- Expedient and simple method for regeneration of alcohols from toluenesulfonates using Mg-MeOH
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Efficient conversion of toluenesulfonates to corresponding alcohols with Mg-MeOH is described.
- Sridhar, Madabhushi,Kumar, B. Ashok,Narender
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- A facile method for deprotection of O-allylphenols
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Allyl aryl ethers can be easily cleaved by the use of 10% Pd/C under the mild and basic conditions.
- Yamada, Makoto,Watanabe, Shin-Ichi,Hoshino, Osamu,Ishizaki, Miyuki,Hayashida, Maiko,Tanaka, Atsuko,Hara, Hiroshi
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- Photoconductive bent-core liquid crystalline radicals with a paramagnetic polar switchable phase
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A series of self-organizing bent-core derivatives 1[12,n], containing a highly π-delocalized stable radical as the central angular structural element, is described. The planarity of the open-shell core permits efficient π-π stacking, which results in the formation of B2 and soft crystalline phases above 100 °C. Optical, XRD and dielectric analyses of 1[12,12] indicate that the ground state of the observed B2 phase is polar antiferroelectric of type SmCAPA exhibiting tristable electro-optical switching. SQUID and EPR measurements revealed strong antiferromagnetic spin-spin exchange interactions below the isotropic phase, which have been estimated at θ = -46 cm-1 with the Curie-Weiss law. Transient photoconductivity was observed in the B2 phase with a hole carrier mobility μh of 1.4 × 10-4 cm2 V-1 s-1
- Shivakumar, Kilingaru I.,Pociecha, Damian,Szczytko, Jacek,Kapu?ciński, Szymon,Monobe, Hirosato,Kaszyński, Piotr
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- Novel synthesis of monoethers of hydroquinone and resorcinol on soluble polymer-supports
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Monoethers of hydroquinone and resorcinol were easily prepared using PEG as soluble polymer-supports, monoprotection group and phase transfer catalyst with good yields and high selectivity of functionlization in homogenous solution.
- Yang, Guichun,Chen, Zuxing,Zhang, Zhaojun,Qiu, Xiaoling
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- Nickel-catalyzed deallylation of aryl allyl ethers with hydrosilanes
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An efficient and mild catalytic deallylation method of aryl allyl ethers is developed, with commercially available Ni(COD)2 as catalyst precursor, simple substituted bipyridine as ligand and air-stable hydrosilanes. The process is compatible with a variety of functional groups and the desired phenol products can be obtained with excellent yields and selectivity. Besides, by detection or isolation of key intermediates, mechanism studies confirm that the deallylation undergoes η3-allylnickel intermediate pathway.
- Ding, Guangni,Fan, Sijie,Wang, Jingyang,Wang, Yu,Wu, Xiaoyu,Xie, Xiaomin,Yang, Liqun,Zhang, Zhaoguo
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- Baeyer-Villiger oxidation of β-aryl substituted unsaturated carbonyl compounds with hydrogen peroxide and catalytic selenium dioxide
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A simple and cheap oxidative procedure using 30% H2O2 and catalytic SeO2 allows to transform 2-aralkylidenecycloalkanones and hydroxy- or alkoxybenzaldehydes to give, in high yields, enollactones and arylformates, respectively.
- Guzman,Mendoza,Garcia,Garibay,Oliveras,Maldonado
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- Synthesis and liquid crystal property of new fluoro coumarin carboxylates
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New liquid crystalline 4-alkoxyphenyl-coumarin-3-carboxylates 6a-e, 7a-g, 8a-e, and 9a-e were prepared by reacting various coumarin-3-carboxylic acids 5a-d with 4-(alkoxy) phenols 4a-g in the presence of 1(3-dimethylaminopropyl-3- ethylcarbodiimide/dimethyl amino pyridine (EDCI/DMAP) as a coupling agent. The structures of the new coumarin derivatives were confirmed by spectral analysis and the liquid crystalline property was established by polarizing optical microscope and by differential scanning calorimetric techniques. The diethyl amine and morpholine were taken as electron-donating and -CF3 as electron-withdrawing groups at the seventh position of the coumarin-3-carboxylic acids to check the mesomorphic property in all new 4-alkoxyphenyl-coumarin-3- carboxylates. Among them, only 4-alkoxyphenyl-7-triflouromethyl-coumarin-3- carboxylates 7a-g exhibited liquid crystalline SmA phase.
- Mahadevan, Kittappa M.,Harishkumar, Hosanagara N.,Masagalli, Jagadeesh N.,Srinivasa, Hosapalya T.
