DDQ-mediated oxidation of sp3 C–H bond for the direct synthesis of vicinal tricarbonyl compounds
作者:Zheng-Lin Wang、Xing-Lan An、Li-Shi Ge、Jing-Hai Jin、Xiaoyan Luo、Wei-Ping Deng
DOI:10.1016/j.tet.2014.04.021
日期:2014.6
A facile and direct synthetic method was developed for the construction of vicinal tricarbonyl compounds (VTCs) in moderate to excellent yields (46-92%), by treating the readily available 1,3-dicarbonyl compounds with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The reaction pathway involves the DDQ-mediated oxidative activation of sp(3) C-H bond and subsequent coupling to TEMPO to form the key intermediate TEMPO-substrate adduct, which can be further converted to VTC products promoted by DDQ (C) 2014 Elsevier Ltd. All rights reserved.
DDQ-Mediated Oxidative Coupling: An Approach to 2,3-Dicyanofuran (Thiophene)
作者:Zheng-Lin Wang、Hong-Liang Li、Li-Shi Ge、Xing-Lan An、Zi-Gang Zhang、Xiaoyan Luo、John S. Fossey、Wei-Ping Deng
DOI:10.1021/jo4026034
日期:2014.2.7
A facile oxidative coupling of alpha-carbonyl radicals to 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) for the synthesis of 2,3-dicyanofurans and thiophenes starting from readily available beta-diketones, simple ketones, and beta-keto thioamides in up to 95% yield in one step was developed. Mechanistic investigations revealed that a radical process could be involved in this transformation, and a water promoted C-C bond cleavage pathway is proposed for the formation of 2,3-dicyanofurans and thiophenes.
Cinchona-Alkaloid-Derived NNP Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of β-Keto Ester
作者:Qian Xu、Wenchang Gou、Pinli Dai、Xuan Zhou、Jie Tian、Xin Meng、Yu Tian、Lin Zhang、Chun Li
DOI:10.1021/acs.joc.3c02032
日期:2024.2.2
The Ir-catalyzed asymmetrichydrogenation of β-ketoesters with Cinchona-alkaloid-derived NNP ligands has been developed. β-Hydroxy esters of opposite configuration were afforded smoothly with 91.5–99.1 and 81.6–99.3% ee, respectively, using NNP L2 and L7 derived from quinidine and quinine separately even on the gram scale. The protocol for the preparation of β-hydroxy esters of opposite configuration