4819-85-6Relevant academic research and scientific papers
Copper-catalyzed aerobic asymmetric cross-dehydrogenative coupling of C(sp3)-H bonds driven by visible light
Gong, Lei,Li, Yanjun,Lin, Yu-Mei,Yu, Ying,Zhou, Kexu
, p. 4597 - 4603 (2020/08/10)
Asymmetric cross-dehydrogenative coupling (CDC) of C(sp3)-H bonds shows great potential for rapid and stereoselective construction of C-C bonds and use of molecular oxygen as the oxidant for such transformations is appealing in the context of green synthetic methodologies. However, the poor reactivity of oxygen at the ground state and the challenges in controlling the stereochemistry make it extremely difficult to access highly enantioselective aerobic CDC reactions of C(sp3)-H precursors. Herein we report our effort towards this goal via copper-based asymmetric photocatalysis. A chiral-copper catalyst initiates the visible-light-driven oxidative CDC reaction by molecular oxygen, and governs the stereochemistry. In this way, a diastereo- and enantioselective cross-dehydrogenative coupling between carbonyl compounds and xanthene derivatives has been achieved. This work provides an economic and manageable approach to stereoselective C-C bond formation, and demonstrates a potential application of chiral copper catalysts in difficult asymmetric photochemical reactions.
Cascade nucleophilic addition-cyclic Michael addition of arynes and phenols/anilines bearing ortho α,β-unsaturated groups: Facile synthesis of 9-functionalized xanthenes/acridines
Huang, Xian,Zhang, Tiexin
supporting information; experimental part, p. 506 - 509 (2010/03/30)
(Chemical Equation Presented) A facile synthesis of xanthenes and acridines based on a cascade nucleophilic addition-cyclic Michael addition process of arynes and phenols/anilines substituted with α,β-unsaturated groups at the ortho positions is described
Manganese(III)-Mediated Carbon-Carbon Bond Formation in the Reaction of Xanthenes with Active Methylene Compounds
Nishino, Hiroshi,Kamachi, Hironori,Baba, Harumi,Kurosawa, Kazu
, p. 3551 - 3557 (2007/10/02)
Oxidation of xanthenes with manganese(III) acetate in the presence of active methylene compounds such as 1,3-dicarbonyl compounds, malononitrile derivatives, acetone, and nitromethane selectively gives 9-substituted xanthene derivatives in good yields.A similar oxidation of thioxanthene also yields 2-(9-thioxanthenyl)-1,3-dicarbonyl compounds in 57-91 percent yields.The obtained 2-(9-xanthenyl)-1,3-dicarbonyl compounds are readily converted to 2-(9-xanthenylidene)-1,3-dicarbonyl derivatives using manganese(III) complexes or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.The mechanisms for the formation of 9-substituted xanthenes are discussed on the basis of the reaction intermediates, the electron-donating substituent effect on the xanthene ring system, effect of additives, and comparison with a reaction of radical-trapping reagents.
