- One-step preparation of xanthones via Pd-catalyzed annulation of 1,2-dibromoarenes and salicylaldehydes
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A one-step preparation of xanthones via Pd-catalyzed annulation of 1,2-dibromoarenes and salicylaldehydes was developed.
- Wang, Sizhuo,Xie, Kai,Tan, Ze,An, Xiangyu,Zhou, Xingjian,Guo, Can-Cheng,Peng, Zhihong
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- The involvement of xanthone and (E)-cinnamoyl chromophores for the design and synthesis of novel sunscreening agents
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Excessive UV exposure contributes to several pathological conditions like skin burns, er-ythema, premature skin aging, photodermatoses, immunosuppression, and skin carcinogenesis. Effective protection from UV radiation may be achieved with the use of sunscreens containing UV filters. Currently used UV filters are characterized by some limitations including systemic absorp-tion, endocrine disruption, skin allergy induction, and cytotoxicity. In the research centers all over the world new molecules are developed to improve the safety, photostability, solubility, and absorption profile of new derivatives. In our study, we designed and synthesized seventeen novel molecules by combining in the structures two chromophores: xanthone and (E)-cinnamoyl moiety. The ultraviolet spectroscopic properties of the tested compounds were confirmed in chloroform solutions. They acted as UVB or UVA/UVB absorbers. The most promising compound 9 (6-meth-oxy-9-oxo-9H-xanthen-2-yl)methyl (E)-3-(2,4-dimethoxyphenyl)acrylate) absorbed UV radiation in the range 290–369 nm. Its photoprotective activity and functional photostability were further evaluated after wet milling and incorporation in the cream base. This tested formulation with compound 9 possessed very beneficial UV protection parameters (SPFin vitro of 19.69 ± 0.46 and UVA PF of 12.64 ± 0.32) which were similar as broad-spectrum UV filter tris-biphenyl triazine. Additionally, compound 9 was characterized by high values of critical wavelength (381 nm) and UVA/UVB ratio (0.830) thus it was a good candidate for broad-spectrum UV filter and it might protect skin against UVA-induced photoaging. Compound 9 were also shown to be photostable, non-cytotoxic at con-centrations up to 50 μM when tested on five cell lines, and non-mutagenic in Ames test. It also possessed no estrogenic activity, according to the results of MCF-7 breast cancer model. Addition-ally, its favorable lipophilicity (miLogP = 5.62) does not predispose it to penetrate across the skin after topical application.
- Popió?, Justyna,Gunia-Krzy?ak, Agnieszka,S?oczyńska, Karolina,Koczurkiewicz-Adamczyk, Paulina,Piska, Kamil,Wójcik-Pszczo?a, Katarzyna,?elaszczyk, Dorota,Krupa, Anna,?mudzki, Pawe?,Marona, Henryk,P?kala, El?bieta
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- A Green Nanopalladium-Supported Catalyst for the Microwave-Assisted Direct Synthesis of Xanthones
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We report an efficient, selective, rapid and eco-friendly protocol for the one-step synthesis of a small xanthone library via an intermolecular catalytic coupling from readily available salicylaldehydes and 1,2-dihaloarenes under ligand-free conditions. To achieve this advantageous direct annulation, we used a novel recoverable palladium nanocatalyst supported on a green biochar under microwave irradiation. Unlike other existing palladium-based approaches, our synthetic strategy showed a greater operational simplicity, drastic reduction in reaction times, and an excellent tolerance to diverse functional groups. The reaction proceeds in very good yields and with high regioselectivity. The novel heterogeneous catalyst can be recycled and reused up to four times without significant loss of activity.
- Diez, Alejandra S.,Gerbino, Darío C.,Mendioroz, Pamela,Steingruber, H. Sebastián
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supporting information
p. 619 - 628
(2020/02/13)
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- Concise synthesis of xanthones by the tandem etherification—Acylation of diaryliodonium salts with salicylates
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An efficient synthetic method for multi-substituted xanthones was developed. The reaction of diaryliodonium salts and salicylates was employed for the preparation of the xanthones. This method proceeded through an intermolecular etherification-acylation t
- Liu, Gaoxiaozheng,Wu, Chao,Chen, Bifeng,He, Ru,Chen, Chao
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p. 985 - 988
(2018/04/05)
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- CBr4 promoted intramolecular aerobic oxidative dehydrogenative arylation of aldehydes: application in the synthesis of xanthones and fluorenones
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A simple and practical carbon tetrabromide 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 as substrates. Preliminary studies of the reaction mechanism indicated that the reaction may proceed through a radical pathway.
- Tang, Jing,Zhao, Shijun,Wei, Yuanyuan,Quan, Zhengjun,Huo, Congde
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supporting information
p. 1589 - 1592
(2017/02/23)
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- Selective Preparation of Xanthones from 2-Bromofluorobenzenes and Salicylaldehydes via Palladium-Catalyzed Acylation-SNAr Approach
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A regioselective pathway for the preparation of xanthones from 2-bromofluorobenzenes and salicylaldehydes has been developed. The reaction proceeded through palladium-catalyzed acylation-SNAr sequence. Good to moderate yields of the desired xanthones were prepared in one step. Based on the results of control experiments, a possible reaction mechanism has been proposed.
