Merging gold catalysis, organocatalytic oxidation, and Lewis acid catalysis for chemodivergent synthesis of functionalized oxazoles from N-propargylamides
作者:Shaoyu Mai、Changqing Rao、Ming Chen、Jihu Su、Jiangfeng Du、Qiuling Song
DOI:10.1039/c7cc05746f
日期:——
Novel catalytic systems consisting of cationicgold complexes, N-hydroxyphthalimide (NHPI), and transition-metal-based Lewis acids have been developed for the one-pot synthesis of functionalized oxazoles from N-propargylamides with excellent functional group tolerance. These transformations demonstrated the excellent compatibility of homogeneous goldcatalysis with organocatalytic oxidative carbon–nitrogen
A Simple One-Pot Synthesis of 2-Aryl-5-alkyl-Substituted Oxazoles by Cs2CO3-Mediated Reactions of Aromatic Primary Amides with 2,3-Dibromopropene
作者:Jayanta Ray、Nasima Yasmin
DOI:10.1055/s-0029-1217995
日期:2009.10
A simple and efficient method for the synthesis of 2-aryl-5-alkyl-substituted oxazoles has been developed. A series of 2,5-disubstituted oxazoles were synthesized in a single step by Cs2CO3-mediated reactions of aromatic primary amides with 2,3-dibromopropene.
[reaction: see text] 2,5-Disubstituted oxazoles have been prepared through the reaction of N-propargylamides with aryl iodides in the presence of Pd(2)(dba)(3), tri(2-furyl)phosphine, and NaO(t)()Bu. The reaction appears to proceed through a palladium-catalyzed coupling step followed by the in situ cyclization of the resultant coupling product.
compounds have been studied. This investigation has led to the development of a mild, economic, and effective method for the synthesis of functionalized 4H-1,3-oxazines, 4H-1,3-thiazines, 4,5-dihydrothiazoles, and α-substituted enones. The structure of the propargylicsubstrate and the nature of electrophile influence both the outcome and regioselectivity of processes.
Palladium(II)-Catalyzed Directed <i>anti-</i>Hydrochlorination of Unactivated Alkynes with HCl
作者:Joseph Derosa、Annabelle L. Cantu、Mark N. Boulous、Miriam L. O’Duill、Joshua L. Turnbull、Zhen Liu、Daizy M. De La Torre、Keary M. Engle
DOI:10.1021/jacs.7b00892
日期:2017.4.12
A regioselective anti-hydrochlorination of unactivated alkynes is reported. The reaction utilizes in situ generated HCl as the source of both the Cl- and H+ and is catalyzed by palladium(II) acetate, with loadings as low as 25 ppm. Removable picolinamide and 8-aminoquinoline bidentate directing groups are used to control the regioselectivity of the chloropalladation step and stabilize the resulting
报道了未活化炔烃的区域选择性抗氢氯化作用。该反应利用原位生成的 HCl 作为 Cl- 和 H+ 的来源,并由乙酸钯 (II) 催化,负载量低至 25 ppm。可去除的吡啶甲酰胺和 8-氨基喹啉二齿导向基团用于控制氯钯化步骤的区域选择性,并稳定所得的链烯基钯 (II) 中间体,用于随后的原脱钯反应。该方法提供了以优异的产率和高区域选择性获得广泛的取代链烯基氯的途径。这种转化的产物通过 Stille 偶联成功衍生为多种三取代烯烃产物。进行了反应进程动力学分析,揭示了该催化过程的可能机制。