- Selective Oxidation of 2-Methylnaphthalene to 2-Methyl-1-naphthol by Rhodococcus sp. M192
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About 6000 isolates of microorganisms assimilating methylketones (C3-C6) were tested for their selective oxidation of 2-methylnaphthalene to 2-methyl-1-naphthol. Strain M192 was the highest 2-methyl-1-naphthol producer and was classified as the genus Rhodococcus. The optimal conditions for the site-specific oxidation were studied using resting Rhodococcus sp. M192. The 2-methyl-1-naphthol productivity was specifically increased using methylethylketone as a carbon source, 1-propanol as a solvent to dissolve the substrate, and ethylxanthate or diethyldithiocarbamate as an inhibitor of 2-naphthoic acid (side-product) production. In the presence of these compounds, 2-methylnaphthalene was specifically oxidized at the 1-position without the conversion to 2-naphthoic acid. The productivity of 2-methyl-1-naphthol was about 90 μM from 1 mM 2-methylnaphthalene.
- Taguchi, Hisataka,Kita, Shunbun,Kobayashi, Motoo,Tani, Yoshiki
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Read Online
- Controlling the Gold(I)-Catalyzed 1,5-Allenene Reaction: Construction of Fused Rings with Excellent Diastereoselectivity
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In the present study, the gold(I)-catalyzed reaction of 1,5-allenenes was controlled in such a way that instead of a [2 + 3] cycloaddition, a 5-exo-cyclization with the formation of a carbocation occurred. The latter could be trapped with both oxygen and carbon nucleophiles. In the investigated system, fused tricyclic frameworks with three contiguous stereocenters with excellent chemo- and diastereoselectivity in up to 95% yield were obtained.
- Haberhauer, Gebhard,Semleit, Nina
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supporting information
p. 9635 - 9639
(2021/12/06)
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- Green preparation method of menadione sodium bisulfite
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The invention provides a preparation method of menadione sodium bisulfite. The method comprises the following steps of: by using cheap and easily available 3, 4-dihydro-1 (2H)-naphthalenone as a raw material, carrying out halogenation-elimination to obtain 1-naphthol; carrying out methylation reaction to generate 2-methyl-1-naphthol; carrying out air oxidation on the 2-methyl-1-naphthol to obtain 2-methyl-1, 4-naphthoquinone; and carrying out addition reaction on the 2-methyl-1, 4-naphthoquinone and sodium hydrogen sulfite so as to obtain the menadione sodium bisulfite. The method has the advantages of cheap and easily available raw materials, low cost, safe, simple and convenient process operation, less process wastewater generation, green and environment-friendly performance, high stability of raw materials and intermediate products, high reaction activity and selectivity, easy realization of reaction conditions, few side reactions and high product purity and yield, and can facilitate the industrial production of the menadione sodium bisulfite.
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- Preparation method of menadione sodium hydrogen sulfite
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The invention provides a preparation method of menadione sodium hydrogen sulfite. The preparation method comprises the following steps of: by taking alpha-methyl-gamma-butyrolactone and benzene as raw materials, preparing 2-methyl-3, 4-dihydro-1 (2H)-naphthalenone through Friedel-Crafts reaction; carrying out halogenation reaction on the 2-methyl-3, 4-dihydro-1 (2H)-naphthalenone and a halogenation reagent at the ortho position of carbonyl, and carrying out alkali elimination to prepare 2-methyl-1-naphthol; oxidizing the 2-methyl-1-naphthol through air to obtain 2-methyl-1, 4-naphthoquinone; and carrying out addition reaction on the 2-methyl-1, 4-naphthoquinone and sodium hydrogen sulfite to prepare the menadione sodium hydrogen sulfite. According to the method, the raw materials are cheap, easily available and low in cost; the process operation is safe, simple and convenient, less process wastewater is generated, and the method is green and environment-friendly; and the stability of the raw materials and intermediate products is high, high reaction activity and selectivity are high, reaction conditions are easy to realize, side reactions are few, the purity and yield of the product are high, and industrial production of the menadione sodium bisulfite can be facilitated.
