Synthesis of 2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl Naphthalene: A Product from the Isomerisation of Diels-Alder Adducts of Both 5-Methyl- and 6-Methyl-2-acetyl-1,4-benzoquinone with 1,3-Butadiene

2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl-naphthalene was synthesised via Diels-Alder addition of 2-acetyl-3-methyl-1,4-benzoquinone to buta-1,3-diene followed by enolisation. It was identical with material obtained by pyridine-induced acetyl migration from the 1,3-butadiene adducts of both 3- and 6-methyl-2-acetyl-1,4-benzoquinone.     

光控化学振荡器的设计(英文)

This article reviewed recent progresses in the design of a new class of chemical oscillators and developed a generic model that could qualitatively reproduce those photochemical oscillations seen in experiments. The two oscillators discussed in this report are based on the photolysis of 1,4-benzoquinone and its derivatives, in which external illumination is vital in initiating and sustaining the reaction processes. Nonlinear behavior in these two photo-controlled chemical oscillators are analyzed as a function of light intensity and the initial concentration of reagents including 1,4-benzoquinone, 1,4-hydroquinone, 2-methyl-1,4-benzoquinone, bromate, and sulfuric acid. A generic model proposed initially for the uncatalyzed bromate-aromatic compound reactions was modified here to account for the photolysis of 1,4-benzoquinone or 2-methyl-1,4-benzoquinone. The modified model qualitatively reproduced chemical oscillations and their dependence on light intensity.     

A chemical oscillator based on the photoreduction of 2-methyl-1,4-benzoquinone

This study investigated bromate-2-methyl-1,4-benzoquinone photoreaction in a batch reactor, in which the photoreduction of 2-methyl-1,4-benzoquinone plays a vital role in initiating and sustaining the reaction process. Transient oscillatory phenomena are observed over broad reaction conditions, but a phase diagram in the bromate and sulfuric acid concentration plane shows that the nonlinear behavior is more sensitive to the ratio of bromate and acid than their absolute concentrations. Light intensity and the photosensitive substance 2-methyl-1,4-benzoquinone exhibited opposite effects on the induction time of these oscillations, implying that illumination does more than just reduce 2-methyl-benzoquinone. The oscillatory behavior has been qualitatively reproduced with a generic model developed for bromate-aromatic compounds systems.     

Reaction of 1,4-benzoquinones with PH-phosphonium salts

A novel approach has been proposed to the synthesis of phosphonium salts containing a 1,4-dihydroxybenzo fragment via reaction of 2-methyl-1,4-benzoquinone or 2-isopropyl-5-methyl-1,4-benzoquinone with PH-phosphonium salts generated in situ from triphenylphosphine and trifluoromethanesulfonic or trifluoroacetic acid. The structure of the synthesized phosphonium salts was determined by NMR spectroscopy and X-ray analysis.     

利用Diels-Alder反应构建桉烷类倍半萜骨架关键中间体的研究

以3-甲基-1,3-间苯二酚和异戊醛为原料分别合成亲双烯2-甲氧基-6-甲基对苯醌和双烯1-甲氧基-3-异丙基-1,3-丁二烯,通过Diels-Alder反应,高区域选择性地得到桉烷类倍半萜骨架中间体2c.     

Reactivity of N-arylsulfonyl-1,4-benzoquinone imines. Reaction with hydrazoic acid

N-Arylsulfonyl-2-halo-1,4-benzoquinone imines react with hydrazoic acid in boiling acetic acid via two pathways: the 1,4-addition and nucleophilic replacement of the halogen atom by an azido group, followed by the 1,4-addition of HN₃. In the reaction of N-arylsulfonyl-2,6-dihalo-1,4-benzoquinone imines with hydrazoic acid, both halogen atoms are replaced by azido groups, while N-p-tolylsulfonyl-2-methyl-1,4-benzoquinone imine takes up HN₃ molecule according to the 1,4-addition pattern.     

Synthetic transformations of higher terpenoids: XXVIII. Diels-Alder reactions of 16-(trimethylsiloxybutadienyl) labdanoids

15,16-Epoxy-16-(3-trimethylsiloxybuta-1,3-dien-1-yl)labdanoids were synthesized, and their reactions with cyclic dienophiles (1,4-benzoquinone, 1,4-toluquinone, 2-bromo-6-methyl-1,4-benzoquinone, and N-methylmaleimide) were studied. The reactions with unsymmetrically substituted benzoquinones were not selective. Methods for the preparation of hybrid compounds containing furan diterpenoid and substituted naphthoquinone, octahydroisoindoletrione, or hexahydroisoindoledione fragments were proposed.     

