- Progress towards metal-free radical alkylations of quinones under mild conditions
-
A new method for the radical alkylation of quinones is reported. Lewis basic nitrogen additives increase the efficacy of quinone alkylations from carboxylic acids using catalytic AgNO3 and Selectfluor as a mild oxidant. Electrochemical data sug
- Galloway, Jordan D.,Baxter, Ryan D.
-
-
Read Online
- Radical-mediated synthesis of substituted quinones with organotellurium compounds
-
Carbon-centered radicals generated from the corresponding organotellurium compounds react with a variety of quinones under photo-thermal conditions to give the monoaddition product in good to excellent yield. The reaction can be used for the synthesis of polyprenyl quinoid natural products.
- Yamago, Shigeru,Hashidume, Masahiro,Yoshida, Jun-Ichi
-
-
Read Online
- Quinone C-H Alkylations via Oxidative Radical Processes
-
A brief survey of radical additions to quinones is reported. Carboxylic acids, aldehydes, and unprotected amino acids are compared as alkyl radical precursors for the mono- or bis- C-H alkylation of several quinones. Two methods for radical initiation are discussed comparing inorganic persulfates and Selectfluor as stoichiometric oxidants. Kinetic analysis reveals dramatic differences in the rate of radical initiation depending on the identity of the radical precursor and oxidant. Synthetic strategies for efficiently producing alkyl-quinones are discussed in the context of selecting optimum radical precursors and initiators depending on quinone identity and functional groups present.
- Hamsath, Akil,Galloway, Jordan D.,Baxter, Ryan D.
-
p. 2915 - 2923
(2018/06/12)
-
- Catalytic asymmetric [2+2] cycloaddition between quinones and fulvenes and a subsequent stereoselective isomerization to 2,3-dihydrobenzofurans
-
The catalytic enantioselective [2+2] cycloaddition between quinones and fulvenes was achieved, for the first time, by the use of a chiral copper(ii) complex catalyst. The transformation afforded a series of enantiomerically enriched [6,4,5]-tricyclic cyclobutane derivatives in good yields with excellent regio- and stereoselectivities. Furthermore, the [2+2] adducts could be easily converted into formal [3+2] adducts efficiently and stereoselectively.
- Zheng, Haifeng,Xu, Chaoran,Wang, Yan,Kang, Tengfei,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
-
supporting information
p. 6585 - 6588
(2017/07/10)
-
- Chiral cobalt(II) complex catalyzed Friedel-Crafts aromatization for the synthesis of axially chiral biaryldiols
-
An efficient atroposelective synthesis of axially chiral biaryldiols via asymmetric Friedel-Crafts aromatization between p-quinones and 2-naphthols was developed. A chiral cobalt(ii) complex of N,N′-dioxide enabled the process to generate axially chiral biaryldiols in up to 98% yield and 95% ee. A large range of substituents at different positions of p-quinones and 2-naphthols was tolerable. The configuration of the product and the chiral N,N′-dioxide-Co(ClO4)2 catalyst was identified by X-ray crystal diffraction analysis and a possible catalytic model was suggested.
- Xu, Chaoran,Zheng, Haifeng,Hu, Bowen,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
-
supporting information
p. 9741 - 9744
(2017/09/07)
-
- Silver-Catalyzed Minisci Reactions Using Selectfluor as a Mild Oxidant
-
A new method for silver-catalyzed Minisci reactions using Selectfluor as a mild oxidant is reported. Heteroarenes and quinones both participate in radical C-H alkylation and arylation from a variety of carboxylic and boronic acid radical precursors. Several oxidatively sensitive and highly reactive radical species are successful, providing structures that are challenging to access by other means.
- Galloway, Jordan D.,Mai, Duy N.,Baxter, Ryan D.
-
supporting information
p. 5772 - 5775
(2017/11/10)
-
- Substituent effects in the oxidation of 2-alkyl-1,4-dialkoxybenzenes with ceric ammonium nitrate
-
Increased steric size of alkyl groups and the presence of coordinating atoms on alkoxy groups have both been found to contribute to decreasing yields of diquinones upon reaction of 2-alkyl-1,4-dialkoxybenzenes with CAN. The overall hydrophilicity of the substrates does not appear to be a significant factor in determining the diquinone yield for these reactions.