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- Development of a catalytic electron transfer system mediated by transition metal ate complexes: Applicability and tunability of electron-releasing potential for organic transformations
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We have developed a catalytic electron transfer (ET) system composed of a transition metal ate complex (Me3M(II)Li; M = Co(II), Mn(II), Fe(II)) and magnesium. This system (catalytic Me3M(II)Li/Mg) turned out to be effective for various ET reactions, such as the desulfonylation of N-phenylsulfonyl amides, and others (the chemoselective cleavage of O-allyl groups, the reduction of nitro groups, the partial reduction of diketones, and the reductive coupling of diphenyliodonium salt). The ET ability of this system can be tuned by changing the ligands of the ate complexes. This tunability was experimentally and electrochemically demonstrated: alkoxy-ligated and dianion-type ET ate complexes showed attenuated and enhanced reducing abilities, respectively. The modification of the ET abilities was evaluated by means of electrochemical measurements and chemical reactions. These results provide a basis for the design of various tailor-made ET ate complexes.
- Uchiyama, Masanobu,Matsumoto, Yotaro,Nakamura, Shinji,Ohwada, Tomohiko,Kobayashi, Nagao,Yamashita, Natsuno,Matsumiya, Atsushi,Sakamoto, Takao
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- An efficient and selective deprotection of allyl ethers by a CeCl3.7H2O- NaI system
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A mild, novel and chemoselective method for the deprotection of allyl ethers by a CeCl3.7H2O- NaI system is described.
- Thomas, R. Mathew,Reddy, G. Sudhakar,Iyengar
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- Evaluating Gold and Selenium Chemistry for Selective Transformations of Lignin Model Compounds
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Applications of gold and selenium chemistry are reported as novel approaches to promote lignin depolymerization into more valuable chemicals via selective oxidation reactions (alcohol oxidations and Baeyer-Villiger reactions). In this study, we proposed two different oxidative methodologies using Au/SiO2 and phenylseleninic acid resin (PAR) as stable and reusable catalysts to promote selective transformations of the β-O-4 linkage of lignin model compounds. After evaluating the catalytic systems under batch conditions, they were both applied in a packed-bed reactor for continuous flow operations. By using Au/SiO2 as a catalyst under flow conditions, ketones were efficiently obtained (up to 86% conversion) from the oxidation of alcohols with a residence time (tR) of 30 min. In the case of Baeyer-Villiger oxidations catalyzed by phenylseleninic acid resin, the corresponding esters were obtained in up to 91% conversion (tR=30 min). Both systems efficiently catalyzed the conversion of the lignin model compounds. (Figure presented.).
- Santos, Wagner C. C.,Dias, Kevin A.,Santos, Leidaiany P.,Kisukuri, Camila M.,Rodrigues, Thenner S.,Geonmonond, Rafael S.,Camargo, Pedro H. C.,Andrade, Leandro H.
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- LOW-VALENT TITANIUM: A NEW APPROACH TO DEPROTECTION OF ALLYL AND BENZYL GROUPS
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A novel method for the deprotection of allyl and benzyl derivatives of alcohols and phenols by low-valent titanium is reported.The possible mechanism is discussed.
- Kadam, S. M.,Nayak, S. K.,Banerji, A.
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- An efficient and selective deprotecting method for methoxymethyl ethers
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Methoxymethyl ethers were selectively deprotected to the corresponding phenols in high yields by CBr4 and PPh3 in aprotic solvent (ClCH2CH2Cl) under slightly thermal reaction conditions.
- Peng, Yungui,Ji, Changyun,Chen, Yingchun,Huang, Chengzhi,Jiang, Yaozhong
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Read Online
- Catalyst-free photooxidation reaction from 1,4-dihydropyridazine to pyridazine under air
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In the inverse electron-demand Diels–Alder (iEDDA) reactions between tetrazines and strained alkenes, a mixture of 1,4-dihydropyridazine isomers are formed first, and they are then oxidized to pyridazines. Although the products of these related oxidation processes converge as pyridazines, the oxidation rate is quite low with some substrates. In this study, we revealed that 1,4-dihydropyridazines formed in the iEDDA reactions were oxidized to pyridazines by simply irradiating with an ultraviolet light under an air atmosphere. Our experimental results implied that singlet oxygen was formed in the course of the reactions to oxidize the 1,4-dihydropyridazine molecules.
- Fujii, Hideaki,Itoh, Kennosuke,Karaki, Fumika,Kiguchi, Takuto,Konishi, Kazuhide,Sato, Noriko
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supporting information
(2021/09/16)
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- A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2andtBuOK
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A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh2andtBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.
