2,3‐Dichloro‐5,6‐Dicyano‐1,4‐Benzoquinone (DDQ)‐Mediated Tandem Oxidative Coupling/Intramolecular Annulation/Dehydro‐Aromatization for the Synthesis of Polysubstituted and Fused Pyridines
作者:Dongping Cheng、Zhiteng Deng、Xianhang Yan、Mingliang Wang、Xiaoliang Xu、Jizhong Yan
DOI:10.1002/adsc.201900956
日期:2019.11.5
A DDQ‐mediated tandem reaction of 1,3‐diarylpropenes and β‐enaminoesters/4‐aminocoumarins is disclosed. It involves oxidative coupling, intramolecular annulation and dehydro‐aromatization reaction, which provides an efficient and mild method for the synthesis of polysubstituted and fused pyridines under metal‐free conditions.
The first example of a Cu‐catalyzed and 4‐OH‐TEMPO mediated intermolecular [3+3] annulation of saturated ketones with β‐enamino esters is reported herein, which was successfully used for the synthesis of versatile nicotinates through sequential β‐C(sp3)‐H bond alkenylation, enamine‐carbonyl condensation and aromatization. This protocol tolerates a variety of functional groups, thereby providing a practical
Ce(IV) immobilized on halloysite nanotube–functionalized dendrimer (Ce(IV)–G2): A novel and efficient dendritic catalyst for the synthesis of pyrido[3,2‐
<i>c</i>
]coumarin derivatives
techniques. This catalyst was efficiently used for the one‐pot, single‐step multicomponent synthesis of pyrido[3,2‐c]coumarins from 4‐aminocoumarin, aldehydes, and aryl ketones. The efficiency and selectivity of this catalytic system were also evaluated for the synthesis of pyrido[3,2‐c]coumarins from terminal/internal alkynes instead of aryl ketones. In this respect, the regioselectivity of the products
在这项研究中,使用傅立叶变换红外光谱,元素分析,热重分析,场发射扫描电子显微镜,扫描电子显微镜-能量分散,设计,合成并表征了固定在埃洛石纳米管官能化树枝状聚合物上的新型稳定的Ce(IV)。 X射线光谱,透射电子显微镜,动态光散射,Brunauer-Emmett-Teller和感应耦合等离子体光学发射光谱技术。该催化剂可有效地用于从4-氨基香豆素,醛和芳基酮的单锅,一步一步多组分合成吡啶并[3,2- C ]香豆素。还评估了该催化体系的效率和选择性,以合成吡啶基[3,2- c]来自末端/内部炔烃的香豆素,而不是芳基酮。在这方面,通过X射线晶体学分析成功地确定了产物的区域选择性。所有这些反应都在只有0.28%(摩尔)的催化剂存在下无溶剂的条件下进行的最好的,并且吡啶并这种一锅合成的多组分[3,2- c ^ ]香豆素报道首次。还值得注意的是,用于合成多种吡啶并[3,2- c ]香豆素的一步和短的反
One pot synthesis of diarylpyrido[3,2-<i>c</i>]coumarins
作者:Shashi U. Pandya、Urvish R. Pandya、Bhanu R. Hirani、Dinker I. Brahmbhatt
DOI:10.1002/jhet.5570430343
日期:2006.5
Various diarylpyrido[3,2-c]coumarins 3a-l have been synthesized in one step by reacting 4-hydroxy coumarins 1a-d with α,β-unsaturated ketones 2a-c in the presence of ammonium acetate and acetic acid under Kroehnke's reaction conditions.
通过在Kroehnke反应下在乙酸铵和乙酸存在下使4-羟基香豆素1a-d与α,β-不饱和酮2a-c反应,一步合成了各种二芳基吡啶并[3,2 - c ]香豆素3a-1。情况。