- Love, Brian E.,Simmons, Alexander L.
-
p. 5712 - 5715
(2016/11/29)
-
- Chemo- and regioselective direct hydroxylation of arenes with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
-
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
-
supporting information; experimental part
p. 7275 - 7278
(2012/08/28)
-
- Ruthenium-catalyzed oxidative dearomatization of phenols to 4-(tert-butylperoxy)cyclohexadienones: Synthesis of 2-substituted quinones from p-substituted phenols
-
The ruthenium-catalyzed oxidation of phenols with tert-butylhydroperoxide efficiently gives the corresponding 4-(tert-butylperoxy)cyclohexadienones. The oxidation proceeds selectively because of ruthenium's ability for rapid single-electron transfer. This biomimetic oxidation reaction is highly useful to obtain the metabolic compounds desired for confirming the safety of medicines and related compounds. Typically, the first metabolic compound of the female hormone estrone is readily obtained by this biomimetic oxidation reaction. The resulting 4-(tert-butylperoxy)cyclohexadienones are versatile synthetic intermediates, which can be transformed into 2-substituted 1,4-benzoquinones by treatment with acid catalysts. Acid-promoted rearrangement followed by a Diels-Alder reaction provides a new strategy for the synthesis of fused cyclic compounds, such as naphthoquinone and anthraquinone derivatives, from readily available phenols. The nonnatural 1,4-diacetoxy steroidal skeleton is obtained by the oxidation of estrone followed by zinc-mediated migration. Vitamin K 3 is synthesized selectively from p-cresol in an overall 79 % yield in 4 steps, and the synthesis includes the ruthenium-catalyzed oxidation.
- Murahashi, Shun-Ichi,Miyaguchi, Noriko,Noda, Shinji,Naota, Takeshi,Fujii, Akiko,Inubushi, Yasutaka,Komiya, Naruyoshi
-
p. 5355 - 5365
(2011/11/14)
-
- Synthesis of 2-substituted quinones, vitamin K3, and vitamin K1 from p-cresol. BF3·OEt2-catalyzed methyl migration of 4-tert-butyldioxycyclohexadienones
-
BF3·OEt2-catalyzed methyl group migration of 4-methyl-4-tert-butyldioxycyclohexadienone, which is obtained by ruthenium-catalyzed oxidation of p-cresol with tert-butyl hydroperoxide, in hexafluoro-2-propanol/toluene gave toluquinone efficiently. The reaction can be applied to the regio-selective short-step syntheses of vitamin K3 and vitamin K1 from p-cresol.
- Murahashi, Shun-Ichi,Fujii, Akiko,Inubushi, Yasutaka,Komiya, Naruyoshi
-
scheme or table
p. 2339 - 2341
(2010/05/19)
-
- Synthesis and characterisation of polymer-anchored oxidovanadium(IV) complexes and their use for the oxidation of styrene and cumene
-
The Schiff bases H2fsal-ea (I), H2fsal-pa (II) and H2fsal-amp (III), derived from 3-formylsalicylic acid and 2-aminoethanol, 3-aminopropanol and 2-amino-2-methylpropanol, respectively, have been connected, by means of covalent bonds, to chloromethylated polystyrene cross-linked with 5% divinylbenzene. On treatment with [VO(acac)2] in dimethylformamide (DMF), these polymer-anchored ligands PS-H2fsal-ea (IV), PS-H2fsal-pa (V) and PS-H2fsal-amp (VI) gave the oxidovanadium(IV) complexes, PS-[VO(fsal-ea)·DMF] (4), PS-[VO(fsal-pa)·DMF) (5) and PS-[VO(fsal-amp)·DMF] (6), respectively. The corresponding neat complexes [VO(fsal-ea)]2 (1), [VO(fsal-pa)]2 (2) and [VO(fsal-amp)]2 (3) have also been similarly prepared. These complexes all exhibit a medium intensity band between 964 and 993 cm-1 in their IR spectra resulting from the V=O stretch. The EPR spectra of the polymer-anchored complexes are characteristics of monomelic VIV centres with a simple S = 1/2 electronic spin and with an axial pattern typical of