- Development of a Cross-Conjugated Vinylogous [4+2] Anionic Annulation and Application to the Total Synthesis of Natural Antibiotic (±)-ABX
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The cross-conjugated vinylogous [4+2] anionic annulation has been newly developed, the cascade process of which has a high preference for regiochemical control and chemoselectivity, giving rise to exclusively Michael-type adducts in moderate to high yields (up to 94 %, 35 examples). By making use of this approach as a key operation, the first total synthesis of natural antibiotic ABX, in racemic form, has been successfully achieved in a concise 7-step sequence with an overall yield of about 20 %.
- Huang, Jing-Kai,Shia, Kak-Shan
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supporting information
p. 6540 - 6545
(2020/03/03)
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- Tuning the Reactivity of Peroxo Anhydrides for Aromatic C-H Bond Oxidation
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Phenol moieties are key structural motifs in many areas of chemical research from polymers to pharmaceuticals. Herein, we report on the design and use of a structurally demanding cyclic peroxide (spiro[bicyclo[2.2.1]heptane-2,4′-[1,2]dioxolane]-3′,5′-dione, P4) for the direct hydroxylation of aromatic substrates. The new peroxide benefits from high thermal stability and can be synthesized from readily available starting materials. The aromatic C-H oxidation using P4 exhibits generally good yields (up to 96%) and appreciable regioselectivities.
- Pilevar, Afsaneh,Hosseini, Abolfazl,?ekutor, Marina,Hausmann, Heike,Becker, Jonathan,Turke, Kevin,Schreiner, Peter R.
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p. 10070 - 10079
(2018/09/06)
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- Generation of arynes by selective cleavage of a carbonphosphorus bond of o-(diarylphosphinyl)aryl triflates using a grignard reagent
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A novel method for generating arynes, including disubsti-tuted benzynes and a dehydrophenoxathiin, is reported. The treatment of easily synthesizable o-(diarylphosphinyl)aryl triflates having two electron-deficient aromatic groups on the phosphorus atom with a phenyl Grignard reagent triggered the efficient generation of arynes by selective cleavage of a carbonphosphorus bond.
- Nishiyama, Yoshitake,Kamada, Shuhei,Yoshida, Suguru,Hosoya, Takamitsu
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p. 1216 - 1219
(2018/09/11)
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- Ambipolar transistor properties of 2,2′-binaphthosemiquinones
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Binaphthosemiquinones are proved to show ambipolar transistor properties. These compounds have characteristic blue colors owing to the small energy gaps, because the quinone part acts as an electron acceptor and the alkoxy group acts as an electron donor. Accordingly, these molecules have an analogous electronic structure to indigo. The crystal structure changes depending on the alkoxy groups, though these compounds generally have stacking structures.
- Higashino, Toshiki,Kumeta, Shohei,Tamura, Sumika,Ando, Yoshio,Ohmori, Ken,Suzuki, Keisuke,Mori, Takehiko
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supporting information
p. 1588 - 1594
(2015/04/27)
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- Condensed compound and organic light emitting diode comprising the same
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Disclosed are a condensed ring compound and an organic light emitting diode. The organic light emitting diode has low driving voltage, high efficiency, high brightness, and long life. The organic light emitting diode includes a first electrode; a second electrode facing the first electrode; and an organic layer interposed between the first electrode and the second electrode, and including a light emitting layer, wherein the organic layer includes one or more kind of condensed ring compound of any one claim among a first claim to 15^th claim.COPYRIGHT KIPO 2015
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Paragraph 0382-0385
(2016/10/27)
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- Role of substituents on the reactivity and product selectivity in reactions of naphthalene derivatives catalyzed by the orphan thermostable cytochrome P450, CYP175A1
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The thermostable nature of CYP175A1 enzyme is of potential interest for the biocatalysis at ambient temperature or at elevated temperature under environmentally benign conditions. Although little is known about the substrate selectivity of this enzyme, the biocatalytic activities of CYP175A1 on different substituted naphthalenes have been studied in oxidative pathway, and the effect of the substituent on the reaction has been determined. The enzyme first acts as a peroxygenase to convert these substituted naphthalenes to the corresponding naphthols, which subsequently undergo in-situ oxidative dimerization to form dyes of different colors possibly by the peroxidase-type activity of CYP175A1. The product analyses and kinetic measurements suggested that the presence of electron releasing substituent (ERS) in the substrate enhanced the substrate conversion, whereas the presence of electron withdrawing substituent (EWS) in the substrate drastically reduced the substrate conversion. The position of the ERS in the substrate was also found to play an important role in the transformation of the substrate. The results further demonstrate that mutation of the Leu80 residue to Phe enhances the reactivity of the enzyme by favoring the substrate association in the active site. The observed rates of the enzymatic oxygenation reaction of the substituted naphthalenes followed the Hammett correlation of substituent effect, supporting aromatic electrophilic substitution mechanism catalyzed by the cytochrome P450 enzyme.
