- Experimental and semiemprical studies of chemical reactivity of dialkylcadmium reagents addition to α,β-enones
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Experimental and semiempirical calculations were carried out to study the reactivity of dialkylcadmium reagents addition to α,β-enones. It was demonstrated that α,β-enone such as benzoquinone with low lying LUMO energy reacts via single electron transfer (SET) mechanism with the formation of the 1,2 or 1,4-type alkyl addition product depending on the reaction temperature and substrate structure. Site and chemoselectivity in unsymmetrical benzoquinone derivatives are determined by the stability of the cadmium coordinated semienone complex intermediates and the carbon spin densities of these reactive species respectively. On the other hand, by increasing the LUMO energy of α,β-enone system, the reaction mechanism changes from SET to polar addition affording the 1,4-type alkyl addition product. The establishment of a correlation scale between substrate LUMO energies and reaction mechanism presented in this article will be discussed.
- Ghandi, Mehdi,Shahidzadeh, Mansour
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- Phenolic compounds from the insect Blaps japanensis with inhibitory activities towards cancer cells, COX-2, ROCK1 and JAK3
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The insect Blaps japanensis have been used as an ethnomedicine in China for the treatment of several disorders such as cancer and inflammation. Our investigation with this insect led to the isolation of eight new and two known phenolic compounds. The structures of the new compounds, blapsins C?J (1–8), were identified by spectroscopic data. The inhibitory activities of all the compounds except of 9 against human cancer cells (A549, K562 and Huh-7), COX-2, ROCK1, and JAK3 were evaluated. Several compounds were found to be biologically active in these assays.
- Yan, Yong-Ming,Zhu, Hong-Jie,Zhou, Feng-Jiao,Tu, Zheng-Chao,Cheng, Yong-Xian
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- Palladium aminopyridine complexes catalyzed selective benzylic C-H oxidations with peracetic acid
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Four palladium(ii) complexes with tripodal ligands of the tpa family (tpa = tris(2-pyridylmethyl)amine) have been synthesized and X-ray characterized. These complexes efficiently catalyze benzylic C-H oxidation of various substrates with peracetic acid, affording the corresponding ketones in high yields (up to 100%), at 1 mol% catalyst loadings. Complex [(tpa)Pd(OAc)](PF6) with the least sterically demanding ligand tpa demonstrates the highest substrate conversions and ketone selectivities. Preliminary mechanistic data provide evidence in favor of metal complex-mediated rate-limiting benzylic C-H bond cleavage by an electron-deficient oxidant.
- Bryliakov, Konstantin P.,Lubov, Dmitry P.,Lyakin, Oleg Yu.,Rybalova, Tatyana V.,Samsonenko, Denis G.,Talsi, Evgenii P.
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supporting information
p. 11150 - 11156
(2020/09/02)
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- Candida antarctica lipase B-mediated regioselective acylation of dihydroxybenzenes in organic solvents
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Candida antarctica lipase B proved to be a highly active biocatalyst for the direct acylation of phenolic hydroxy groups of substituted hydroquinones and resorcinols, which have rarely been reported so far. More importantly, the acylation reactions took place generally in a markedly regioselective manner: the hydroxy group remote from the substituent was preferentially acylated. In the case of substituted hydroquinones, the selectivity increased with the increase in the bulk of the substituent. Interestingly, the 1-O-monoacylated derivatives were obtained as the sole products in the case of 4-substituted resorcinols.