- Shen, Chaoren,Wu, Xiao-Feng
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supporting information
p. 1269 - 1273
(2016/05/10)
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- Synthesis of xanthones through the palladium-catalyzed carbonylation/C-H activation sequence
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A series of xanthones with the dibenzo-γ-pyrone framework were synthesized through the palladium-catalyzed carbonylation/C-H activation sequence from the ortho diazonium salts of diaryl ethers in moderate to excellent yields. After screening the reaction condition, the optimal condition was 5 mol % tetrakis (triphenylphosphine) palladium (0) as the catalyst, potassium carbonate as the base, and toluene as the solvent in the presence of catalytic amount of tetrabutyl ammonium bromide under carbon monoxide atmosphere.
- Xu, Yingmeng,Zhou, Jing,Zhang, Congcong,Chen, Ke,Zhang, Tao,Du, Zhenting
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supporting information
p. 6432 - 6434
(2014/12/10)
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- FeCl3 and ether mediated direct intramolecular acylation of esters and their application in efficient preparation of xanthone and chromone derivatives
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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.
- Jiang, Neng,Li, Su-Yi,Xie, Sai-Sai,Yao, Hequan,Sun, Hongbin,Wang, Xiao-Bing,Kong, Ling-Yi
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supporting information
p. 63632 - 63641
(2015/02/19)
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- One-step synthesis of xanthones catalyzed by a highly efficient copper-based magnetically recoverable nanocatalyst
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A versatile and highly efficient strategy to construct a xanthone skeleton via a ligand-free intermolecular catalytic coupling of 2-substituted benzaldehydes and a wide range of phenols has been developed. For this purpose, a novel and magnetically recoverable catalyst consisting of copper nanoparticles on nanosized silica coated maghemite is presented. The reaction proceeds smoothly with easy recovery and reuse of the catalyst. The methodology is compatible with various functional groups and provides an attractive protocol for the generation of a small library of xanthones in very good yield.
- Menendez, Cintia A.,Nador, Fabiana,Radivoy, Gabriel,Gerbino, Dario C.
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supporting information
p. 2846 - 2849
(2014/06/23)
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- Metal-free oxidative coupling: Xanthone formation via direct annulation of 2-aryloxybenzaldehyde using tetrabutylammonium bromide as a promoter in aqueous medium
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A metal-free intramolecular annulation of 2-aryloxybenzaldehydes to xanthones is disclosed, which proceeds through the direct oxidative coupling of an aldehyde C-H bond and aromatic C-H bonds using tetrabutylammonium bromide (TBAB) as a promoter in aqueous medium. This strategy works smoothly in the presence of both electron-donating and electron-withdrawing groups, and displays good tolerance towards catalytically reactive substituents, thus promising further functionalizations of xanthone products.
- Rao, Honghua,Ma, Xinyi,Liu, Qianzi,Li, Zhongfeng,Cao, Shengli,Li, Chao-Jun
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supporting information
p. 2191 - 2196
(2013/10/01)
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- Xanthones in heterocyclic synthesis. An efficient route for the synthesis of C-3 o-Hydroxyaryl substituted 1, 2-benzisoxazoles and their N-oxides, potential scaffolds for angiotensin(II) antagonist hybrid peptides
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Regioselective substitution of xanthone and its nucleophilic cleavage allow the synthesis of C-3 ohydroxyaryl substituted 1, 2-benzisoxazoles or their V-oxides by cyclodehydration or oxidative cyclization of their corresponding ketoxime precursors, respectively. Molecular modeling analysis and 1H NMR spectra indicate an intramolecular H-bonding engaging phenol OH and the isoxazole ring N atom. The Japan Institute of Heterocyclic Chemistry.
- Gardikis, Yiannis,Tsoungas, Petros G.,Potamitis, Constantinos,Zervou, Maria,Cordopatis, Paul
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scheme or table
p. 1077 - 1091
(2011/06/19)
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- Xanthone in synthesis: a reactivity profile via directed lithiation of its dimethyl ketal
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Xanthone, as its dimethyl ketal, undergoes functionalization with a synthetically useful degree of regioselectivity using a lithiation protocol. The core structure is regenerated during the work-up. Monosubstitution at C-4 or C-1 and disubstitution at C-4
- Odrowaz-Sypniewski, Michal R.,Tsoungas, Petros G.,Varvounis, George,Cordopatis, Paul
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body text
p. 5981 - 5983
(2010/02/28)
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- Reaction of benzyne with salicylaldehydes: General synthesis of xanthenes, xanthones, and xanthols
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The reaction of salicylaldehydes with benzyne prepared from o-trimethylsilyphenyl triflate and CsF gave xanthenes and xanthones. When the reaction was carried out under basic conditions, 9-hydroxyxanthenes (xanthols) were obtained in good yields.