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- Site-selective Oxidative Dearomatization of Phenols and Naphthols into ortho-Quinols or Epoxy ortho-Quinols using Oxone as the Source of Dimethyldioxirane
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A novel reactivity of dimethyldioxirane, generated in situ from Oxone and acetone, with substituted phenols and naphthols is reported. This methodology allowed the synthesis of ortho-quinols or epoxy ortho-quinols from a site-selective oxidative dearomatization process, with good yields under very mild conditions. A short total synthesis of natural product lacinilene C methyl ether is also described using this process as the key step. (Figure presented.).
- Cabrera-Afonso, María J.,Carre?o, M. Carmen,Urbano, Antonio
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supporting information
(2019/08/21)
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- Photocatalytic hydrogen evolution of 1-tetralones to α-naphthols by continuous-flow technology
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Taking advantage of the synergy between photocatalysis and cobaloxime catalysis, the keto-enol radical cation of 1-tetralones becomes compatible with the transformation of various 1-tetralones into α-naphthols and H2 by virtue of the continuous-flow approach without any sacrificial oxidants under unusually mild conditions.
- He, Xu,Zheng, Yi-Wen,Lei, Tao,Liu, Wen-Qiang,Chen, Bin,Feng, Ke,Tung, Chen-Ho,Wu, Li-Zhu
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p. 3337 - 3341
(2019/07/10)
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- Formal Total Synthesis of Hybocarpone Enabled by Visible-Light-Promoted Benzannulation
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The formal total synthesis of hybocarpone was achieved in eight steps from commercially available 1,2,4-trimethoxybenzene. Key transformations include a visible-light-promoted benzannulation to construct the key α-naphthol intermediate and a modified CAN-mediated dimerization/hydration cascade sequence to generate the vicinal all-carbon quaternary centers in a stereocontrolled manner. The total synthesis of boryquinone was also achieved in seven steps.
- Chen, Wei,Guo, Renyu,Yang, Zhen,Gong, Jianxian
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p. 15524 - 15532
(2019/01/03)
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- Efficient cross-coupling of aryl/alkenyl triflates with acyclic secondary alkylboronic acids
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Aryl-secondary alkyl cross-coupling with aryl sulfonate esters as coupling partners remains a significant challenge. Efficient cross-coupling between aryl/alkenyl triflates and acyclic secondary alkylboronic acids is realized for the first time to provide a series of sterically congested acyclic secondary alkyl arenes/olefins in good to excellent yields. The employment of sterically bulky P,PO ligand L1/L2 is crucial for the high yields and selectivities. The method has enabled a concise and 4-step synthesis of a key intermediate of male contraceptive agent and PAF antagonist gossypol.
- Si, Tengda,Li, Bowen,Xiong, Wenrui,Xu, Bin,Tang, Wenjun
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supporting information
p. 9903 - 9909
(2017/12/12)
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- Oxidative coupling of 1-naphthols over noble and base metal catalysts
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Bismuth-promoted platinum catalysts were tested for the oxidative coupling of 2- and 4-substituted 1-naphthols at different temperatures and ambient pressure. The principal final products are the 3,3'-substituted 1,1'-binaphthalenylidene-4,4'- diones and the 4,4'-substituted 2,2'-binaphthalenylidene-1,1'- diones, respectively. Hydrogen peroxide was used as the oxidant. Only naphthols with electron-donating substituents reacted. The corresponding binaphthalenyl diols can be considered as reaction intermediates. Yields of up to 99% were obtained from 2-methyl-1-naphthol as the starting material within 20 minutes. Probably for steric reasons, the diol is the final product obtained from 2-ethyl-1-naphthol. For 4-methoxy- 1-naphthol the outcome is determined by the reaction temperature. At 25 8C the expected 1,1'-dione is the major product, whereas at 60 8C 1'-hydroxy-4'-methoxy-2,2'-binaphthalenyl- 1,4-dione is formed; the loss of one methoxy unit and the preservation of the hydroxy group can be explained by the competitive cleavage of one of the two O-Me bonds at higher temperature. Unpromoted platinum and a range of other metallic catalysts, including gold and Raney nickel, were also found to be active. The products obtained are brightly colored solids that could be used as dyes. The method described is truly catalytic and environmentally benign. The potential of the technique justifies further research to expand on the applicability of this novel method.
- Maphoru, Mabuatsela V.,Heveling, Josef,Pillai, Sreejarani K.
