- Preparation of artificial urushi via an environmentally benign process
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"Artificial urushi" has been developed by laccase-catalyzed curing of new urushiol analogues. The analogues were designed and conveniently synthesized by regioselective acylation of phenol derivatives having a primary alcohol with unsaturated fatty acids using lipase as catalyst. The curing of the catechol derivative having a linolenoyl group proceeded in the presence of acetone powder from Chinese urushi, yielding the crosslinked film ("artificial urushi") with high hardness and gloss surface, which are comparable with those of natural urushi coating. The analogues obtained from vanillyl alcohol were also cured. FT-IR monitoring of the curing showed that the crosslinking mechanism was similar to that of the natural urushi. The curing of the urushiol analogues in the presence of starch-urea phosphate took place to give the artificial urushi consisting exclusively of synthetic compounds.
- Ikeda, Ryohei,Tanaka, Hozumi,Oyabu, Hiroshi,Uyama, Hiroshi,Kobayashi, Shiro
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Read Online
- Thiols Act as Methyl Traps in the Biocatalytic Demethylation of Guaiacol Derivatives
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Demethylating methyl phenyl ethers is challenging, especially when the products are catechol derivatives prone to follow-up reactions. For biocatalytic demethylation, monooxygenases have previously been described requiring molecular oxygen which may cause oxidative side reactions. Here we show that such compounds can be demethylated anaerobically by using cobalamin-dependent methyltransferases exploiting thiols like ethyl 3-mercaptopropionate as a methyl trap. Using just two equivalents of this reagent, a broad spectrum of substituted guaiacol derivatives were demethylated, with conversions mostly above 90 %. This strategy was used to prepare the highly valuable antioxidant hydroxytyrosol on a one-gram scale in 97 % isolated yield.
- Grimm, Christopher,Kroutil, Wolfgang,Pompei, Simona,Schiller, Christine,Schober, Lukas
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supporting information
p. 16906 - 16910
(2021/07/02)
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- Phenolic constituents from the twigs of Betula schmidtii collected in Goesan, Korea
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Six undescribed phenolic derivatives along with thirty two known compounds were isolated from the twigs of Betula schmidtii. The chemical structures were characterized through extensive spectroscopic analysis and chemical methods. All known compounds were first isolated in this plant. The anti-inflammatory effect of the isolates was tested by measuring nitric oxide production in lipopolysaccharide-activated BV-2 cells. Isotachioside, 4-allyl-2-hydrophenyl 1-O-β-D-apiosyl-(1 → 6)-β-D-glucopyranoside, genistein 5-O-β-D-glucoside, and prunetinoside showed a slight potency to lower the NO production against LPS-activated microglia with IC50 values of 23.9, 25.3, 28.8, and 34.0 μM, respectively.
- Park, Kyoung Jin,Cha, Joon Min,Subedi, Lalita,Kim, Sun Yeou,Lee, Kang Ro
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- Biocatalytic Methyl Ether Cleavage: Characterization of the Corrinoid-Dependent Methyl Transfer System from Desulfitobacterium hafniense
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The ether functionality represents a very common motif in organic chemistry and especially the methyl ether is commonly found in natural products. Its formation and cleavage can be achieved via countless chemical procedures. Nevertheless, since in particular the cleavage often involves harsh reaction conditions, milder alternatives are highly demanded. Very recently, we have reported on a biocatalytic shuttle catalysis concept for reversible cleavage and formation of phenolic O-methyl ethers employing a corrinoid-dependent methyl transferase system from the anaerobic organism Desulfitobacterium hafniense. Here we report the technical study of this system, focusing on the demethylation of guaiacol as model reaction. The optimal buffer-, pH-, temperature- and cofactor-preferences were determined as well as the influence of organic co-solvents. Beside methyl cobalamin also hydroxocobalamin turned out to be a suitable cofactor species, although the latter required activation. Various O-methyl phenyl ethers were successfully demethylated with conversions up to 82% at 10 mM substrate concentration. (Figure presented.).