- Miyazawa, Toshifumi,Hamada, Manabu,Morimoto, Ryohei,Maeda, Yuki
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p. 3915 - 3923
(2015/06/02)
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- Candida antarctica lipase B-catalyzed regioselective deacylation of dihydroxybenzenes acylated at both phenolic hydroxy groups
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Candida antarctica lipase B proved to be highly active in the deacylation of substituted hydroquinones and resorcinols acylated at both phenolic hydroxy groups. The deacylation reactions were much faster than the corresponding direct acylations of these dihydroxybenzenes catalyzed by the same lipase. More importantly, they took place generally in a markedly regioselective manner: the acyloxy group remote from the substituent was preferentially cleaved. The main or exclusive products obtained were the regioisomers of those produced through the direct acylation of the dihydroxybenzenes. In the case of alkyl-substituted hydroquinone derivatives, the regioselectivity increased with an increase in the bulk of the substituent. In the case of 4-substituted diacylated resorcinols, the 3-O-monoacyl derivatives were obtained generally as the sole products. Quite interestingly, some secondary alcohols proved to act as better acyl acceptors than the corresponding primary alcohols in these enzymatic deacylations.
- Miyazawa, Toshifumi,Hamada, Manabu,Morimoto, Ryohei
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- Re2O7 catalyzed dienone-phenol rearrangement
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The dienone-phenol rearrangement of 4,4-disubstituted cyclohexadienones catalyzed by Re2O7 has been described. Multi-substituted phenols can be efficiently obtained in good to excellent yields by employing this catalytic protocol.
- Xia, Zilei,Hu, Jiadong,Shen, Zhigao,Yao, Qizheng,Xie, Weiqing
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p. 38499 - 38502
(2015/06/24)
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- THIAZOLE COMPOUNDS USEFUL AS ACETYL-COA CARBOXYLASE (ACC) INHIBITORS
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The present invention provides thiazole compounds of Formula I or its pharmaceutically acceptable salts, prodrugs, solvates, N-oxide thereof; solvates of pharmaceutically acceptable salts and N-oxides; pharmaceutically acceptable salts of N-oxides, or prodrugs; or combination or mixtures thereof; (I) The present invention further provides a method for preventing or treating a condition that responds to an Acetyl-CoA Carboxylase (ACC) inhibitor by using compounds of formula (I) or ), its pharmaceutically acceptable salts, prodrugs, solvates, N-oxide thereof; solvates of pharmaceutically acceptable salts and N-oxides; pharmaceutically acceptable salts of N-oxides, or prodrugs; or combination or mixtures thereof.
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- Synthesis of the fully glycosylated cyclohexenone core of lomaiviticin A
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We describe two four-step sequences for conversion of the inexpensive reagent ethyl sorbate to either O-allyl-N,N-dimethyl-D-pyrrolosamine or O-allyl-L-oleandrose, protected forms of the 2,6-dldeoxy sugar residues found in the complex bacterial metabolite
- Gholap, Shivajirao L.,Woo, Christina M.,Ravikumar,Herzon, Seth B.
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body text
p. 4322 - 4325
(2009/12/26)
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- Electrophysiological and behavioral activity of secondary metabolites in the confused flour beetle, tribolium confusum
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Several previous studies have addressed pheromone communication in various flour beetles (Coleoptera: Tenebrionidae), including the confused flour beetle, Tribolium confusum (du Val). Different stereoisomers of 4,8-dimethyldecanal (DMD) were reported as the only components of an aggregation pheromone, but the behavioral activity of DMD is low. In the present study, additional previously reported secondary metabolites (benzoquinones and hydrocarbons) were tested for electrophysiological activity (EAG) with both sexes of T. confusum. Two benzoquinones and three monoenic hydrocarbons elicited significant EAG activity from both male and female antennae. There was an elevated male EAG response (vs. the females) to two out of the three hydrocarbons and for both quinones. The EAG-active compounds were subsequently investigated for behavioral activity in a walking bioassay. Benzoquinones are considered toxic and have been assigned a function as alarm substances in flour beetles, but we found that methyl-1, 4-benzoquinone in intermediate concentrations was attractive to both male and female beetles and could therefore act as an aggregation pheromone component. Males were also attracted to ethyl-1,4-benzoquinone. The corresponding hydroquinones, presumed precursors of the benzoquinones, did not elicit any electrophysiological response and were not tested for behavioral activity. The unsaturated hydrocarbons (1-tetradecene, 1-pentadecene, and 1-hexadecene) elicited significant EAG responses from both male and female antennae and were also attractive in the behavioral assay. Our results show that several beetle-produced compounds, in addition to 4,8-dimethyldecanal, may be part of a complex pheromone system in flour beetles and play a role in mediating aggregation in T. confusum.