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- Substituent-induced regioselective hydroxylation of the aromatic C-H bond on naphthalene with metachloroperbenzoic acid catalyzed by F20TPPMnCl
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The regioselective hydroxylation of the aromatic C-H bond on a series of naphthalenes with different β-substituent R (R = H, Me, Et, i-Pr, OMe, COOH, Br, etc.) was studied, and the substituent effect on the regioselectivity was investigated. The electron-donating substituent afforded the aromatic C-H bond hydroxylation at the 1α position with more than 80% selectivity, while the electron-withdrawing substituent afforded the aromatic C-H bond hydroxylation at the 4α position with more than 60% selectivity of β-substituted naphthalene hydroxylated with metachloroperbenzoic acid catalyzed by tetrakis(pentafluorophenyl)porphyrin manganese(III) chloride. The research showed that the steric and electronic effects of the substituent appeared to play a significant role in determining the regioselectivity, and the electronic effect was of more importance than the steric effect of the substituent in the current situation. The studies may provide additional proofs for the stepwise mechanism of the aromatic C-H bond hydroxylation through a cationic intermediate. Copyright
- Chen, Chang-Di,Sheng, Wen-Bing,Shi, Guo-Jun,Guo, Can-Cheng
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- Synthesis of substituted α-tetralones and substituted 1-naphthols via regioselective ring expansion of 1-acyl-1-indanol skeleton
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Substituted 1-acyl-1-indanols were prepared using the corresponding readily commercially available substituted indanones as starting materials. Treatment of each 1-acyl-1-indanol derivative with sodium methoxide in hot methanol furnished a regiospecific 2-hydroxy-α-tetralone derivative, which was an α-keto rearrangement product. Each substituted 2-hydroxy-α-tetralone then underwent dehydration to afford the corresponding 1-naphthol derivative.
- Yang, Te-Fang,Wang, Kuan-Yu,Li, Hsuan-Wei,Tseng, Yang-Chan,Lien, Tai-Chen
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scheme or table
p. 585 - 588
(2012/02/01)
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- Oxidative bromination of ketones using ammonium bromide and oxone
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A highly efficient, environmentally safe and economic method for selective α-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and β-keto esters and α,α-dibromination of 1,3-diketones and β-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone as an oxidant. The reaction proceeds at ambient temperature and yields range from moderate to excellent. Bromination of unsymmetrical ketones takes place at the less substituted α-position predominantly. Aromatisation of tetralones is also carried out with this reagent system.
- MacHarla, Arun Kumar,Chozhiyath Nappunni, Rohitha,Marri, Mahender Reddy,Peraka, Swamy,Nama, Narender
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scheme or table
p. 191 - 195
(2012/01/17)
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- Benzannulation for the regiodefined synthesis of 2-alkyl/aryl-1-naphthols: Total synthesis of arnottin i
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The annulation of phthalides with α-alkyl/arylacrylates in the presence of LDA/LHMDS is shown to directly give alkyl/aryl-1-naphthols. The method involving a novel dealkoxycarbonylation obviates the regiochemical issues in the synthesis of polysubstituted naphthalenes, and it forms the key step in a three-step total synthesis of arnottin I, a naphthobenzopyranone natural product.
- Mal, Dipakranjan,Jana, Amit Kumar,Mitra, Prithiba,Ghosh, Ketaki
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experimental part
p. 3392 - 3398
(2011/06/22)
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- Practical imidazole-based phosphine ligands for selective palladium-catalyzed hydroxylation of aryl halides
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(Chemical Equation Presented) The phenol countdown: Novel imidazole-based phosphine ligands are synthesized on scales up to 100 g by a convenient lithiation-phosphorylation method. The phosphines are stable towards air and moisture and are successfully applied as ligands in the palladium-catalyzed selective hydroxylation of aryl halides (see scheme, dba=dibenzylideneacetone).
- Schulz, Thomas,Torborg, Christian,Schaeffner, Benjamin,Huang, Jun,Zapf, Alexander,Kadyrov, Renat,Boerner, Armin,Beller, Matthias
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supporting information; experimental part
p. 918 - 921
(2009/05/15)
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- An easy two-step reduction of salicylic acids and alcohols to 2-methylphenols
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Salicylic acids and alcohols can be reduced to 2-methylphenols by a simple two steps procedure. Reaction conditions were optimized carrying out a study on the solvent effect and the amount of the reducing agent. The improved procedure resulted particularly useful in the synthesis of deuterated building blocks of biological interest. Georg Thieme Verlag Stuttgart.