醌型木素模型物的光学特性

为探索醌型木素化学结构与颜色的关系,以五种醌型木素模型物2-甲氧基-1,4-苯醌(I)、1,2-苯醌(II)、4-亚烯丙基-2-甲氧基-2,5-环己二烯酮(亚甲基醌)(III)、5-甲氧基-1,4-苯醌-2-氧负离子(IV)和5-甲基-1,4-苯醌-2-氧负离子(V)作为纸浆中醌型木素发色体的代表,在B3LYP/6-311++G(2d,p)水平上获得了它们在乙醇中的稳定基态构型,采用含时密度泛函理论(TD-DFT)在同等水平上计算了其在乙醇溶液中的电子光谱,并分析了它们在可见光范围内的吸收.结果发现:五种模型物在可见光范围内的吸收均源于电子的π→π*跃迁,它们的最大吸收波长顺序依次为IIIIIIIVV,吸光系数顺序依次为IVIVIIIII;漂白过程中生成的醌氧负离子以及邻醌类模型物具有中等大小的吸光系数(ε=1978-3197),吸收波长较长(445.47-552.36 nm),是漂白后纸浆具有颜色的重要原因.对醌类模型物吸收波长较小(414.91 nm),吸光系数大小为中等(ε=2094),亚甲基醌类模型物虽然吸光系数大(ε=31935),但吸收波长较小(407.90 nm),二者对漂白后纸浆的颜色影响较小.     

Cycloaddition of 1-Aryl-3-trimethylsiloxy-1,3-butadienes in the Synthesis of Natural Quinone Analogs

7-Hydroxy-5-(2-methoxyphenyl)-2-methyl-6-R-1,4-naphthoquinones, 8-hydroxy-1-(2-methoxyphenyl)-3-oxo-1,2,3,4-tetrahydro-9,10-anthraquinone, and 2-ethoxycarbonyl-8-hydroxy-1-(2-methoxyphenyl)-3-trimethylsiloxy-1,1a,4,4a-tetrahydro-9,10-anthraquinone were synthesized by reactions of 1-(2-methoxyphenyl)-2-R-3-trimethylsiloxy-1,3-butadienes with 2-bromo-5-methyl-1,4-benzoquinone and juglone. 1-Aryl-2-ethoxycarbonyl-3-trimethylsiloxy-1,3-butadienes reacted with 1,4-naphthoquinone to afford 1-aryl-2-ethoxycarbonyl-3-hydroxy-9,10-anthraquinones and their 4,4a-dihydro derivatives.     

Oxidative free radical reactions between 2-amino-1,4-benzoquinones and carbonyl compounds

The manganese(III) initiated oxidative free radical reactions of 2-amino-1,4-benzoquinone are described. The free radical reaction of 5,6-dimethyl-2-methylamino-1,4-benzoquinone (1) provides a novel method for the synthesis of indole-4,7-dione and indole-2,4,7-trione. High chemoselectivity was observed in different solvents. The regioselectivity of this reaction was also studied with 5-methyl-2-methylamino-1,4-benzoquinone (19). In most cases, indole-4,7-diones 20 and 21 were produced in high regioselectivity.     

Aerobic oxidation of phenol to quinone with copper chloride as catalyst in ionic liquid

Aerobic oxidation of 2,3,6-trimethyl-phenol to trimethyl-1,4-benzoquinone with 2.5 mol% copper(II) chloride as catalyst in ionic liquid 1-n-butyl-3-methyl-imidazolium chloride, [BMIm]Cl, with n-butanol as co-solvent affording 86% yield provides a new alternative to the copper(II) chloride catalysed aerobic oxidation. The advantage of this catalytic system is that only a catalytic amount of copper(II) chloride is necessary. This catalytic system is also applicable for oxidation of 2-methyl-1-naphthol to 2-methyl-1,4-naphthoquinone. This catalytic reaction was systematically investigated under different conditions.     

Application of rhodanine,fluorene and semicarbazide hydrochloride as new spectrophotometric reagents for quinones

New selective and sensitive Spectrophotometric methods for quinone determination are described. Quinone samples are treated with either methanolic solution of rhodanine, fluorene in ammoniacal media or aqueous semicarbazide hydrochloride solution. Semicarbazide is the most sensitive reagent for the determination of 1,4-benzoquinone, 1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone. Quinones substituted with electron withdrawing groups are better determined using rhodanine. The average recovery is 99.1%, 98.7% and 99.2% using rhodanine, fluorene and semicarbazide as reagents, respectively.     

Synthesis of 2-substituted hydroquinone derivatives from 1,4-benzoquinone and allyl ethers

B-Alkylpinacolboranes, derived from rhodium-catalyzed hydroboration of allyl ethers with pinacolborane, react with 1,4-benzoquinone under acidic, oxidizing conditions, to afford, after subsequent hydrogenation, 2-substituted hydroquinones in isolated, purified yields of about 50% based on 1,4-benzoquinone. The product hydroquinones have potential use as precursors to poly(arylene ether) and related aromatic polymers.     