- Pan, Wenjing,Li, Chenchen,Zhu, Haoyin,Li, Fangfang,Li, Tao,Zhao, Wanxiang
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p. 7633 - 7640
(2021/09/22)
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- Synthetic method 4 - alkoxyphenol compounds
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The invention discloses a synthetic method of 4 - alkoxyphenol compounds, and belongs to the field of organic chemical synthesis. The method is as follows: An aryl alkyl ether compound is added to the sealing tube. The catalyst dimerization acetic acid rhodium and the oxidizing agent iodobenzene diethyl ester are added, a solvent trifluoroacetic anhydride is added, and the 4 -alkoxyphenol compound is prepared by heating reaction. To the invention, high regioselectivity direct hydroxylation of the aryl alkyl ether compound is realized, the application range of the substrate is wide, the yield is high, the activity after amplification reaction does not significantly decay, and higher yield is still obtained. The utility model has good practicability and industrial application prospect.
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Paragraph 0038-0040
(2021/09/29)
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- Para -Selective hydroxylation of alkyl aryl ethers
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para-Selective hydroxylation of alkyl aryl ethers is established, which proceeds with a ruthenium(ii) catalyst, hypervalent iodine(iii) and trifluoroacetic anhydride via a radical mechanism. This protocol tolerates a wide scope of substrates and provides a facile and efficient method for preparing clinical drugs monobenzone and pramocaine on a gram scale.
- Zhu, Runqing,Sun, Qianqian,Li, Jing,Li, Luohao,Gao, Qinghe,Wang, Yakun,Fang, Lizhen
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supporting information
p. 13190 - 13193
(2021/12/16)
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- Aryl phenol compound as well as synthesis method and application thereof
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The invention discloses a synthesis method of an aryl phenol compound shown as a formula (3). All systems are carried out in an air or nitrogen atmosphere, and visible light is utilized to excite a photosensitizer for catalyzation. In a reaction solvent, ArNR1R2 as shown in a formula (1) and water as shown in a formula (2) are used as reaction raw materials and react under the auxiliary action of acid to obtain the aryl phenol compound as shown in a formula (3). The ArNR1R2 in the formula (1) can be primary amine and tertiary amine, can also be steroid and amino acid derivatives, and can also be drugs or derivatives of propofol, paracetamol, ibuprofen, oxaprozin, indomethacin and the like. The synthesis method has the advantages of cheap and easily available raw materials, simple reaction operation, mild reaction conditions, high reaction yield and good compatibility of substrate functional groups. The fluid reaction not only can realize amplification of basic chemicals, but also can realize amplification of fine chemicals, such as synthesis of drugs propofol and paracetamol. The invention has wide application prospect and use value.
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Paragraph 0162-0165
(2021/05/12)
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- Benzoic acid resin (BAR): a heterogeneous redox organocatalyst for continuous flow synthesis of benzoquinones from β-O-4 lignin models
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A polymer-bound organocatalyst for Baeyer-Villiger reaction and phenol oxidation under continuous flow conditions is described for the first time.BARhas revealed two catalytic activities that enabled the generation of a novel approach for the synthesis of benzoquinones from β-O-4 lignin models in a one-pot protocol. High catalytic activities (yields up to 98%), selectivities, recyclability and productivity were achieved.
- Dias, Kevin de Aquino,Pereira Junior, Marcus Vinicius Pinto,Andrade, Leandro Helgueira
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supporting information
p. 2308 - 2316
(2021/04/07)
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- BTK Inhibitors and uses thereof
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The invention discloses a bruton's tyrosine kinase (BTK) inhibitor and use thereof. Specifically, the invention provides heteroaromatic compounds or stereoisomers, geometrical isomers, tautomers, racemates, nitrogen oxides, hydrates, solvates, metabolites and pharmaceutically acceptable salts or prodrugs thereof, and pharmaceutical compositions containing the heteroaromatic compounds; the invention also discloses use of the heteroaromatic compounds or the pharmaceutical compositions containing the heteroaromatic compounds in preparation of medicines; the medicines can be used for treating autoimmune diseases, inflammatory diseases or proliferative diseases.
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Paragraph 0640-0645
(2020/05/02)
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- Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
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The invention discloses a method for preparing alcohol and phenol through aerobic hydroxylation reaction of a boric acid derivative in the absence of a photocatalyst, wherein the boric acid derivativeis aryl boronic acid or alkyl boronic acid, and the corresponding target compounds are respectively a phenol-based compound and an alcohol-based compound. According to the method, by using a boric acid derivative as a reaction substrate, an additive is added under a solvent condition, and a hydroxylation reaction is performed under aerobic and illumination conditions to obtain a corresponding target compound. According to the invention, the new strategy is provided for the synthesis of phenols through aerobic hydroxylation of aryl boronic acid without a photocatalyst; the catalyst-free aerobic hydroxylation method for photocatalysis of aryl boronic acid or alkyl boronic acid by using triethylamine as an additive is firstly disclosed; and the new method has advantages of photocatalyst-freecondition, wide substrate range and good functional group compatibility.