- Mazzini, Francesco,Salvadori, Piero
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p. 2479 - 2481
(2007/10/03)
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- Ruthenium-catalyzed aromatization of enediynes via highly regioselective nucleophilic additions on a π-alkyne functionality. A useful method for the synthesis of functionalized benzene derivatives
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TpRu(PPh3)(CH3CN)2PF6 (10 mol %) catalyst effected the nucleophilic addition of water, alcohols, aniline, acetylacetone, pyrroles, and dimethyl malonate to unfunctionalized enediynes under suitable conditions (100 °C, 12-24 h) and gave functionalized benzene products in good yields. In this novel cyclization, nucleophiles very regioselectively attack the internal C1′ alkyne carbon of enediynes to give benzene derivatives as a single regioisomer. Experiments with methoxy substituents exclude the possible involvement of naphthyl cations as reaction intermediates in the cyclization of (o-ethynylphenyl) alkynes. Deuterium-labeling experiments indicate that the catalytically active species is ruthenium-π-alkyne rather than ruthenium-vinylidene species. This hypothesis is further confirmed by the aromatization of o-(2′-iodoethynyl)phenyl alkynes with alcohols. We propose a nucleophilic addition/insertion mechanism for this nucleophilic aromatization on the basis of a series of experiments.
- Odedra, Arjan,Wu, Chang-Jung,Pratap, Taduri Bhanu,Huang, Chun-Wei,Ran, Ying-Fen,Liu, Rai-Shung
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p. 3406 - 3412
(2007/10/03)
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- REDOX PROCESS PARTICULARLY FOR THE PRODUCTION OF MENADIONE AND USE OF POLYOXOMETALATES
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The present invention relates to a redox process particularly but not exclusively for producing menadione, which uses Keggin-type heteropolycompounds as oxidizing agents. These compounds are polyoxometalates containing phosphorus, molybdenum, tungsten, vanadium and oxygen, which by virtue of their chemical properties can be used as oxidizers in many redox processes. This redox process can be applied advantageously to products obtained by virtue of a new process of alkylation of 1-naphthol with alcohols. In a particularly preferred case of combination between the alkylation process and the redox process, the 1-naphthol is alkylated with methanol to 2-methyl-l-naphthol, which is then oxidized to menadione.
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- Observations on the synthesis of photochromic naphthopyrans
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1-Naphthol reacts with 1,1-diarylprop-2-yn-1-ols 5a,b, under alumina catalysis, by two pathways to give the photochromic naphtho[1,2-b]pyrans 6a,b, together with the propenylidenenaphthalenones 7a,b, representatives of a new class of merocyanine dyes. With 2-methyl-1-naphthol, formation of the photochrome is suppressed; the only products are merocyanines 7c,d. The cyclocondensation of 2-naphthol with 5a,b proceeds much more efficiently, to give the naphtho[2,1-b]pyrans 14a,b. Pyran formation is not suppressed from either 1-bromo- or 1-(4 -methoxyphenyl)-2-naphthol; reaction with 5a,b merely results in expulsion of the C-1 substituent. An alternative pathway supervenes in the reaction of 1-methyl-2-naphthol with 5a to give the benz[e]indanone 17, the constitution of which was determined by X-ray crystallography. Reaction of the 1,3,3-triarylpropynols 19a,b with 1-naphthol affords the naphthopyrans 20 together with merocyanines 21, whilst the isomeric pyrans 23 are efficiently produced from 2-naphthol. The configuration of merocyanines 7a and 21a was unequivocally established by X-ray crystallography. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Gabbutt, Christopher D.,Heron, B. Mark,Instone, Alicia C.,Thomas, David A.,Partington, Steven M.,Hursthouse, Michael B.,Gelbrich, Thomas
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p. 1220 - 1230
(2007/10/03)
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- Catalytic Alkylation of 1-Naphthol with Methanol
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The reaction of 1-naphthol with methanol in the presence of mordenite catalysts was studied. The synthesis conditions ensuring high yields of methylnaphthols, methylnaphthalenes, or methoxynaphthalene were determined.