2H-1,4-benzothiazines from the reaction of 2-aminoethanethiol with nascent 4-methyl-o-benzoquinone

4-Methyl-o-benzoquinone, generated oxidatively, reacts readily with 2-aminoethanethiol giving 5-hydroxy-7-methyl-1,3,4-dihydro-2H-1,4-benzothiazine (I) or 5-oxo-7-methyl-8-(2-hydroxy-4-methylphenoxy)-3,5-dihydro-2H-1,4-benzothiazine (VIII), depending on the conditions under which the reaction is performed. Chemical and spectral (uv, ir, nmr and ms) evidence for the assigned structures, as well as the course of the above mentioned reaction is described. A study of the behaviour of compound VIII in the presence of acids and alkalies is also reported.     

苯醌-DNA加合物的毛细管电泳方法研究

采用毛细管电泳相互作用分析法建立了一种直接评价污染物毒性的新方法。分别将毛细管区带电泳、胶柬电动力色谱与配体分离法结合，对苯醌和小牛胸腺DNA混合温育后的体系进行相互作用研究。研究发现，苯醌对小牛胸腺DNA能产生相互作用并形成DNA加合物，获得了苯醌对小牛胸腺DNA有损伤作用的判断。由于苯醌是苯在体内的代谢终产物，因此认为苯醌对DNA的损伤是苯致癌的途径之一。     

A study of the reactions of α-aminoacros with a model aminochrome

Chemical and spectroscopic evidence leads to the conclusion that all common α-aminoacids, with the exception of proline and hydroxyproline, undergo oxidative deamination by the action of the model aminochrome, 4-methyl-5-(1′-pyrrolidyl)-1,2-benzoquinone(2), to give the same intensely greenish-blue phenoxazine dye 3. This new colour-forming reaction may form the basis for a new method for the detection, specifically, of α-aminoacids. Unlike ninhydrin, 2 is not capable to bring about the oxidative deamination of β-amino-acids and amines. As expected, the SH-containing aminoacid cysteine reacts differently with 2, giving a yellow condensation product, identified as 3-carboxy-5-hydroxy-8-methyl-7-(1′-pyrrolidyl)-2H-1,4-ben (7).     

Bridged cyanine dyes. Part 2 . 1-(N-methyl-2-benzothiazolylinio)-3-(N-methyl-2-benzothiazolylene) and 1-(N-methyl-4-pyridinio)-3-(N-methyl-4-pyridylene)cyclopenta-1,4-dienes with fused rings

1,3-Bis(N-methyl-4-pyridyl)- and 1,3-bis(N-methyl-2-benzothiazolyl)-propane diiodides react with 1,2-cyclohexanedione, tetrachloro-1,2- and -1,4-benzoquinone, 2,3-dichloronaphthoquinone, 3,4-dichloromaleimide and 2,3-dichloroquinoxaline to give novel fused ring bridged cyanine dyes.     

质体醌类化合物的合成研究

醌环的取代基对醌类化合物进行光合作用的电子传递过程有很大影响. 我们设想若能在保持与醌环上的甲基相近体积的条件下, 将其中一个甲基换成氯原子, 这样, 这类化合物醌环上的电子密度显然会低于质体醌, 从而进一步研究它们在光合作用中的作用, 有助于进一步阐明光合作用机制, 以3-氯-2-甲基苯胺为原料, 经氧化, 自由烷基化反应, 合成了十六个具有不同长侧链结构的质体醌类似物.     

Synthesis of triprenylated toluquinone and toluhydroquinone metabolites from a marine-derived Penicillium fungus

Two triprenylated toluquinone and toluhydroquinone marine fungal metabolites, 5-methyl-2-[(2′E,6′E)-3′,7′,11′-trimethyl-2′,6′,10′-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione and 5-methyl-2-[(2′E,6′E)-3,7,11-trimethyl-2′,6′,10′-dodecatrienyl]-1,4-benzenediol, were synthesized in four and five steps, respectively, from 2-methyl-1,4-benzoquinone. The synthesis extends the applicability of the oxidative ether cleavage of hydroquinone dimethyl ethers with argentic oxide under acidic conditions to include the oxidative demethylation of polyprenylated-1,4-dimethoxy-toluhydroquinones with a quantitative survival of the oxidation- and acid-sensitive polyprenyl side chain.     

A novel oxidative free radical reaction between 2-amino-1,4-benzoquinones and benzoylacetonitriles

The manganese(III) initiated oxidative free radical reaction between 2-amino-1,4-benzoquinones and benzoylacetonitriles is described. This free radical reaction provides a novel method for the synthesis of spirodione 3 and spirolactone 4. With 5,6-dimethyl-2-methylamino-1,4-benzoquinone, spirodione 3 was obtained exclusively. On the contrary, with 5-methyl-2-methylamino-1,4-benzoquinone, spirolactone 4 was produced in high chemo- and regioselectivity. By heating with sodium acetate, spirodione 3 can be converted to 4 effectively.