- Richter, Nina,Farnberger, Judith E.,Pompei, Simona,Grimm, Christopher,Skibar, Wolfgang,Zepeck, Ferdinand,Kroutil, Wolfgang
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p. 2688 - 2695
(2019/03/28)
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- Temperature-Directed Biocatalysis for the Sustainable Production of Aromatic Aldehydes or Alcohols
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The biosynthesis of aromatic aldehydes and alcohols from renewable resources is currently receiving considerable attention because of an increase in demand, finite fossil resources, and growing environmental concerns. Here, a temperature-directed whole-cell catalyst was developed by using two novel enzymes from a thermophilic actinomycete. Ferulic acid, a model lignin derivative, was efficiently converted into vanillyl alcohol at a reaction temperature at 30 °C. However, when the temperature was increased to 50 °C, ferulic acid was mainly converted into vanillin with a productivity of 1.1 g L?1 h?1. This is due to the fact that the redundant endogenous alcohol dehydrogenases (ADHs) are not active at this temperature while the functional enzymes from the thermophilic strain remain active. As the biocatalyst could convert many other renewable cinnamic acid derivatives into their corresponding aromatic aldehydes/alcohols, this novel strategy may be extended to generate a vast array of valuable aldehydes or alcohols.
- Ni, Jun,Gao, Yan-Yan,Tao, Fei,Liu, Hong-Yu,Xu, Ping
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supporting information
p. 1214 - 1217
(2018/01/27)
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- The metabolic fate of ortho-quinones derived from catecholamine metabolites
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ortho-Quinones are produced in vivo through the oxidation of catecholic substrates by enzymes such as tyrosinase or by transition metalions. Neuromelanin, a dark pigment present in the substantia nigra and locus coeruleus of the brain, is produced from dopamine (DA) and norepinephrine (NE) via an interaction with cysteine, but it also incorporates their alcoholic and acidic metabolites. In this study we examined the metabolic fate of ortho-quinones derived from the catecholamine metabolites, 3,4-dihydroxyphenylethanol (DOPE), 3,4-dihydroxyphenylethylene glycol (DOPEG), 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylmandelic acid (DOMA). The oxidation of catecholic substrates by mushroom tyrosinase was followed by UV-visible spectrophotometry. HPLC analysis after reduction with NaBH4 or ascorbic acid enabled measurement of the half-lives of ortho-quinones and the identification of their reaction products. Spectrophotometric examination showed that the ortho-quinones initially formed underwent extensive degradation at pH 6.8. HPLC analysis showed that DOPE-quinone and DOPEG-quinone degraded with half-lives of 15 and 30 min at pH 6.8, respectively, and >100 min at pH 5.3. The major product from DOPE-quinone was DOPEG which was produced through the addition of a water molecule to the quinone methide intermediate. DOPEG-quinone yielded a ketone, 2-oxo-DOPE, through the quinone methide intermediate. DOPAC-quinone and DOMA-quinone degraded immediately with decarboxylation of the ortho-quinone intermediates to form 3,4-dihydroxybenzylalcohol (DHBAlc) and 3,4-dihydroxybenzaldehyde (DHBAld), respectively. DHBAlc-quinone was converted to DHBAld with a half-life of 9 min, while DHBAld-quinone degraded rapidly with a half-life of 3 min. This study confirmed the fact that ortho-quinones from DOPE, DOPEG, DOPAC and DOMA are converted to quinone methide tautomers as common intermediates, through proton rearrangement or decarboxylation. The unstable quinone methides afford stable alcoholic or carbonyl products.