- Agaev,Nazarova
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p. 558 - 560
(2007/10/03)
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- Photochemical reactions of diazodihydronaphthalenones in cyclic ethers
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Photolysis of 4-diazonaphthalen-1(4H)-one (1a), 2-methyl-4-diazonaphthalen-1(4H)-one (1b) and 4-diazo-2-nitronaphthalen-1(4H)-one (1c) in neat THF and 1,4-dioxane produced a variety of products depending on the 2-substituent and the solvent. While 1a and
- Zhang, Wei,Shao, Xiangfeng,Yang, Li,Liu, Zhong-Li,Chow, Yuan L.
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p. 1029 - 1032
(2007/10/03)
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- Asymmetric Fluorination of Enolates with Nonracemic N-Fluoro-2,10-Camphorsultams
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The asymmetric "electrophilic" fluorination of tertiary enolates by nonracemic N-fluoro-2,10-camphorsultams 3 affords quaternary α-fluoro carbonyl compounds in modest yield and ee. The highest asymmetric induction was observed for the fluorination of the sodium enolate of 2-methyl-1-tetralone (8a) by (-)-N-fluoro-2,10-(3,3-dichlorocamphorsultam) (3b) to give (S)-(+)-2-fluoro-2-methyl-1-tetralone (9a) in 70percent ee. The absolute configuration was established by X-ray crystallography of the corresponding diastereomeric β-hydroxy sulfoximine prepared from (±)-9a and the Johnson reagent. The asymmetric induction exhibited by 3 is opposite to that of the closely related enolate hydroxylation reagents nonracemic (camphorylsulfonyl)oxaziridines 4. The N-fluoro sultams 3 were prepared by fluorination (10percent F2/N2) of the corresponding sultams 5.
- Davis, Franklin A.,Zhou, Ping,Murphy, Christopher K.,Sundarababu, Gajendran,Qi, Hongyan,Han, Wei,Przeslawski, Robert M.,Chen, Bang-Chi,Carroll, Patrick J.
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p. 2273 - 2280
(2007/10/03)
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- Alkylierung von 1-Naphthol mit Alkoholen an einem Eisenoxidkatalysator
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Keywords: Alkylierungen; Eisenverbindungen; Katalyse; Naphthole
- Grabowska, Hanna,Mista, Wlodzimierz,Syper, Ludwik,Wrzyszcz, Jozef,Zawadzki, Miroslaw
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p. 1682 - 1684
(2007/10/03)
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- Synthesis of 2-methyl-1-naphthol
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4-Halo-1-naphthol is reacted with a secondary amine and formaldehyde to produce a reaction mixture containing a Mannich base which is hydrogenated to produce 2-methyl-1-naphthol. Advantageously, the procedure can be carried out in one pot.
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- Microbial Conversion of 2-Methylnaphthalene to 2-Methyl-1-naphthol and Menadione
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Microbial conversion of 2-methylnaphthalene to 2-methyl-1-naphthol and menadione was investigated.One hundred and twenty-eight strains among 1283 strains isolated using methylethylketone as a sole carbon source showed the activity to oxidize 2-methylnaphthalene to 2-methyl-1-naphthol and menadione of more than 0.1 μM for 2 days.Optimization of reaction conditions using strain M502 resulted in improvement of the productivity.These products were isolated and identified by comparing with authentic samples on UV, MS, and NMR spectra.The results gave enough evidence to prove that microbial products were 2-methyl-1-naphthol and menadione.
- Taguchi, Hisataka,Kita, Shunbun,Tani, Yoshiki
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p. 2001 - 2003
(2007/10/02)
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- Stereoselective synthesis of disubstituted naphthalene-1,2- oxides
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Spiroepoxy naphthalenones, obtained from the stereoselective oxidation of 2-hydroxyalkyl-1-naphthols with sodium periodate, were converted to naphthalene-1,2-oxides by reaction with methyllithium followed by Payne rearrangement.
- Tius,Reddy
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p. 859 - 869
(2007/10/02)
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- Process for producing 2-methyl-1-naphthol
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2-Methyl-1-naphthol is obtained by isomerization of 2-methylene-1-tetralone. For the isomerization of 2-methylene-1-tetralone there is used a Pd-, Rh- or Ru-based catalyst that has been previously treated with hydrogen gas. 2-Methylene-1-tetralone synthesized from 1-tetralone by the Mannich reaction can be used for this purpose.