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Paragraph 0025-0028; 0030-0032
(2020/01/25)
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- Quantum Dot-Catalyzed Photoreductive Removal of Sulfonyl-Based Protecting Groups
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This Communication describes the use of CuInS2/ZnS quantum dots (QDs) as photocatalysts for the reductive deprotection of aryl sulfonyl-protected phenols. For a series of aryl sulfonates with electron-withdrawing substituents, the rate of deprotection for the corresponding phenyl aryl sulfonates increases with decreasing electrochemical potential for the two electron transfers within the catalytic cycle. The rate of deprotection for a substrate that contains a carboxylic acid, a known QD-binding group, is accelerated by more than a factor of ten from that expected from the electrochemical potential for the transformation, a result that suggests that formation of metastable electron donor–acceptor complexes provides a significant kinetic advantage. This deprotection method does not perturb the common NHBoc or toluenesulfonyl protecting groups and, as demonstrated with an estrone substrate, does not perturb proximate ketones, which are generally vulnerable to many chemical reduction methods used for this class of reactions.
- Perez, Kaitlyn A.,Rogers, Cameron R.,Weiss, Emily A.
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supporting information
p. 14091 - 14095
(2020/06/08)
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- Anchimerically Assisted Selective Cleavage of Acid-Labile Aryl Alkyl Ethers by Aluminum Triiodide and N, N-Dimethylformamide Dimethyl Acetal
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Aluminum triiodide is harnessed by N,N-dimethylformamide dimethyl acetal (DMF-DMA) for the selective cleavage of ethers via neighboring group participation. Various acid-labile functional groups, including carboxylate, allyl, tert-butyldimethylsilyl (TBS), and tert-butoxycarbonyl (Boc), suffer the conditions intact. The method offers an efficient approach to cleaving catechol monoalkyl ethers and to uncovering phenols from acetal-type protecting groups such as methoxymethyl (MOM), methoxyethoxymethyl (MEM), and tetrahydropyranyl (THP) chemoselectively.
- Sang, Dayong,Yue, Huaxin,Zhao, Zhengdong,Yang, Pengtao,Tian, Juan
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p. 6429 - 6440
(2020/07/14)
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- Selective ether bond breaking method of aryl alkyl ether
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The invention discloses a selective aryl alkyl ether cracking method, which comprises that aryl alkyl ether, aluminum iodide and an additive are subjected to a selective ether bond cleavage reaction in an organic solvent at a temperature of -20 DEG C to a reflux temperature to generate phenol and derivatives thereof. The method is mild in condition and simple and convenient to operate, is suitablefor cracking aryl alkyl ether containing o-hydroxyl and o-carbonyl and acetal ether, and can also be used for removing tertiary carbon hydroxyl protecting groups with higher steric hindrance, such astriphenylmethyl, tertiary butyl and the like.
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Paragraph 0253-0257
(2020/09/16)
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- Nickel-catalyzed removal of alkene protecting group of phenols, alcohols via chain walking process
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An efficient nickel-catalyzed removal of alkene protection group under mild condition with high functional group tolerance through chain walking process has been established. Not only phenolic ethers, but also alcoholic ethers can be tolerated with the retention of stereocenter adjacent to hydroxyl group. The new reaction brings the homoallyl group into a start of new type of protecting group.
- Meng, Chenkai,Niu, Haolin,Ning, Juehan,Wu, Wengang,Yi, Jun
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- Photoinduced hydroxylation of arylboronic acids with molecular oxygen under photocatalyst-free conditions
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Photoinduced hydroxylation of boronic acids with molecular oxygen under photocatalyst-free conditions is reported, providing a green entry to a variety of phenols and aliphatic alcohols in a highly concise fashion. This new protocol features photocatalyst-free conditions, wide substrate scope and excellent functional group compatibility.
- Xu, Yu-Ting,Li, Chen-Yuan,Huang, Xiao-Bo,Gao, Wen-Xia,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
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supporting information
p. 4971 - 4975
(2019/09/30)
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- First total synthesis of rhuscholide A, glabralide B and denudalide
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The first total synthesis of rhuscholide A, a benzofuran lactone possessing anti-HIV-1 activity, had been accomplished in 14 linear steps with 10.6% overall yield. In this synthesis, base-mediated phenol ortho-alkylation and piperidine promoted aldol condensation were exploited as key steps. The synthesis was flexible and allowed for the convenient preparation of two analogous natural products glabralide B and denudalide.
