我们报道了金鸡纳生物碱催化苯硫酚加成快速相互转化的芳基萘醌,在还原甲基化后产生稳定的联芳基阻转异构体。对一系列苯硫酚和萘醌底物进行了评估,我们观察到高达 98.5:1.5 的选择性。对醌氧化还原性质的控制使我们能够研究底物每种氧化态的立体化学稳定性。所得的对映体富集产物还可以通过 S N Ar 类反应序列继续进行,以获得具有优异对映体保留的稳定衍生物。
NHC-Catalyzed Dual Stetter Reaction: A Mild Cascade Annulation for the Syntheses of Naphthoquinones, Isoflavanones, and Sugar-Based Chiral Analogues
作者:Rajendra N. Mitra、Krishanu Show、Debabrata Barman、Satinath Sarkar、Dilip K. Maiti
DOI:10.1021/acs.joc.8b01503
日期:2019.1.4
successfully employed for the construction of opticallypure sugar-based naphthoquinones and dihydroisoflavanones. Herein, NHC is found as a unique and powerful organocatalyst to construct homoatomic C–C cross-coupling, heteroatomic O–C bond formation, and cascade cyclization utilizing NO2 as a leaving group at ambient temperature. A mechanistic pathway of the new metal-free catalysis is predicted on
Comprehensive evaluation of antioxidant effects of Japanese Kampo medicines led to identification of Tsudosan formulation as a potent antioxidant agent
Insurance Drug List, using in vitro radical scavenging assays, including the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity assay, the superoxide anion scavenging activity assay, and the oxygen radical absorption capacity assay. Three of the formulations tested, namely, Tsudosan, Daisaikoto, and Masiningan, showed the most potent in vitro antioxidant activities and were selected for further
Hauser-Kraus Annulation of Phthalides with Nitroalkenes for the Synthesis of Fused and Spiro Heterocycles
作者:Tarun Kumar、Nishikant Satam、Irishi N. N. Namboothiri
DOI:10.1002/ejoc.201600390
日期:2016.7
Hauser–Kraus annulation of sulfonylphthalides with simple conjugated nitroalkenes follows the expected pathway to furnish naphthoquinones in moderate yields. However, a strategic variation of this reaction by employing nitroalkenes bearing an additional nucleophilic site results in [4+4] annulation leading to complex fused and spiro heterocycles in high yields with high selectivity through a cascade
New and Efficient Protocol for Arylation of Quinones
作者:Oleg Demchuk、K. Pietrusiewicz
DOI:10.1055/s-0028-1088118
日期:2009.4
A practical rhodium-mediated arylation of 1,4-quinones has been developed. The corresponding 2-aryl-1,4-quinones were obtained with excellent selectivity and high yields under convenient aerobic reaction conditions.