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- Regioselectivity in the Reactions of Methoxydehydrobenzenes with Furans. Part 3. 3-Methoxyfuran and Methoxydehydrobenzenes and the Chemistry of their Adducts
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The cycloadditions of methoxydehydrobenzenes containing a 3-methoxy group and 3-methoxyfuran are highly regioselective.The adducts, 1,4-dihydro-2-methoxy-1,4-epoxynaphthalenes, undergo mild acid-catalysed hydrolysis providing, first, an isolable 1,2,3,4-tetrahydro-2-methoxy-1,4-epoxynaphthalen-2-ol, and then a 3,4-dihydro-1,4-epoxynaphthalen-2(1H)-one.The chemistry of these ketones is explored.One of them, 3,4-dihydro-5-methoxy-1,4-epoxynaphthalen-2(1H)-one, readily undergoes catalytic reduction to yield the hexahydro-1,4-epoxynaphthalene-2,5(1H,4aH)-dione.The X-ray mo lecular structure of this dione and of the 2-monobrosyl ester of the derived diol are reported.Treatment of the above adducts with trifluoroacetic acid and acetic anhydride provides a convenient synthesis of 1-acetoxy-2-methoxynaphthalenes.
- Baker, Robert W.,Baker, Teresa M. (nee Nicoletti),Birkbeck, Anthony A.,Giles, Robin G. F.,Sargent, Melvyn V.,et al.
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p. 1589 - 1600
(2007/10/02)
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- Process for producing azo pigment
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A process for producing an azo pigment, which comprises coupling an aromatic diazonium compound with 3-hydroxy-2-naphthoic acid and at least one binaphthol and optionally, laking the resulting pigment.
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- ORTHO-LITHIATION OF PHENOLS USING THE BIS(DIMETHYLAMINO)PHOSPHORYL GROUP AS A DIRECTING GROUP
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Aryl tetramethylphosphorodiamidates were effectively lithiated with sec-BuLi at -105 deg C to give ortho-lithiated species which provide ortho-substituted phosphates by treatment with a variety of electrophiles.KEYWORDS lithiation; phenol; bis(dimethylamino)phosphoryl group; phosphate; aryl tetramethylphosphorodiamidate
- Watanabe, Mitsuaki,Date, Mutsuhiro,Kawanishi, Kenji,Tsukazaki, Masao,Furukawa, Sunao
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p. 2564 - 2566
(2007/10/02)
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- Synthesis and Autoxidation of 2,3,4-Trimethylnaphthalen-1-ol and Related Naphthalen-1-ols
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The oxidation of 2-methylnaphthalene, 1,2-dimethylnaphthalene, 2,3-dimethylnaphthalene, and 1,2,3-trimethylnaphthalene by lead tetraacetate in dichloroacetic acid and chloroform gave fair to low yields of the dichloroacetyl derivatives of 2-methylnaphthalen-1-ol, 3,4-dimethylnaphthalen-1-ol, 2,3-dimethylnaphthalen-1-ol, and 2,3,4-trimethylnaphthalen-1-ol respectively.In the case of 1,3-dimethylnaphthalene, dichloroacetoxylation was not observed, and the only isolated product was the binaphthyl (10). 2,3,4-Trimethylnapthalen-1-ol, obtained on hydrolysis of the dichloroac etyl derivative, was very sensitive to oxygen even in the solid state, and when shaken in chloroform in an oxygen atmosphere gave 4-hydroperoxy-2,3,4-trimethylnaphthalen-1-(4H)-one (14).A study of the autoxidation of the naphthalen-1-ols (7), (19) and (20) led to the conclusion that the oxygen-sensitivity of (11) resulted from a 4,5 peri interaction.
- Greenland, Harry,Pinhey, John T.,Sternhell, Sever
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p. 325 - 331
(2007/10/02)
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- Process for the selective production of dihydroxybenzenes
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The known nuclear hydroxylation of phenol or substituted phenols or phenol ethers with organic solutions of hydrogen peroxide in the presence of a catalyst is carried out in improved manner by employing both (1) a special, practically water free solution of hydrogen peroxide in an organic solvent which forms an azeotrope with water, which azeotrope boils below the boiling point of hydrogen peroxide, and (2) selenium dioxide as a catalyst. Through this, the nuclear hydroxylation is substantially simpler than previously. Besides, for the first time, it is possible to control the ortho to para ratio or the two ortho ratios to each other.