- Ito, Shosuke,Yamanaka, Yuta,Ojika, Makoto,Wakamatsu, Kazumasa
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- CSJ acting as a versatile highly efficient greener resource for organic transformations
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Simple, new, greener and efficient alternatives to the existing protocols have been developed for the reduction of aromatic aldehydes to their corresponding alcohols, decarboxylation of substituted benzoic acids (C6-C1) and substituted cinnamic acids (C6-C3) with a hydroxyl group at the para position with respect to the acid group to corresponding phenolic compounds and vinyl phenols respectively by using a natural feedstock, cucumber juice (CSJ), which acts as a greener solvent system, performing a substrate-selective reaction. Additionally, the hydrolysis of the acetyl as well as the benzoyl group of aromatic compounds has been carried out to afford excellent yield by CSJ.
- Maity, Himadri Sekhar,Misra, Kaushik,Mahata, Tanushree,Nag, Ahindra
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p. 24446 - 24450
(2016/03/15)
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- Photochemistry of bisphenol F in aqueous solutions: A mechanistic study
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In the present work aqueous photochemistry of bisphenol F has been studied by means of stationary (282 nm) and laser flash photolysis (266 nm). Photoionization with formation of hydrated electron - phenoxyl radical pair was observed to be the main primary photochemical process (φmono = 2 × 10-2). Phenoxyl radical decays in recombination and reaction with superoxide anion radical formed during scavenging of hydrated electron by dissolved oxygen. The quantum yield of BPF photodegradation was evaluated to be 2 × 10-3 upon 282 nm exposure. The main primary product of BPF photolysis determined by LC-MS is hydroxylated BPF.
- Salomatova, Victoria,Pozdnyakov, Ivan,Sherin, Peter,Grivin, Vjacheslav,Plyusnin, Victor
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- Design, synthesis and biological evaluation of small molecular polyphenols as entry inhibitors against H5N1
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To find novel compounds against H5N1, three series of known or novel small molecular polyphenols were synthesized and tested in vitro for anti-H5N1 activity. In addition, the preliminary structure-antiviral activity relationships were elaborated. The results showed that some small molecular polyphenols had better anti-H5N1 activity, and could serve as novel virus entry inhibitors against H 5N1, likely targeting to HA2 protein. Noticeably, compound 4a showed the strongest activity against H5N1 among these compounds, and the molecular modeling analysis also suggested that this compound might target to HA2 protein. Therefore, compound 4a is well qualified to serve as a lead compound or scaffold for the further development of H 5N1 entry inhibitor.
- Yang, Jian,Yang, Jing Xiang,Zhang, Fang,Chen, Gang,Pan, Wei,Yu, Rui,Wu, Shuwen,Tien, Po
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p. 2680 - 2684
(2014/06/09)
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- Electrophilicity and nucleophilicity of commonly used aldehydes
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The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
- Pratihar, Sanjay
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p. 5781 - 5788
(2014/07/22)
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- Preliminary antiproliferative evaluation of natural, synthetic benzaldehydes and benzyl alcohols
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Vanillin, o-vanillin, natural and synthetic benzaldehydes and benzyl alcohols were assessed for antiproliferative effects using different human cell lines. Benzyl alcohols were synthesized from benzaldehydes reduced with NaBH4 in methanol solution. A new method for deprotection of ether compounds with TiCl4 solution was achieved with better performance, than previously reported. Twenty four compounds were tested. The in vitro growth inhibition assay was based on sulphorhodamine dye to quantify cell viability. Catechol 9 derived from piperonal as well as compounds 4 and 12 showed higher cytotoxicity on breast and prostate cancer cell lines (MDA-MB-231 and PC-3 respectively). o-Vanillin 5 has the highest cytotoxicity for all cell lines. IC50 values of 35.40 ± 4.2 ?M Breast MDA-MB231; 47.10 ± 3.8 ?M Prostate PC-3; 72.50 + 5.4 ?M Prostate DU-145; 85.10 + 6.5 ?M and Colon HT-29, were obtained without toxicity towards dermal human fibroblast (DHF cells).