- Li, Tian-Ze,Geng, Chang-An,Chen, Ji-Jun
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supporting information
(2019/08/27)
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- Synthesis, functionalization, and isolation of planar-chiral pillar[5]arenes with bulky substituents using a chiral derivatization agent
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Bulky perneopentyloxy-pillar[5]arene (Pillar-1) was synthesized and its conformational mobility was investigated using variable-temperature 1H NMR spectroscopy. The host-guest interactions between Pillar-1 and n-octyltrimethylammonium hexafluorophosphate (OMA) were investigated, and the formation of a 1:1 complex was revealed via1H NMR. Planar-chiral isomers were synthesized via the reaction of a hydroxy-functionalized pillar[5]arene with chiral derivatization agent (S)-(+)-MTPA-Cl. The (Sp, R)-and (Rp, R)-forms of the pillar[5]arene diastereomers were isolated by HPLC, and their structures were analyzed by 19F NMR. HPLC measurements indicated that racemization did not take place at 40 °C for 72 h.
- Al-Azemi, Talal F.,Vinodh, Mickey,Alipour, Fatemeh H.,Mohamod, Abdirahman A.
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p. 23295 - 23301
(2019/08/12)
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- Method of removing protective groups of olefins under catalytic action of nickel
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The invention relates to a method of removing protective groups of olefins under the catalytic action of nickel. The method comprises following steps: dissolving olefin containing compounds into an organic solvent, carrying out reactions in the presence of a catalyst, organic ligands, bis(pinacolato)diboron, alkalis, alcohols, and water, wherein the catalyst contains nickel; after reactions, adding excess hydrochloric acid solution (1M) to adjust the pH to the acidic region, stirring the solution until the solution becomes clear; adding water and ethyl acetate to carry out extraction; washing the organic phase by saturated brine, drying the organic phase by anhydrous sodium sulfate, carrying out condensation, and adopting a 200-300 mesh silica gel column to carry out chromatographic separation to obtain compounds that contains alcohols or phenol. The provide method has the advantages that the adopted chemical reagents are common, the primary alkyl halide protective groups of olefins can be removed efficiently, and the method has a good application prospect in the field of organic synthesis and good industrial potential.
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Paragraph 0204-0208
(2019/10/04)
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- METHOD FOR SYNTHESIZING PHENOL USING METAL CATALYST
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The present invention relates to a method for synthesizing phenol using a metal catalyst and, more specifically, to a method for preparing phenol, which is a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst. According to the present invention, phenol, as a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst, can be synthesized with high yield. Also, various phenols having substituents can be synthesized.COPYRIGHT KIPO 2017
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Paragraph 0058; 0060
(2017/10/26)
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- Bismuth trichloride–mediated cleavage of phenolic methoxymethyl ethers
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A simple and efficient method for removal of phenolic methoxymethyl ethers in the presence of 30?mol% of bismuth trichloride in acetonitrile/water is described. Notable features of the cleavage protocol entail use of an ecofriendly bismuth reagent, ease of handling, low cost, operational simplicity, and good functional group compatibility. A number of structurally varied phenolic methoxymethyl ethers were cleaved in good to excellent yields.
- Obaro-Best, Oghale,Reed, Jack,Norfadilah, Alya A. F. B.,Monahan, Ryan,Sunasee, Rajesh
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supporting information
p. 586 - 593
(2016/06/08)
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- Reaction of 1,2-difunctionalized ethanes with aryl iodides in copper-catalyzed cross-coupling: Application to synthesis of phenols
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A series of 1,2-difunctionalized ethanes, such as ethylene glycol, 2-aminoethanol, 1,2-diaminoethane, 2-dimethylaminoethanol N',N'-dimethylethane-1,2-diamine, were investigated to test the reactivity with aryl iodides in the presence of copper catalysts. Under the reaction conditions, they produce the various Cheteroatom cross-coupled products. Interestingly, ethylene glycol and 2-dimethylaminoethanol afforded mainly the phenolic compounds while the others produced different cross-coupled products. Although ethylene glycol and 2-dimethylaminoethanol resulted in the same product, their behaviors in the reaction were quite different: ethylene glycol appears to mostly act as the ligand and 2-dimethylaminoethanol appears to serve as both the ligand and reactant. This finding led to a copper-catalyzed synthesis of phenols using either ethylene glycol or 2-dimethylaminoethanol, which can be applied to a variety of aryl iodides, providing an alternative synthetic route to phenols.
