<i>peri</i>
‐Xanthenoxanthene (PXX): a Versatile Organic Photocatalyst in Organic Synthesis
作者:Cristofer Pezzetta、Andrea Folli、Oliwia Matuszewska、Damien Murphy、Robert W. M. Davidson、Davide Bonifazi
DOI:10.1002/adsc.202100030
日期:2021.10.19
to be accessible: the β-arylation of cyclic ketones is successful when using a secondary amine as organocatalyst, while cross-coupling reactions of aryl halides with amines and thiols are obtained when using a Ni co-catalyst. Application to the efficient two-step synthesis of the expensive fluoro-tetrahydro-1H-pyrido[4,3-b]indole, a crucial synthetic intermediate for the investigational drug setipiprant
近年来,光催化剂的不断发展,以满足对光氧化还原催化中光物理和氧化还原性能日益增长的需求,设计了复杂的结构或替代策略来获得高度还原或氧化系统。我们在此报告了使用peri- xanthenoxanthene (PXX),一种简单且廉价的染料,作为一种有效的光催化剂。其高度还原的激发态可激活多种底物,从而引发有用的自由基反应。最初证明了基准转换,例如通过有机卤化物的光还原产生的有机自由基添加到自由基陷阱。还显示可以使用更复杂的双催化歧管:β当使用仲胺作为有机催化剂时,环酮的芳基化是成功的,而当使用 Ni 助催化剂时,芳基卤化物与胺和硫醇的交叉偶联反应是成功的。昂贵的氟-四氢-1 H-吡啶并[4,3- b ]吲哚的高效两步合成应用也已得到证实,该吲哚是研究药物塞替吡仑的关键合成中间体。
Nickel-Catalyzed Ring-Opening C–O Functionalization of <i>peri</i>-Xanthenoxanthenes for 8-Substituted Binaphthol Synthesis
Herein, we disclose the Ni-catalyzed ring-opening C–O functionalization of peri-xanthenoxanthenes using Grignard reagents that forms 8-monofunctionalized binaphthols. 1,2-Bis(dicyclohexylphosphino)ethane was the best ligand for alkylations and ICy for arylation. After mechanistic investigations, we assumed that the reaction proceeds via C–O reduction and subsequent C–O functionalization. To verify
Three kinds of charge-transfer (CT) complexes of PXX (PXX = 6, 12-dioxaanthanthrene) have been newly prepared and structurally characterized. In the 1 : 2 CT complex with TNP (TNP = 2,4,6-trinitrophenol), PXX is practically neutral. In the semiconducting partially oxidized salt with I3, the PXX molecules form a trimer and each PXX is formally oxidized by e/3. In the 3 : 2 salt with [Ni(mnt)2]- (mnt = maleonitriledithiolate), the PXX molecules again form a trimer unit and each PXX is formally oxidized by 2e/3. Together with the structural data obtained from the PXX single component crystal, the molecular geometry change by the formal charge on PXX has been examined. A noticeable change has been found in the aromatic ring framework, which is consistent with the distribution of the HOMO coefficients obtained from the extended Hückel calculation.