- Madrid, Alejandro,Espinoza, Luis,Catalan, Karen,Gonzalez, Cesar,Montenegro, Ivan,Mellado, Marco,Werner, Enrique,Cuellar, Mauricio,Villena, Joan
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p. 1814 - 1816
(2014/03/21)
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- Hydroxylation of p-substituted phenols by tyrosinase: Further insight into the mechanism of tyrosinase activity
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A study of the monophenolase activity of tyrosinase by measuring the steady state rate with a group of p-substituted monophenols provides the following kinetic information: kcatm and the Michaelis constant, KMm. Analysis of these data taking into account chemical shifts of the carbon atom supporting the hydroxyl group (δ) and σp+, enables a mechanism to be proposed for the transformation of monophenols into o-diphenols, in which the first step is a nucleophilic attack on the copper atom on the form Eox (attack of the oxygen of the hydroxyl group of C-1 on the copper atom) followed by an electrophilic attack (attack of the hydroperoxide group on the ortho position with respect to the hydroxyl group of the benzene ring, electrophilic aromatic substitution with a reaction constant ρ of -1.75). These steps show the same dependency on the electronic effect of the substituent groups in C-4. Furthermore, a study of a solvent deuterium isotope effect on the oxidation of monophenols by tyrosinase points to an appreciable isotopic effect. In a proton inventory study with a series of p-substituted phenols, the representation of kcatfn/kcatf0 against n (atom fractions of deuterium), where kcatfn is the catalytic constant for a molar fraction of deuterium (n) and kcatf0 is the corresponding kinetic parameter in a water solution, was linear for all substrates. These results indicate that only one of the proton transfer processes from the hydroxyl groups involved the catalytic cycle is responsible for the isotope effects. We suggest that this step is the proton transfer from the hydroxyl group of C-1 to the peroxide of the oxytyrosinase form (Eox). After the nucleophilic attack, the incorporation of the oxygen in the benzene ring occurs by means of an electrophilic aromatic substitution mechanism in which there is no isotopic effect.
- Munoz-Munoz, Jose Luis,Berna, Jose,Garcia-Molina, Maria del Mar,Garcia-Molina, Francisco,Garcia-Ruiz, Pedro Antonio,Varon, Ramon,Rodriguez-Lopez, Jose N.,Garcia-Canovas, Francisco
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scheme or table
p. 228 - 233
(2012/10/18)
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- New greener alternatives for bioreduction of aromatic aldehydes and decarboxylation of aromatic acids using juice of fruits
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Cocos nucifera L. and Borassus flabellifer L. juices act as bio catalytic system for the reduction of aromatic aldehydes to alcohols and selective decarboxylation of substituted cinnamic acid to styrene and substituted benzoic acid to polyphenolic compound. Both juices exhibit good activity when aromatic aldehydes and aromatic acids contain electron-donating groups at specific positions. Moreover, C. nucifera juice exhibits good result for the reduction and decarboxylation properties than B. flabellifer juice under the same reaction condition.
- Misra, Kaushik,Maity, Himadri Sekhar,Chanda, Subhankar,Nag, Ahindra
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experimental part
p. 92 - 95
(2012/09/22)
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- PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
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- Reduction of carbonyl compounds with NaBH4 under ultrasound irradiation and aprotic condition
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A variety of carbonyl compounds are reduced to their corresponding alcohols with sodium borohydride under ultrasound irradiation and aprotic condition. Reduction reactions are performed in THF at room temperature or under reflux condition. The product alcohols were obtained in good to excellent yields. The chemoselective reduction of aldehydes over ketones was achieved successfully with this system.
- Zeynizadeh, Behzad,Yahyaei, Saiedeh
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p. 704 - 710
(2007/10/03)
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- Titanyl Acetylacetonate as an Efficient Catalyst for a Mild and Convenient Reduction of Carbonyl Compounds with NaBH4 under Aprotic Condition
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Titanyl acetylacetonate, TiO(acac)2, is used as an efficient catalyst for the reduction of carbonyl compounds with sodium borohydride under aprotic condition. Reduction reactions are performed in CH3CN and THF. The corresponding alcohols are obtained in high to excellent yields and the chemoselective reduction of aldehydes over ketones is achieved successfully.