- Kim, Jihye,Battsengel, Oyunsaikhan,Liu, Yajun,Chae, Junghyun
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supporting information
p. 2833 - 2840
(2016/02/05)
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- Rapid and green synthesis of phenols catalyzed by a deep eutectic mixture based on fluorinated alcohol in water
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A new deep eutectic mixture based on choline chloride and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was prepared and was found to be effective for the rapid transformation of aryl/heteroaryl boronic acids to the corresponding phenols in water using hydrogen peroxide as the oxidant. Broad substrate compatibility, metal- and additive-free conditions as well as reusability of the catalyst made this procedure more environmentally benign.
- Wang, Liang,Dai, Dong-Yan,Chen, Qun,He, Ming-Yang
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- Facile conversion of para-benzoquinones to para-alkoxyphenols with primary/secondary alcohols and amberlyst-15: A process showing novel reducing property of such alcohols
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A new efficient methodology has been developed for the synthesis of para-alkoxyphenols, an important group of anti-melanoma compounds, by heating alcoholic solutions of para-benzoquinones in the presence of amberlyst-15. The most notable feature here is the behaviour of the used primary or secondary alcohol as an effective reducing agent.
- Mondal, Rina,Guha, Chayan,Mallik, Asok K.
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supporting information
p. 86 - 89
(2014/01/06)
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- Highly practical iron-catalyzed C-O cleavage reactions
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Facile iron-catalyzed cleavage of various allyl, cinnamyl and benzyl C-O linkages has been effected in the presence of ethylmagnesium chloride. The protocol is operationally simple (xylene-THF, r.t., 1 h), requires low catalyst loading (1 mol% FeCl2) and tolerates halides, esters, amines, ethers and olefins. The allyl moiety is converted to volatile hydrocarbons which renders laborious product separation unnecessary.
- Gaertner, Dominik,Konnerth, Hannelore,Von Wangelin, Axel Jacobi
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p. 2541 - 2545
(2013/09/24)
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- Base mediated deprotection strategies for trifluoroethyl (TFE) ethers, a new alcohol protecting group
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A trifluoroethyl (TFE) ether is specifically introduced as a protecting group in organic chemistry. Its first strategic application and removal in the total synthesis of vinigrol is discussed. Two lithium base mediated deprotection strategies for its removal are presented in this Letter. In one deprotection approach, the trifluoroethyl ether is converted to a difluorovinyl ether and then catalytically cleaved using osmium tetraoxide, while in the second approach a difluorovinyl anion is formed and trapped with an electrophilic oxygen reagent (MoOPH) to form a labile difluoroacetate. To further aid the reader, a summary of approaches for forming trifluoroethyl ethers is included as well as a discussion of alternate deprotection strategies.
- Yang, Qingliang,Njardarson, Jon T.
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supporting information
p. 7080 - 7082
(2013/12/04)
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- Copper(II)-catalyzed hydroxylation of aryl halides using glycolic acid as a ligand
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Copper(II)-catalyzed hydroxylation of aryl halides has been developed to afford functionalized phenols. The protocol utilizes the reagent combination of Cu(OH)2, glycolic acid, and NaOH in aqueous DMSO, all of which are cheap, readily available, and easily removable after the reaction. A broad range of aryl iodides and activated aryl bromides were transformed into the corresponding phenols in excellent yields. Moreover, it has been shown that C-O(alkyl)-coupled product, instead of phenol, can be predominantly formed under similar reaction conditions.
- Xiao, Yan,Xu, Yongnan,Cheon, Hwan-Sung,Chae, Junghyun
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p. 5804 - 5809
(2013/07/25)
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- Pd/C-mediated depropargylation of propargyl ethers/amines in water
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Propargyl ethers and amines are effectively depropargylated to the parent alcohols or amines via a C-O/C-N bond cleavage catalyzed by 10% Pd/C in water. This simple, facile, and inexpensive methodology could be utilized for the selective removal of propargyl groups from a variety of aryl ethers and amines.
- Rambabu,Bhavani,Swamy, Nalivela Kumara,Basaveswara Rao,Pal, Manojit
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p. 1169 - 1173
(2013/04/10)
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- Oxidation of organotrifluoroborates via oxone
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A method for the oxidation of organotrifluoroborates using Oxone was developed. A variety of aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates were converted into the corresponding oxidized products in excellent yields. This method proved to be tolerant of a broad range of functional groups, and in secondary alkyl substrates it was demonstrated to be completely stereospecific.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 623 - 630
(2011/03/20)
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- Ti(O-i-Pr)4/Me3SiCl/Mg-mediated reductive cleavage of sulfonamides and sulfonates to amines and alcohols
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A low-valent titanium generated in situ from Ti(O-i-Pr)4, Me3SiCl, and Mg powder in THF reacted with aryl- and alkyl-sulfonamides of aryl and alkyl amines in a reductive N-S/S-O/S-C bond cleaving pathway to provide the corresponding amines and hydrocarbons (and thiols) derived from the sulfonyl moiety. The reagent could also cleave sulfonates to the corresponding alcohols.