- Verheggen,Ryne,Olsson,Arnaud,Lognay,Hoegberg,Persson,Haubruge,Loefstedt
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p. 525 - 539
(2008/09/17)
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- Spinazarin and ethylspinazarin, pigments of the sea urchin Scaphechinus mirabilis
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2,3,5,8-Tetrahydroxy-1,4-naphthoquinone (spinazarin) and 6-ethyl-2,3,5,8-tetrahydroxy-1,4-naphthoquinone (ethylspinazarin) were first isolated from the sea urchin Scaphechinus mirabilis. The structures of spinazarins were established based on analysis of spectroscopic data. A preparative synthetic route to ethylspinazarin was proposed.
- Yakubovskaya,Pokhilo,Mishchenko,Anufriev
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p. 819 - 822
(2008/04/05)
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- Secondary alcohols act as better nucleophiles than primary alcohols in the lipase-catalyzed regioselective deacylation of dihydroxybenzenes acylated at both phenolic hydroxyls
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Candida antarctica lipase B (CAL-B) was found to be highly regioselective as well as active in the deacylation of resorcinols and hydroquinones acylated at both phenolic hydroxyls. Contrary to expectation, secondary alcohols acted as better nucleophiles than primary alcohols in these enzymatic deacylations.
- Miyazawa, Toshifumi,Hamada, Manabu,Morimoto, Ryohei,Murashima, Takashi,Yamada, Takashi
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p. 8334 - 8337
(2008/03/14)
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- One step hair coloring compositions using salts
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A hair coloring composition comprising the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an amino phenol, a naphthol, a polyhydric phenol, a catechol and mixtures thereof; wherein the composition comprising one or more oxidative hair coloring agents further comprises al least one water soluble carbonate releasing salts; and optionally a water soluble ammonium salt, is described.
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- Transition metal complexes as dye forming catalysts in hair coloring compositions
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A hair coloring composition comprising a first composition which comprises: (a) a dye forming transition metal salt or complex; which is first applied to the hair; and a second composition which comprises the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an aminophenol, a polyhydric phenol a catechol and mixtures thereof.
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- Enhanced color deposition for hair with sequestering agents
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Hair coloring compositions which comprise: (A) non-nitrogenous chelating agents from the group consisting of polyphosphate; phosphonates; hydroxycarboxylates; polyacrylates; zeolite; and mixtures thereof; (B) an oxidative dye primary intermediate; and (C) an oxidative dye coupler; (D) and water are described. The present invention also relates to a method for coloring hair which comprises contacting said hair with a hair coloring composition as described above.
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- Alkylation and acetal formation using supercritical alcohol without catalyst
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The aromatic ring alkylation of phenols, N-alkylation of aniline, O-alkylation of phenols and acetal formation from acetaldehyde or acetone were examined using supercritical (SC) alcohol without any catalyst. Highly selective syntheses of monoalkylated compounds were achieved for the aromatic ring alkylation and N-alkylation. The O-alkylation proceeded more preferentially than the aromatic ring alkylation for phenols which have a deactivating group. The acetal formation went on in more than 96% selectivity.
- Horikawa, Yoshiteru,Uchino, Yuki,Sako, Takeshi
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p. 232 - 233
(2007/10/03)
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- Evidence for single electron transfer (SET) pathway in the reaction of primary alkylcadmium reagents with p-benzoquinone
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The reaction of primary alkylcadmium reagents with p-benzoquinone at various conditions was studied. On the basis of our results, reaction proceeds through a SET mechanism that forms loose and tight intermediates, which produce quinole (1) and substituted hydroquinone (2). In both cases, hydroquinone (3) is obtained in different yields.