- Zeynizadeh, Behzad
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p. 1220 - 1226
(2007/10/03)
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- Modified hydroborate agent: (2,2′-bipyridyl)(tetrahydroborato)zinc complex, [Zn(BH4)2(bpy)], as a new, stable, efficient ligand-metal hydroborate and chemoselective reducing agent
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(2,2′-Bipyridyl)(tetrahydroborato)zinc complex, [Zn(BH4)2(bpy)], is a new white stable compound which has been used for efficient reduction of variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α, β-unsaturated carbonyl compounds (1,2-reduction) to their corresponding alcohols in acetonitrile at room temperature. Excellent chemoselectivity was also observed for the reduction of aldehydes over ketones with this reducing agent.
- Zeynizadeh, Behzad
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p. 317 - 326
(2007/10/03)
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- Mild and efficient method for reduction of aldehydes and ketones with NaBH4 in the presence of Dowex1-x8
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Various aldehydes and ketones are reduced efficiently to alcohols with NaBH4/Dowex1-x8.
- Zeynizadeh, Behzad,Shirini, Farhad
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p. 335 - 339
(2007/10/03)
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- The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds
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Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical coupling and oxalic acid formation were followed. Transition metals increased the reactivities of all the lignin model compounds with hydrogen peroxide in the order Mn2+ > Cu2+ > Fe3+, which is the same as the order of activity toward peroxide decomposition while Mg2+ stabilized the system. Demethylation, radical coupling, and oxalic acid formation were all increased by the presence of transition metals in the system and decreased by the addition of Mg2+. The acceleration of the total degree of reaction and of the demethoxylation reactions improves peroxide bleaching, but the increase in the radical coupling reactions can affect the further bleachability of pulp while the increase in the formation of oxalic acid could lead to a greater probability of scaling.
- Sun, Yujun,Fenster, Michael,Yu, Annie,Berry, Richard M.,Argyropoulos, Dimitris S.
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p. 667 - 675
(2007/10/03)
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- Reaction of vanilmandelic acid and 4-Hydroxybenzyl alcohol derivatives with L-ascorbic acid
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The interaction between vanilmandelic and L-ascorbic acids led to a cyclopent-2-en-one derivative, whereas the reaction or methyl vanilmandelate with L-ascorbic acid yielded 2-furancarboxylic acid as the major product. The model 3-substituted 4-hydroxybenzyl alcohols and L-ascorbic acid produced ascorbigen-type structures, which easily decarboxylated to give mistures of the corresponding 1-aryl-1-deoxyketoses.
- Preobrazhenskaya,Rozhkov,Lazhko,Yudina,Korolev
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p. 6971 - 6976
(2007/10/03)
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- Lanthanoids in Organic Synthesis. I. The Novel Reduction of Carboxylic Acids with Samarium Diiodide-Base System
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Aromatic and aliphatic carboxylic acids were rapidly reduced with samarium diiodide by the addition of base in the presence of protic solvent at room temperature to the corresponding alcohols.Sodium benzoate was similarly reduced with samarium diiodide in the presence of H2O in a good yield.In the similar reactions of benzoic acid derivatives bearing carboxyl, formyl, carbamoyl, methoxyl, and chloro groups, these functional groups were also reduced to the corresponding alcohol or amine derivatives.Interestingly, the carboxyl and formyl groups of benzoic acids were partly reduced into the methyl group.
- Kamochi, Yasuko,Kudo, Tadahiro
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p. 3049 - 3054
(2007/10/02)
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- Hair dyeing composition containing an aryldiamine and a substituted catechol
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A composition for use in the dyeing of keratinous fibre such as hair includes an aqueous anaerobic solution of an aryldiamine and a substituted catechol. Optionally, an aromatic coupling agent can also be incorporated in the composition to modify the shade of color produced. Anaerobic storage conditions can, for example, be maintained by packing the composition in an aerosol container with a halocarbon propellant.
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