- Banerjee, Shibdas,Goyal, Sandeep,Mazumdar, Shyamalava
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- Acceleration of the Dakin reaction by trifluoroacetic acid
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An acceleration of the Dakin reaction caused by addition of trifluoroacetic acid is described. The modified protocol converts aromatic aldehydes to the corresponding phenols within 4 hours at room temperature by means of hydrogen peroxide in acidic medium. This acceleration is attributed to the stability of hydrogen peroxide in an acidic medium. This modified protocol provides alternative and easy access to important phenolic precursors that have been used in the synthesis of various natural products.
- Natu, Arun D.,Burde, Ameya S.,Limaye, Rohan A.,Paradkar, Madhusudan V.
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p. 381 - 382
(2014/07/08)
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- Generation of arynes triggered by sulfoxidemetal exchange reaction of ortho-sulfinylaryl triflates
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Arynes were efficiently generated from readily available ortho-sulfinylaryl triflates by the treatment with phenylmagnesium bromide in tetrahydrofuran at 78 C. Aryne generation was initiated by a rapid sulfoxidemetal exchange reaction, followed by the immediate elimination of the ortho-OTf group. Various arynophiles efficiently reacted with arynes generated by this method within 10min, providing the corresponding adducts in high yields.
- Yoshida, Suguru,Uchida, Keisuke,Hosoya, Takamitsu
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p. 116 - 118
(2014/01/23)
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- Chemo- and regioselective direct hydroxylation of arenes with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
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Peroxide in, phenol out: The catalyst [-PW10O38V 2(μ-OH)2]3- showed high activity in the hydroxylation of various aromatic compounds with aqueous H2O 2. The system was regioselective, producing para-phenols from monosubstituted benzene derivatives. Furthermore, alkylarenes with reactive side-chain Ca spa 3-H bonds could be chemoselectively hydroxylated without significant formation of side-chain oxygenated products. Copyright
- Kamata, Keigo,Yamaura, Taiyo,Mizuno, Noritaka
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supporting information; experimental part
p. 7275 - 7278
(2012/08/28)
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- Synthesis of functionalized 1,4-dihydro-9,10-anthraquinones and anthraquinones by ring closing metathesis using Grubbs' catalyst
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A general and straightforward synthesis of anthraquinones was developed, in which diallylation of 1,4-naphthoquinones, followed by Ring Closing Metathesis (RCM) of the resulting diallylnaphthoquinones with Grubbs' catalyst and subsequent dehydrogenation using Pd/C afforded the desired anthraquinones with regiocontrol of substituents and in good yields.
- Van Nguyen, Tuyen,D'Hooghe, Matthias,Pattyn, Siegfried,De Kimpe, Norbert
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p. 1913 - 1916
(2007/10/03)
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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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- 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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- Process for functionalising a phenolic compound carrying an electron-donating group
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The invention concerns a method for functionalizing a phenolic compound bearing an electron-donor group, in said group para position, inter alia a method for the amidoalkylation of a phenolic compound bearing an electron-donor group, and more particularly, a phenolic compound bearing an electron-donor group preferably, in the hydroxyl group ortho position. The method for functionalizing in para position with respect to an electron-donor group carried by a phenolic compound is characterised in that the phenolic compound bearing an electron-donor group is subjected to the following steps: a first step which consists of protecting the hydroxyl group in the form of a sulphonic ester function; a second step which consists in reacting the protected phenolic compound with an electrophilic reagent; optionally, a third step deprotecting the hydroxyl group.
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- Synthesis of 1,3-disubstituted naphtho[2,3-c]pyran-5,10-diones
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Two convenient and simple methods for the synthesis of 1,3-disubstituted naphtho[2,3-c]pyran-5,10-diones, which involve the introduction of acylmethyl groups onto 2-(1-hydroxyethyl)-1,4-naphthoquinones and subsequent base- and acid-induced ring closure, were developed.
- Nguyen Van, Tuyen,Kesteleyn, Bart,De Kimpe, Norbert
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p. 4213 - 4219
(2007/10/03)
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- Process for the two-stage oxidation dyeing of keratin fibers with a manganese complex or salt and a 4-substituted 1-naphthol, and dyeing kit
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A process for the two-stage oxidation dyeing of keratin fibers by applying to the keratin fibers: in a first stage, at least one composition A containing at least one manganese salt and/or a manganese complex, in a second stage, at least one composition B having a pH of greater than or equal to 6, and resulting from the extemporaneous mixing of at least one composition B1 containing at least one 4-substituted 1-naphthol and at least one composition B2 containing at least one oxidizing agent, and corresponding multi-compartment dyeing kit.