- Shahidzadeh, Mansour,Ghandi, Mehdi
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p. 108 - 111
(2007/10/03)
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- Comparative pulse radiolysis studies of alkyl- and methoxy-substituted semiquinones formed from quinones and hydroquinones
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Absorption spectra and rate constants for the disproportionate of 12 alkyl- and methoxy-substituted semiquinone anion free radicals (Q?-) produced by the one-electron reduction (using CO2?- as a reductant) of 1,4-benzoquinones and 1,4-naphthoquinone (Q) as well the oxidation (using N3? as an oxidant) of the corresponding hydroquinones (QH2) were determined by pulse radiolysis in 50 mM sodium phosphate buffer, pH 7.40 at room temperature. Both spectral and kinetic characteristics of Q?- only moderately depended on whether Q?- was produced from Q or QH2. Spectra of benzosemiquinones display two peaks with maximum at 310-320 nm and ca. 430 nm with the ratio of about 2-2.5. Molar absorption coefficients were determined. Rate constants for Q?- disproportionation (2k1) were correlated with the nature of substituents. While 2k1 was scarcely affected by methyl substitution, Q?- containing isopropyl, tert-butyl and methoxy substituents were visibly more stable than non-substituted and methyl-substituted Q?-.
- Roginsky, Vitaly A.,Pisarenko, Leonid M.,Bors, Wolf,Michel, Christa,Saran, Manfred
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p. 1835 - 1840
(2007/10/03)
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- Metabolic Formation of 4-Methyl-4H-1,3,2-benzodioxaphosphorins from Bis(o-ethylphenyl) Phenylphosphonates in House Flies
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Bis(4-chloro-2-ethylphenyl) phenylphosphonate was metabolically transformed into the corresponding cyclic ester, i.e., 6-chloro-4-methyl-2-phenyl-4H-1,3,2-benzodioxaphosphorin 2-oxide, in houseflies in vivo.In a p-unsubstituted analog, hydroxylation at the para-position of an ester linkage occurred preferably to alpha-hydroxylation with subsequent cyclization.The cyclization was diastereomerically selective, giving predominantly the cis ester.The biological activities of synthesized and related cyclic esters were similar to but weaker than saligenin cyclic phosphorus esters lacking a methyl group at the 4-position.
- Wu, Shao-Yong,Ito, Shigekazu,Eto, Morifusa
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p. 2935 - 2942
(2007/10/02)
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- DEOXYGENATION OF ALDEHYDES AND KETONES WITH SODIUM CYANOBOROHYDRIDE
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Treatment of hydroxy-substituted aromatic aldehydes and ketones with sodium cyanoborohydride yields the corresponding methylene compounds under conditions which favor intermediate carbonium ion formation.
- Elliger, Carl A.
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p. 1315 - 1324
(2007/10/02)
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- Rotational Viscosity Coefficients γ1 for Mixtures of Nematic Liquid Crystals
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The rotational viscosity coefficients γ1 for mixtures of nematic liquid crystals have been determined as a function of temperature and composition.Mixtures of two components with equal clearing temperatures but different molecular lengths, of two homologues, and or a mesogenic and a nonmesogenic compound, together with a system which exhibits an induced smectic phase have been studied.The dependence on composition is understood qualitatively.Far away from the clearing point, the dependence on composition is similar to that of the shear viscosity coefficients in isotropic liquids.At high temperatures, the concentration dependence of γ1 influenced by the order parameter which strongly depends on concentration in systems with different clearing temperatures.
- Kneppe, H.,Schneider, F.
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p. 219 - 230
(2007/10/02)
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- Enzyme-activated oxidative process for coloring hair
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An enzyme-based oxidative process for coloring hair wherein the hair is exposed to a solution having a pH of about 4 to about 10 and containing hydrogen peroxide, soybean peroxidase enzyme and one or more oxidation dye precursors.
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