- Okuma, Kentaro,Nojima, Akiko,Matsunaga, Nahoko,Shioji, Kosei
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supporting information; experimental part
p. 169 - 171
(2009/06/20)
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- Photolabile protecting groups based on the singlet state photodecarboxylation of xanthone acetic acid
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A new photolabile protecting group (PPG) for carboxylic acids and amineshas been developed based on the rapid singlet state photodecarboxylatio n of xanthone acetic acids with several features that are superior to many other systems. We demonstrate that t
- Blake, Jessie A.,Lukeman, Matthew,Scaiano, Juan C.
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supporting information; experimental part
p. 4127 - 4135
(2009/09/04)
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- Carbanionic friedel-crafts equivalents. Regioselective directed Ortho and remote metalation-C-N cross coupling routes to acridones and dibenzo[b,f]azepinones
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(Chemical Equation Presented) Carbanion-mediated general regioselective routes to acridones 4 (Table 2) and dibenzo[b,f]azepinones 20 (Table 4) are described. Buchwald-Hartwig C-N cross coupling of o-halo benzamides 1 with anilines 2 or 16, followed by simple N-methylation, dependably provides N-methyl diarylamines 3 (Table 1) and 18 (Table 3). Upon treatment with LDA, 3 and 18 are converted into acridones 4 and dibenzo[b,f]azepinones 20, respectively, in good to excellent yields with regioselectivity which depends upon the presence or absence of directed metalation groups (DMGs). Brief investigations as follows are described: the synthesis of desmethyl acridone 15 (Scheme 4), an attempt to effect a double-directed remote metalation sequence which leads only to a monocyclization product 13 (Scheme 3), and an analogous but nonregioselective route to a xanthone 22 and dibenzo[b,f]oxepinone 24 (Scheme 5). DFT calculations reveal low energy conformations for compounds 18b and 23 which account for product formation and indicate that the cyclization reactions are under kinetic control.
- MacNeil, Stephen L.,Gray, Matthew,Gusev, Dmitry G.,Briggs, Laura E.,Snieckus, Victor
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supporting information; experimental part
p. 9710 - 9719
(2009/04/07)
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- Photodecarboxylation of xanthone acetic acids: C-C bond heterolysis from the singlet excited state
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Irradiation of 2- and 4-xanthone acetic acid in aqueous buffer (pH 7.4) leads to efficient (Φ = 0.67 and 0.64, respectively) photodecarboxylation to give the corresponding methyl products, consistent with an intermediate benzylic carbanion. Fluorescence a
- Blake, Jessie A.,Gagnon, Eric,Lukeman, Matthew,Scaiano
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p. 1057 - 1060
(2007/10/03)
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- Substituted xanthones as antimycobacterial agents*, part 1: Synthesis and assignment of 1H/13C NMR chemical shifts
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A series of substituted xanthones was synthesized in order to prove the hypothesis that electron-withdrawing substituents enhance the antimycobacterial activity of these compounds, which is described by means of a QSAR equation with 13C NMR che
- Pickert, Martina,Frahm, August Wilhelm
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p. 177 - 192
(2007/10/03)
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- Intramolecular Anionic Friedel-Crafts Equivalents. A General Regiospecific Route to Substituted and Naturally Occurring Xanthen-9-ones
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An LDA-induced regiospecific and general conversion of diaryl ether 2-carboxamides 4 into substituted xanthones 5, including natural products, 2-hydroxy-1-methoxyxanthone (8) and 6-deoxyjacareubin (14), is described.
- Familoni,Ionica, Ileana,Bower, Justin F.,Snieckus, Victor
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p. 1081 - 1083
(2007/10/03)
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- Synthesis of N-(9H-xanthen-9-yl)aminoalkanamide and N-(9H-thioxanthen-9-yl)aminoalkanamide derivatives and their in vitro evaluation as potential intercalators and antitumor drugs
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A series of new N-(9H-xanthen-9-yl)aminoalkanamide and N-(9H-thioxanthen-9-yl)aminoalkanamide derivatives was synthesized and evaluated as potential intercalators by measuring their DNA binding affinity. They were also tested for cytotoxic activity against L1210. The results suggest that the cytotoxicity of these molecules was not due to an intercalating mechanism.
- Filippatos,Papadaki-Valiraki,Todoulou,Jacquemin-Sablon
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- Synthesis and antitumor activity of some new 2-chloroethylnitrosoureas
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The synthesis of a series of N-(2-chloroethyl)-N'-(9H-xanthen-9-yl)-N-nitrosoureas and N-(2-chloroethyl)-N'-(9H-thioxanthen-9-yl)-N-nitrosoureas is described. The title compounds were evaluated against NSCLCN6 L16 bronchial epidermoid carcinoma in vitro and some of them were found to be active. N-(2-chloroethyl)-N'-(2-methoxy-9H-xanthen-9-yl)-N-nitrosourea (8e) was active against leukemia P388 tumor system in mice.
- Filippatos,Papadaki-Valiraki,Roussakis,Verbist
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p. 451 - 456
(2007/10/02)
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