- Shohji, Noriaki,Kawaji, Tsuyoshi,Okamoto, Sentaro
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supporting information; experimental part
p. 2626 - 2629
(2011/07/08)
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- The reaction of α-phenethyl radicals with 1,4-benzoquinone and 2,6-di-tert-butyl-1,4-benzoquinone
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The absolute rate constant for 1,4-benzoquinone (BQ) irreversibly trapping α-phenethyl radicals (3) has been determined as 4.4×106 M-1 s-1 at 43 °C using acyclic cis azoalkane 9c as a radical precursor. These reactants afford the hydroquinone mono ether 4 at 30 °C but a mixture of products at elevated temperature. 2,6-Di-tert-butyl-1,4- benzoquinone (DTBQ) also reacts with 3 but the cyclohexadienone products are thermally labile.
- Engel, Paul S.,Park, Hee Jung,Mo, Hua,Duan, Shaoming
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body text
p. 8805 - 8814
(2011/01/04)
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- The continuous catalytic debenzylation of 1,4-dibenzyloxybenzene with H2 in THF expanded with high pressure CO2
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The continuous debenzylation of 1,4-dibenzyloxybenzene (1a) with H 2 and supported Pd catalysts has been studied in high-pressure CO2 + tetrahydrofuran. A range of parameters and catalysts have been tested, with one of the most successful results giving 86% conversion and 86% selectivity to the monodebenzylated product, 1,4-(benzyloxy)phenol (2a). In the absence of CO2, the reaction was unselective with no formation of 2a. When complete debenzylation was required, the best catalyst was 5% Pd supported on Deloxan APII, giving quantitative yields of hydroquinone (3), the completely debenzylated product, at temperatures as low as 50 °C. This Deloxan-supported catalyst was also substantially active at only 30 °C.
- Akien, Geoffrey R.,Legeay, Jean-Christophe,Wells, Andrew,Poliakoff, Martyn
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experimental part
p. 1202 - 1208
(2011/04/22)
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- Counterattack mode differential acetylative deprotection of phenylmethyl ethers: Applications to solid phase organic reactions
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A counterattack protocol for differential acetylative cleavage of phenylmethyl ether has been developed. The phenylmethyl moiety is liberated as benzyl bromide that is isolated and reused providing advantages in terms of waste minimization/utilization and atom economy. The applicability of this methodology has been extended for solid phase organic reactions with the feasibility of reuse of the solid support.
- Chakraborti, Asit K.,Chankeshwara, Sunay V.
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experimental part
p. 1367 - 1370
(2009/07/04)
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- Instantaneous deprotection of tosylamides and esters with Sml 2/amine/water
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(Chemical Equation Presented) Sml2/amine/water mediates instantaneous cleavage of tosyl amides and tosyl esters. Highly hindered, sensitive and functionalized substrates were successfully deprotected in near quantitative yield.
- Ankner, Tobias,Hilmersson, Goeran
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supporting information; scheme or table
p. 503 - 506
(2009/07/11)
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- Organocatalytic methods for chemoselective O-tert-butoxycarbonylation of phenols and their regeneration from the O-t-Boc derivatives
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(Chemical Equation Presented) Carbon tetrabromide (CBr4) catalyzes O-tert-butoxycarbonylation of functionalized phenols without any side reactions (bromination, addition of CBr3 to a double bond, and formation of symmetrical diaryl carbonates, cyclic carbonates, or carbonic-carbonic anhydrides). The parent phenols are regenerated from the O-t-Boc derivatives by the catalyst system CBr4-PPh3 without affecting other protecting groups (aryl alkyl ether, alkyl ester, and thioacetal) or competitive side reaction such as bromination, nitrene (from NO2) and α,α-dibromoolefine (with CHO/COMe) formation, and transesterification (with CO2Me/Et) taking place.
- Chankeshwara, Sunay V.,Chebolu, Rajesh,Chakraborti, Asit K.
