Cross-Dehydrogenative Coupling of Heterocyclic Scaffolds with Unfunctionalized Aroyl Surrogates by Palladium(II) Catalyzed C(sp<sup>2</sup>)-H Aroylation through Organocatalytic Dioxygen Activation
作者:Bhavin V. Pipaliya、Asit K. Chakraborti
DOI:10.1021/acs.joc.7b00226
日期:2017.4.7
carbonyl group of aryl aldehyde and the aryl methane. However, the ease of availability of aryl methanes makes them the most attractive as an aroyl source. A time dependent selective mono- and bis-aroylation can be achieved. The 1,3-diarylpyrimidines exhibited regioselective aroylation of the 2-phenyl moiety irrespective of the absence or presence of any substitutent (electronwithdrawing or electron donating)
通过NHPI的双氧激活,在Pd(II)催化的C(sp 2)-H活化过程中,生物相关的杂环支架与芳基甲烷的芳基化反应进行了脱氢偶联。质谱和基于1 H NMR的动力学同位素效应研究表明,CH键的活化是决定速率的步骤。自由基清除实验表明存在自由基途径。在1等分试样的反应混合物的1 H NMR和用2-氨基硫代苯酚原位捕集揭示芳基甲烷的需氧氧化过程中醛的形成。该反应对于芳酰基源和包括苯并噻唑,苯并恶唑,吡啶,喹喔啉,嘧啶和偶氮芳烃的导向基团的不同变化具有广泛的范围。发现苄基亚甲基部分是芳酰基碳的来源,最优选苄基醚部分,其次是芳基醛和芳基甲烷的羰基。但是,芳基甲烷的易得性使其成为芳酰基源最具吸引力。可以实现时间依赖性的选择性单-和双-芳基化。1 3-二芳基嘧啶表现出2-苯基部分的区域选择性芳酰基化,而与3-苯基部分中是否存在任何取代基(吸电子或供电子)无关。对于不对称的偶氮芳烃,在带有取代基的苯基部分中发生选择性芳酰基化。
Ceric Ammonium Nitrate (CAN) Promoted Pd<sup>II</sup>-Catalyzed Substrate-Directed<i>o</i>-Benzoxylation and Decarboxylative<i>o</i>-Aroylation
作者:Sourav Kumar Santra、Arghya Banerjee、Nilufa Khatun、Bhisma K. Patel
DOI:10.1002/ejoc.201403367
日期:2015.1
Inexpensive cericammoniumnitrate (CAN) is an efficient oxidant for the Pd-catalyzed substrate-directed o-benzoxylation and decarboxylative o-aroylation processes. In the presence of CAN, the reaction of directing arenes with carboxylic acids resulted in o-benzoxylated products, whereas a decarboxylative o-aroylation occurred by using α-keto acids, which led to the formation of o-aroylation products
廉价的硝酸铈铵 (CAN) 是 Pd 催化的底物导向邻苯甲氧基化和脱羧邻芳酰化过程的有效氧化剂。在 CAN 存在下,定向芳烃与羧酸反应生成邻苯甲酰化产物,而使用 α-酮酸发生脱羧邻芳酰化,从而形成邻芳酰化产物。
Pd(<scp>ii</scp>)-catalysed o-aroylation of directing arenes using terminal aryl alkenes and alkynes
作者:Nilufa Khatun、Arghya Banerjee、Sourav K. Santra、Ahalya Behera、Bhisma K. Patel
DOI:10.1039/c4ra11014e
日期:——
A substrate-directed Pd-catalysed o-aroylation strategy has been demonstrated using new aroyl surrogates viz. terminal aryl alkenes and alkynes in the presence of TBHP. By a subtle change in catalyst from Cu to Pd, a differential selectivity is observed. While terminal aryl alkenes/alkynes in the presence of Cu/TBHP are reported to act as o-aryloxy (ArCOO–) sources, the use of Pd/TBHP installs an aroyl (ArCO–) group at the ortho position with respect to the directing arenes.
Palladium-Catalyzed<i>ortho</i>-Aroylation of 2-Arylbenzothiazoles and 2-Arylbenzoxazoles with Aldehydes
作者:Arghya Banerjee、Sourav Kumar Santra、Srimanta Guin、Saroj Kumar Rout、Bhisma K. Patel
DOI:10.1002/ejoc.201201503
日期:2013.3
protocol for the ortho-aroylation of 2-arylbenzothiazoles and 2-arylbenzoxazoles has been developed using aldehydes as the aroyl source. This Pd-catalyzed substrate-directed sp2-hybridized C–H bond functionalization occurs in the presence of the oxidant tert-butyl hydroperoxide. A variety of functional groups on the 2-arylbenzothiazoles, 2-arylbenzoxazoles, and aldehydes are tolerated under the reaction
An efficient protocol was developed for Pd-catalyzed direct C H bond acylation by cross-dehydrogenative-coupling of arylbenzothiazoles and benzylic alcohols using tert-butyl hydroperoxide (TBHP) as the oxidant. The acylation reactions exhibit good reactivities and excellent regioselectivity. (C) 2013 Elsevier Ltd. All rights reserved.