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- Rhodium Carbenoid Mediated Cyclizations of o-Alkynyl-Substituted α-Diazoacetophenones
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o-Alkynyl-substituted α-diazoacetophenones undergo facile cyclization to indenone derivatives upon treatment with catalytic quantities of Rh(II) carboxylates.A variety of structural influences were encountered by varying the nature of the substituent group attached to the alkyne carbon atom.The cyclization reaction involves addition of a rhodium stabilized carbenoid onto the acetylenic ?-bond to generate a vinyl carbenoid.The vinyl carbenoid was found to undergo both CH and CC migration as well as δ-CH insertion into the alkyl backbone.Different catalysts were shown to result in significant variation in the product ratios for these reactions.Treatment of o-(5-(allyloxy)-1-pentynyl)-α-diazoacetophenone with rhodium(II) mandelate afforded 2-(2-propen-1-yl)-2-(1-oxo-1H-indenyl)-2,3,4,5-tetrahydrofuran in high yield.The formation of this compound involves initial formation of a vinyl carbenoid which reacts with the neighboring oxygen atom to give an oxonium ylide which subsequently undergoes a 2,3-sigmatropic rearrangement.When 2-ethynyl-α-diazoacetophenone is used, only products derived from 6-endo closure are observed.Substituted o-alkynyl α-diazoacetophenones give products derived from 5-exo cyclization.The mode of ring closure is controlled by both steric and electronic factors.
- Padwa, Albert,Krumpe, Keith E.,Kassir, Jamal M.
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p. 4940 - 4948
(2007/10/02)
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- The Baeyer-Villiger Oxidation of Aromatic Aldehydes and Ketones with Hydrogen Peroxide Catalyzed by Selenium Compounds
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A series of organoselenium compounds was investigated as activators of hydrogen peroxide in the Baeyer-Villiger oxidation.As a result, a convenient and cheap method for transformation of aromatic aldehydes, having polycondensed ring systems or electron-donating substituents, and polymethoxy derivatives of acetophenone, into phenols was elaborated.This method utilizes hydrogen peroxide activated by areneseleninic acids, as oxidizing agent.
- Syper, Ludwik
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p. 167 - 172
(2007/10/02)
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- Dimeric Naphthoquinones, 13. Synthesis of m-Substituted 4-Methoxy-1-naphthols - β-Haloalkyl Ethers as Protective Groups in Phenols
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m-Substituted naphthohydroquinone monoethers are difficult to synthesize by direct alkylation.They are conveniently obtainable now in the following way: Acid-catalyzed reaction of naphthohydroquinones with β-haloethyl alcohols affords monoesters 5 in high yield which are conventionally alkylated forming 6.In 6 the protective group is cleaved off via the vinyl ether or, under milder conditions, by bromine/iodine exchange and fragmentation with zink. - Key words: Naphthols, Protective Groups, Haloalkyl Ethers
- Laatsch, Hartmut
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p. 534 - 542
(2007/10/02)
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- Dimeric Naphthoquinones, XI. - Oxidation Products of Substituted Binaphthyls
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1',4,4'-Trimethoxy-2,2'-binaphthyl-1-ol (7a) is oxidized in high yield forming the quinone 8a or the cyclic acetal 22.Under acidic conditions, both compounds are easily transferred into substituted dinaphthofurans.
- Laatsch, Hartmut
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p. 1367 - 1381
(2007/10/02)
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- Synthesis of 4-Methoxypropranolol, a Suitable Internal Standard for the Determination of Propranolol and 4-Hydroxypropranolol by HPLC
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The synthesis of 4-methoxypropranolol is described.The structure of the intermediates and of the final product is secured by the usual spectroscopical methods.
- Remon, Jean-Paul,Gyselinck, Patrick,Synave, Robrecht,Severen, Robert Van,Braeckmann, Pieter,et al.
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p. 432 - 435
(2007/10/02)
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- Chemistry of Quinone Derivatives. Quinone Monoketals via Hydrolysis of Electrochemically Derived Quinone Bisketals
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The monohydrolysis of nine naphthoquinone bisketals and nine benzoquinone bisketals has been studied.In the acetamido, bromo, methyl, methoxy, and thiomethyl monosubstituted compounds, hydrolysis occurs at the ketal more distant from the substituent.The regiochemistry is nearly exclusive in the naphthoquinone series and is highly selective in the benzoquinone series.For disubstituted benzoquinone and naphthoquinone bisketals, the monohydrolysis is often regiospecific but substituent dependent.The origin of the regioselectivity in the reactions is briefly discussed.
- Henton, Daniel R.,Anderson, Keith,Manning, Michael J.,Swenton, John S.
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p. 3422 - 3433
(2007/10/02)
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- Dimeric Naphthoquinones, II. - Simple and Regioselective Synthesis of Naphthoquinol Monoalkyl Ethers via 2,3-Dihydronaphthoquinones
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On catalysis of hydrogen chloride or thionyl chloride, 1,4-naphthalenediole (2a) reacts with primary or secundary alcohols via the tautomeric 2,3-dihydronaphthoquinone (9) to give naphthoquinol monoalkyl ethers 2b-n in high yields.The influence of the substitution pattern on the regioselectivity of the reaction has been investigated.
- Laatsch, Hartmut
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p. 140 - 157
(2007/10/02)
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