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scheme or table
p. 8615 - 8618
(2009/04/11)
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- High-yielding cleavage of (aryloxy)acetates
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A reliable and high-yielding one-pot sequence for the removal of O-carboxymethyl moieties from phenols is presented. When diethylphosphoryl azide is employed as the azide transfer reagent in the Curtius rearrangement and glycerol in the subsequent hydrolytic workup, the protocol can be reliably applied to a very broad scope of substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Spurg, Anke,Waldvogel, Siegfried R.
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p. 337 - 342
(2008/09/18)
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- Selective cleavage of allyl and propargyl ethers to alcohols catalyzed by Ti(O-i-Pr)4/MXn/Mg
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(Chemical Equation Presented) Allyl and propargyl ethers were effectively deallylated or depropargylated to the parent alcohols via a C-O bond cleavage catalyzed by a low-valent titanium reagent (LVT), Ti(O-i-Pr)4/TMSCI/ Mg or Ti(O-i-Pr)4/MgBr2/Mg, under mild reaction conditions. Differentiation between the allyl and propargyl ethers was achieved by the reaction in the presence of AcOEt as an additive. The reagent also catalyzed intra- and intermolecular cyclotrimerization reactions of alkynes to substituted benzenes.
- Ohkubo, Mutsumi,Mochizuki, Sayaka,Sano, Takeshi,Kawaguchi, Yuuki,Okamoto, Sentaro
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p. 773 - 776
(2007/10/03)
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- Synthesis of ethyl 3-(hydroxyphenoxy)benzyl butylphosphonates as potential antigen 85C inhibitors
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All three isomers of ethyl 3-(hydroxyphenoxy)benzyl butylphosphonates as potential antigen 85C inhibitors were synthesized from 3-bromobenzoic acid using Ullman diaryl ether synthesis combined with benzyl- and trityl protection strategy for the phenol hydroxyl groups.
- Frlan, Rok,Gobec, Stanislav,Kikelj, Danijel
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p. 10698 - 10708
(2008/02/13)
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- Benzyloxy derivatives as MAOB inhibitors
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The invention relates to compounds of the formula and their pharmaceutically acceptable salts wherein R1, R2, R3, R4, R5, n, m, and o are as defined in the specification. The compounds are selective monoamine oxidase β inhibitors and are useful for the treatment and prevention of Alzheimer's disease and senile dementia, as well as other CNS disorders. The invention also relates to processes for preparing such compounds and pharmaceutical compositions containing them.
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Page/Page column 9
(2008/06/13)
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- Palladium charcoal-catalyzed deprotection of O-allylphenols
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Allyl aryl ethers can be easily cleaved by the use of 10% Pd/C under mild and basic conditions. The present reaction would involve a SET process rather than a π-allyl-palladium complex. The scope and limitation of this new deprotective methodology is also described.
- Ishizaki, Miyuki,Yamada, Makoto,Watanabe, Shin-Ichi,Hoshino, Osamu,Nishitani, Kiyoshi,Hayashida, Maiko,Tanaka, Atsuko,Hara, Hiroshi
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p. 7973 - 7981
(2007/10/03)
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- Compound
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There is provided a compound of Formula I 1 wherein each T is independently selected from H, hydrocarbyl, —F—R, and a bond with one of D, E, P or Q, or together with one of P and Q forms a ring; Z is a suitable atom the valency of which is m; D, E and F are each independently of each other an optional linker group, wherein when Z is nitrogen E is other than CH2 and C═O; P, Q and R are independently of each other a ring system; and at least Q comprises a sulphamate group.
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Page/Page column 65
(2008/06/13)
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- Efficient, selective deprotection of aromatic acetates catalyzed by Amberlyst-15 or iodine
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Aromatic acetates were selectively deprotected in the presence of aliphatic acetates to the corresponding phenols in excellent yields using Amberlyst-15 or iodine as catalysts in methanol at room temperature. The first catalyst can be recovered.
- Das, Biswanath,Banerjee, Joydeep,Ramu,Pal, Rammohan,Ravindranath,Ramesh
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p. 5465 - 5468
(2007/10/03)
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- A mild chemoselective and rapid regeneration of alcohols from O-allyl ethers by LiCl/NaBH4
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An efficient chemoselective cleavage of O-allyl protected is developed employing LiCl/NaBH4.
- RajaRam,Purushothama Chary,Salahuddin,Iyengar
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p. 133 - 137
(2007/10/03)
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- A novel, simple and rapid regeneration of alcohols from their allylic ethers using NaCNBH3/TMSCl
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A Novel, Simple and efficient method for the regeneration of alcohols from their allylic ethers using NaCNBH3/TMSCl is described.
- Venkat Rao,Subbash Reddy,Hari Mohan,Iyengar
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p. 3565 - 3568
(2007/10/03)
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