Xanthone undergoes regioselective substitution and nucleophically triggered ring opening to the corresponding ketone. Hydrazone of the latter oxidatively rearranges to ortho-diacylarenes, which, then, with hydrazine gives regioselectively substituted phthalazines. Molecular modeling analysis and H-1 NMR spectra indicate an intramolecular H-bonding engaging phenol OH and phthalazine N-3 atom.
Synthesis of Xanthones, Thioxanthones, and Acridones by the Coupling of Arynes and Substituted Benzoates
作者:Jian Zhao、Richard C. Larock
DOI:10.1021/jo0620718
日期:2007.1.1
The reaction of silylaryl triflates, CsF, and ortho-heteroatom-substituted benzoates affords a general and efficient way to prepare biologically interesting xanthones, thioxanthones, and acridones. This chemistry presumably proceeds by a tandem intermolecular nucleophilic coupling of the benzoate with an aryne and a subsequent intramolecular electrophilic cyclization.
FeCl<sub>3</sub>and ether mediated direct intramolecular acylation of esters and their application in efficient preparation of xanthone and chromone derivatives
作者:Neng Jiang、Su-Yi Li、Sai-Sai Xie、Hequan Yao、Hongbin Sun、Xiao-Bing Wang、Ling-Yi Kong
DOI:10.1039/c4ra10174j
日期:——
The direct intramolecular acylation of esters was developed by using the combined system of FeCl3 with Cl2CHOCH3. This unique cooperative system offered a new and efficient approach to biologically important xanthone and chromone derivatives with regioselectivity. Examples were reported, and control experiments were carried out to examine the effect of the benzyl esters and Cl2CHOCH3.
CBr<sub>4</sub> promoted intramolecular aerobic oxidative dehydrogenative arylation of aldehydes: application in the synthesis of xanthones and fluorenones
作者:Jing Tang、Shijun Zhao、Yuanyuan Wei、Zhengjun Quan、Congde Huo
DOI:10.1039/c7ob00080d
日期:——
promoted intramolecular aerobic oxidative dehydrogenative coupling reaction has been developed to provide a straightforward ring closure protocol for 2-aryloxybenzaldehydes to furnish xanthones. The reaction was performed under metal-, additive- and solvent-free conditions with good tolerance of functional groups. The present method is also applicable to the synthesis of fluorenones by using 2-arylbenzaldehydes
Oxidative [3+3] Annulation of Atropaldehyde Acetals with 1,3‐Bisnucleophiles: An Efficient Method of Constructing Six‐Membered Aromatic Rings, Including Salicylates and Carbazoles
作者:Yanlong Gu、Fengtian Wu、Jian Yang
DOI:10.1002/adsc.201800462
日期:2018.7.16
Alkyl acetoacetates, α‐(indol‐2‐yl)acetate, anilines, 1‐methyl‐1H‐pyrazol‐3‐amine, ethyl 5‐amino‐1H‐pyrazole‐3‐carboxylate, and 3‐amino‐1H‐indazole can all be used as 1,3‐bisnucleophiles in this type of transformation. The established reactions can very efficiently construct six‐membered aromatic rings, including salicylates and carbazoles. A four‐step method of synthesizing the anti‐inflammatory agent
Formation and Disproportionation of Xanthenols to Xanthenes and Xanthones and Their Use in Synthesis
作者:Zeyu Shi、Si Chen、Qiong Xiao、Dali Yin
DOI:10.1021/acs.joc.0c02694
日期:2021.2.19
A facile and versatile strategy employing TiCl4-mediated cyclization followed by a Cannizzaro reaction has been developed for the synthesis of various xanthene derivatives. The reaction proceeded smoothly to afford both xanthenes/xanthones or their sulfur derivatives and tolerated a wide range of electronically diverse substrates. Using this methodology, pranoprofen was synthesized in three steps in