pd 催化剂,可以在苄基 C-O 和芳基 C-Cl 部分之间进行可切换的位点选择性羧化。
Ytterbium metal-promoted novel cross-coupling reaction between diaryl ketones and electrophiles
In the presence of Yb metal, diaryl ketones react nucleophilically with octan-2-one, acetonitrile, epoxides, and CO2 to give the corresponding unsymmetrical pinacols, α-hydroxy ketones, 1,3-diols, and α-hydroxy carboxylic acids, respectively.
The first ruthenium-catalyzed umpolung carboxylation of hydrazones with CO2 to generate important aryl acetic acids is reported. Besides aldehyde hydrazones, a variety of ketone hydrazones, which have not been successfully applied in previous umpolung reactions with other reactive electrophiles, also show high reactivity and selectivity under mild conditions. Moreover, this operationally simple protocol
报道了第一次钌催化腙与 CO 2的 umpolung 羧化生成重要的芳基乙酸。除醛腙外,多种酮腙在与其他反应性亲电试剂的超微球反应中尚未成功应用,在温和条件下也表现出高反应性和选择性。此外,这种操作简单的协议具有良好的官能团耐受性,易于扩展,并提供了重要结构的简单推导,包括生物活性联苯乙酸和阿地芬。计算研究表明,这种 umpolung 反应通过生成 Ru-nitrenoid 然后与 CO 2协同 [4 + 2] 环加成反应进行。
Photoredox-Neutral Deoxygenative Carboxylation of Acylated Alcohols with Tetrabutylammonium Oxalate
Herein, a photoredox-neutral strategy for carboxylation of acylated alcohols via C(sp3)–O bond activation and cleavage with tetrabutylammonium oxalate (TBAO) as the carbonyl source and reductant as well as the promoter is described. Neither a pre-established CO2 atmosphere nor external electron donors are required as the TBAO is crucial for the transformation. Various primary, secondary, and tertiary