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- Anionic Aromatic Ring Annelation of o-Allylbenzamides. Regiospecific Synthesis of Naphthols and Naphthoquinones
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o-Allylbenzamides 2, available from 1 by directed ortho methalation or transition metal catalyzed cross-coupling reactions, undergo MeLi-induced cyclization to give 1-naphthols 3, some of which are immediate precursors for oxygenated naphthoquinones 6 and 7
- Sibi, M.P.,Dankwardt, J.W.,Snieckus, V.
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p. 271 - 273
(2007/10/02)
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- The Photochemistry of 2-Acetoxynaphthalen-1(2H)-ones
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The photochemistry of the 2-acetoxynaphthalen-1(2H)-ones (4), (13), (20), and (26) has been examined.In each case there was rapid formation of a mixture of products, which arose either by homolytic dissociation of the C-OAc bond of by rearrangement involving acetoxy group migration.Two types of rearrangement were observed.The first involved 1,2-acetoxy group with C(2)-C(4) bond formation to give the dihydrocyclopropindenones (7), (15), (22), and (28).This reaction, which is stereospecific, yields the endo-6-acetoxy isomer only, and it is thought to proceed by a concerted non-ionic pathway.The second rearrangement, which is believed to have an ionic mechanism, resulted in formation of 3-acetoxynaphthols from naphthalenones (4) and (26), and 4-acetoxynaphthols form naphthalenones (13) and (20), in which the 3-position is substituted.
- Greenland, Harry,Pinhey, John P.,Sternhell, Sever
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p. 1789 - 1796
(2007/10/02)
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- Synthesis of Menadione
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New methods conceptually different from previous approaches are described for the preparation of 2-methyl-1,4-naphthoquinone (menadione), an antihemorrhagic agent.Recently the bisulphite adduct of menadione has been shown to be a promising plant growth regulator.
- Rao, A. V. Rama,Deshpande, V. H.,Ravichandran, K.
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p. 233 - 235
(2007/10/02)
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- COMPETITION BETWEEN NUCLEAR AND SIDE-CHAIN SUBSTITUTION IN THE OXIDATION OF SOME ALKYLAROMATIC COMPOUNDS BY CERIUM(IV) AMMONIUM NITRATE AND COBALT(III) ACETATE
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The distribution between nuclear and side-chain substitution (N:S ratio) in the oxidations of m-methoxytoluene, 2-methylnaphtalene, mesitylene, and fluorene by cerium(IV) ammonium nitrate (CAN) and cobalt(III) acetate in acetic acid has been determined.The two oxidants exhibit remarkably different behaviours, the propensity for nuclear substitution being much stronger with CAN than with Co(OAc)3.For example, with m-methoxytoluene, CAN affords only products of nuclear acetoxylation, whereas Co(OAc)3 gives side-chain acetoxylation exclusively.The N:S ratio and the isomeric distribution for the CAN-induced reactions are consistent with a mechanism involving a common radical cation intermediate for the side-chain and nuclear substitution.The same mechanism might hold in the reactions with Co(OAc)3; however, in this case, the simultaneous operation of two different mechanisms is an additional possibility: a radical cation mechanism for the nuclear substitution and a hydrogen atom transfer mechanism for the side-chain reaction.
- Baciocchi, Enrico,Rol, Cesare,Sebastiani, Giovanni V.
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p. 513 - 518
(2007/10/02)
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- Preparation of 2-Alkyl-1-naphthols and 1-Alkyl-2-naphthols
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C-Alkylation of 1-naphthol and 2-naphthol with n-butyllithium and dialkyl sulphate easily afford 2-alkyl-1-naphthols and 1-alkyl-2-naphthols respectively in relatively good yields.
- Saidi, Mohammad R.
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- Hydride Eliminations, IX. - Aromatization of Arenocyclohexanones
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Arenocyclohexanones 1 can be aromatized via their silyl enol ethers 2 to phenol derivates 5 with the aid of trityl salts 7, or 2,6-dichloro-3,5-dicyano-p-benzoquinone (6a) or tetrachloro-p-benzoquinone (6b).The method is distinctly milder than classical aromatizations utilizing sulfur, selenium or metal catalysts.The method cannot be applied to aliphatic silyl enol ethers for obtaining α,β-unsaturated carbonyl compounds.Rather, one observes in certain cases α-tritylations.
- Reetz, Manfred T.,Stephan, Wilfried
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p. 533 - 541
(2007/10/02)
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