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。
作者:Thomas M. Gøgsig、Dennis U. Nielsen、Anders T. Lindhardt、Troels Skrydstrup
DOI:10.1021/ol300837d
日期:2012.5.18
The direct carbonylativepalladiumcatalyzedsynthesis of monoprotected 1,3-ketoaldehydes is reported starting from aryl iodides applying near stoichiometric amounts of carbonmonoxide. Besides representing platforms for a variety of heterocyclic structures, these motives serve as viable precursors for the highly relevant aryl methyl ketones. The presented strategy can also be adapted for the facile
Iron Catalysis for Modular Pyrimidine Synthesis through β-Ammoniation/Cyclization of Saturated Carbonyl Compounds with Amidines
作者:Xue-Qiang Chu、Wen-Bin Cao、Xiao-Ping Xu、Shun-Jun Ji
DOI:10.1021/acs.joc.6b02767
日期:2017.1.20
method for the modular synthesis of various pyrimidine derivatives by means of the reactions of ketones, aldehydes, or esters with amidines in the presence of an in situ prepared recyclable iron(II)-complex was developed. This operationally simple reaction proceeded with broad functionalgroup tolerance in a regioselective manner via a remarkable unactivated β-C–H bond functionalization. Control experiments
Cu-Catalyzed [3 + 3] Annulation for the Synthesis of Pyrimidines via β-C(sp<sup>3</sup>)–H Functionalization of Saturated Ketones
作者:Jun-Long Zhan、Meng-Wei Wu、Fei Chen、Bing Han
DOI:10.1021/acs.joc.6b02181
日期:2016.12.2
A novel, efficient, and facile approach for the synthesis of structurally important pyrimidines has been successfully developed by Cu-catalyzed and 4-HO-TEMPO-mediated [3 + 3] annulation of commercially available amidines with saturated ketones. This method provides a new protocol for the synthesis of pyrimidines by a cascade reaction of oxidative dehydrogenation/annulation/oxidative aromatization
I<sub>2</sub>-Catalyzed Aerobic α,β-Dehydrogenation and Deamination of Tertiary Alkylamines: Highly Selective Synthesis of Polysubstituted Pyrimidines via Hidden Acyclic Enamines
β-dehydrogenation and deamination of tertiary alkylamines. This I2-catalyzed dehydrogenative multicomponent procedure utilizes simplealdehydes to trap the hidden enamine intermediates and suspend generation of azadienes from amidines, enabling the difunctionalization of a vicinal C(sp3)–H bond. These studies provide valuable possibilities for the introduction of aliphatic substituents and show how to