square pyramidal geometry. Broad features for the neat complexes along with magnetic susceptibility studies suggest the presence of antiferromagnetic exchange interactions between two vanadium centres in close proximity. These catalysts have been tested for the oxidation of styrene and cumene and were found to be efficient. Styrene gives five reaction products namely styrene epoxide, benzaldehyde, 1-phenylethane-1,2-diol, benzoic acid and phenylacetaldehyde, whereas cumene gives acetophenone, 2-phenylpropanal, α-methyl styrene epoxide, 2-phenyl-2-propanol, 2-isopropyl-1,4- benzoquinone and α-methyl styrene. The polymer-anchored heterogeneous catalysts are recyclable. The catalytic activities of the neat complexes have also been examined and compared with the corresponding anchored analogues. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Maurya, Mannar R.,Kumar, Umesh,Manikandan
-
p. 2303 - 2314
(2008/02/12)
-
- A new synthetic route to substituted quinones by radical-mediated coupling of organotellurium compounds with quinones
-
Carbon-centered radicals generated from the corresponding organotellurium compounds react with a variety of quinones under photo-thermal conditions to give the monoaddition product in moderate to excellent yield. The reaction can be used for the synthesis of polyprenyl quinoid natural products and C-glycosides.
- Yamago, Shigeru,Hashidume, Masahiro,Yoshida, Jun-Ichi
-
p. 6805 - 6813
(2007/10/03)
-
- A New Selective Method for the Homolytic Alkylation and Carboxylation of Quinones by Monoesters of Oxalic Acid
-
Alkyl and alkoxycarbonyl radicals were generated by oxidative decarboxylation of oxalic acid monoesters by persulfate; they were then utilized for the selective substitution of quinones.
- Coppa, Fausta,Fontana, Francesca,Lazzarini, Edoardo,Minisci, Francesco
-
p. 1299 - 1302
(2007/10/02)
-
- Reactive dyestuffs
-
Triphendioxazine reactive dyestuffs of the general formula STR1 with the substituent definition given in the description, are outstandingly suitable for dyeing and printing materials containing hydroxyl groups or amide groups. They give red dyeings with high wet- and light-fastnesses.
- -
-
-
- Multiple Electron Oxidation of Phenols by an Oxo Complex of Ruthenium(IV)
-
The kinetics of oxidation of phenol and alkylated phenol derivatives by (2+) and (2+) (bpy is 2,2'-bipyridine and py is pyridine) to give the corresponding quinones have been studied in aqueous solution and in acetonitrile.The reactions are first order in both phenol and Ru(IV)=O(2+) or Ru(III)-OH(2+).They proceed via a detectable intermediate, which is a Ru(II) complex. 18O isotopic labeling experiments show that transfer of the oxo group from Ru(IV)=O(2+) to phenol is quantitative.The reactions are facile.With Ru(IV)=O(2+) as oxidant k(25 deg C, CH3CN) = 1.9 (+/-0.4) E2M-1s-1; with Ru(III)-OH(2+) as oxidant k(25 deg C, CH3CN) = 4.0 (+/-0.4) E1M-1s-1.On the basis of the rate laws, the magnitude of OH/OD and CH/CD kinetic isotope effects, and the 18O labeling results, the most reasonable mechanisms for oxidation of phenol by Ru(IV)=O(2+) appears to be electrophilic attack on the aromatic ring.For Ru(III)-OH(2+), oxidation appears to occur by CH/H atom transfer in CH3CN and OH/H atom transfer in water.
- Seok, Won K.,Meyer, Thomas J.
-
p. 7358 - 7367
(2007/10/02)
-
- Triphendioxazine dyestuffs
-
Triphendioxazine dyestuffs of the formula STR1 having the substituent meanings specified in the descriptive part, are highly suitable for dyeing and printing hydroxyl- or amido-containing materials, in particular fibre materials, and produce wash-fast dyeings and prints.
- -
-
-