3117-02-0Relevant articles and documents
Helical-Shaped Bis-1,4-benzoxathiines through an Inverse-Electron-Demand Hetero-Diels–Alder Reaction of ortho-Thioquinones
Viglianisi, Caterina,Menichetti, Stefano,Piantini, Sara,Tofani, Lorenzo
, p. 5386 - 5392 (2016)
The reaction of transient ortho-thioquinones, which act as electron-poor dienes, with properly designed bis-dienophiles leads to the formation of helical-shaped bis-benzoxathiine cycloadducts with complete control of the regiochemistry and the relative stereochemistry. Bis-benzoxathiines were the result of two consecutive inverse-electron-demand cycloaddition processes with stereospecific approach of the diene anti to the bis-dienophile. The helical-shaped structure of the final products was demonstrated spectroscopically and confirmed by single-crystal X-ray analysis.
Polyoxometalate-based supramolecular porous frameworks with dual-active centers towards highly efficient synthesis of functionalized: P -benzoquinones
An, Haiyan,Chang, Shenzhen,Chen, Yanhong,Huang, Yaohui,Luo, Huiyun,Zhu, Qingshan
, p. 8591 - 8603 (2021/11/17)
Selective oxidation of substituted phenols is an ideal method for preparing functionalized p-benzoquinones (p-BQs), which serve as versatile raw materials for the synthesis of a variety of biologically active compounds. Herein, two new polyoxometalate-based supramolecular porous frameworks, K3(H2O)4[Cu(tza)2(H2O)]2[Cu(Htza)2(H2O)2][BW12O40]·6H2O (1) and H3K3(H2O)3[Cu(Htza)2(H2O)]3[SiW12O44]·14H2O (2) (Htza = tetrazol-1-ylacetic acid), were synthesized and structurally characterized by elemental analysis, infrared spectroscopy, thermal analysis, UV-vis diffuse reflectance spectroscopy, and single-crystal X-ray and powder diffraction. The single-crystal X-ray diffraction analysis indicates that both compounds possess unique petal-like twelve-nucleated Cu-organic units composed of triangular and hexagonal metal-organic loops. In 1, the Cu-organic units are isolated and [BW12O40]5- polyoxoanions are sandwiched between staggered adjacent triangular channels in the structure. However in 2, the Cu-organic units extend into a two-dimensional layered structure, and the [SiW12O44]12- polyoxoanions occupy the larger hexagonal channels in the stacked structure. Both compounds as heterogeneous catalysts can catalyze the selective oxidation of substituted phenols to high value-added p-BQs under mild conditions (60 °C) with TBHP as the oxidant, particularly in the oxidation of 2,3,6-trimethylphenol to 2,3,5-trimethyl-p-benzoquinone (TMBQ, key intermediate in vitamin E production). Within 8-10 min, the yield of TMBQ is close to 100%, and oxidant utilization efficiency is up to 94.2% for 1 and 90.9% for 2. The turnover frequencies of 1 and 2 are as high as 5000 and 4000 h-1, respectively. No obvious decrease in the yield of TMBQ was observed after five cycles, which indicates the excellent sustainability of both compounds. Our study of the catalytic mechanism suggests that there is a two-site synergetic effect: (i) the copper ion acts as the catalytic site of the homolytic radical pathway; and (ii) the polyoxoanion acts as the active center of the heterolytic oxygen atom transfer pathway. This journal is
Bioinspired Total Synthesis of Bussealin e
Twigg, David G.,Baldassarre, Leonardo,Frye, Elizabeth C.,Galloway, Warren R. J. D.,Spring, David R.
, p. 1597 - 1599 (2018/03/23)
The first total synthesis of bussealin E, a natural product with a unique cycloheptadibenzofuran scaffold, is reported. A strategy inspired by a proposed biosynthesis was employed whereby a diphenylpropane derivative underwent an oxidative phenolic coupling to forge the tetracyclic ring system. The synthesis of the diphenylpropane featured a key sp2-sp3 Hiyama coupling between a vinyldisiloxane and a benzylic bromide.
Synthesis of coenzyme Q0 through divanadium-catalyzed oxidation of 3,4,5-trimethoxytoluene with hydrogen peroxide
Zalomaeva, Olga V.,Evtushok, Vasilii Yu.,Maksimov, Gennadii M.,Maksimovskaya, Raisa I.,Kholdeeva, Oxana A.
, p. 5202 - 5209 (2017/04/27)
The selective oxidation of methoxy/methyl-substituted arenes to the corresponding benzoquinones has been first realized using aqueous hydrogen peroxide as a green oxidant, acid tetrabutylammonium salts of the γ-Keggin divanadium-substituted phosphotungstate [γ-PW10O38V2(μ-O)2]5- (I) as a catalyst, and MeCN as a solvent. The presence of the dioxovanadium core in the catalyst is crucial for the catalytic performance. The reaction requires an acid co-catalyst or, alternatively, a highly protonated form of I can be prepared and employed. The industrially relevant oxidation of 3,4,5-trimethoxytoluene gives 2,3-dimethoxy-5-methyl-1,4-benzoquinone (ubiquinone 0 or coenzyme Q0, the key intermediate for coenzyme Q10 and other essential biologically active compounds) with 73% selectivity at 76% arene conversion. The catalyst retains its structure under turnover conditions and can be easily recycled and reused without significant loss of activity and selectivity.
