- Discovery of Novel UDP- N-Acetylglucosamine Acyltransferase (LpxA) Inhibitors with Activity against Pseudomonas aeruginosa
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This study describes a novel series of UDP-N-acetylglucosamine acyltransferase (LpxA) inhibitors that was identified through affinity-mediated selection from a DNA-encoded compound library. The original hit was a selective inhibitor of Pseudomonas aeruginosa LpxA with no activity against Escherichia coli LpxA. The biochemical potency of the series was optimized through an X-ray crystallography-supported medicinal chemistry program, resulting in compounds with nanomolar activity against P. aeruginosa LpxA (best half-maximal inhibitory concentration (IC50) 20 μM and MIC > 128 μg/mL). The mode of action of analogues was confirmed through genetic analyses. As expected, compounds were active against multidrug-resistant isolates. Further optimization of pharmacokinetics is needed before efficacy studies in mouse infection models can be attempted. To our knowledge, this is the first reported LpxA inhibitor series with selective activity against P. aeruginosa.
- Andersen, Ole A.,Barbeau, Olivier R.,Barker, John,Cain, Ricky,Centrella, Paolo A.,Clark, Matthew A.,Compper, Christel,Corbett, David,Cuozzo, John W.,Dejob, Magali,Dejonge, Boudewijn L. M.,Deng, Boer,Dickie, Anthony P.,Dorali, Alain,Etheridge, Donnya,Evans, Sian,Faulkner, Adele,Gadouleau, Elise,Gorman, Timothy,Haase, Denes,Holbrow-Wilshaw, Maisie,Hunt, Avery,Keefe, Anthony D.,Krulle, Thomas,Li, Xianfu,Lumley, Christopher,Mertins, Barbara,Napier, Spencer,Odedra, Rajesh,Papadopoulos, Kostas,Parkes, Alastair L.,Roumpelakis, Vasileios,Ryan, M. Dominic,Sanzone, Angelo,Sigel, Eric A.,Southey, Michelle,Soutter, Holly T.,Spear, Kate,Stein, Daniel B.,Thommes, Pia,Trimby, Emily,Troast, Dawn M.,Williams, Jennifer,Zahn, Michael,Zhang, Ying
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p. 14377 - 14425
(2021/10/25)
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- Selective C-H Iodination of (Hetero)arenes
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Iodoarenes are versatile intermediates and common synthetic targets in organic synthesis. Here, we present a strategy for selective C-H iodination of (hetero)arenes with a broad functional group tolerance. We demonstrate the utility and differentiation to other iodination methods of supposed sulfonyl hypoiodites for a set of carboarenes and heteroarenes.
- Tanwar, Lalita,B?rgel, Jonas,Lehmann, Johannes,Ritter, Tobias
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supporting information
p. 5024 - 5027
(2021/06/30)
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- Biomimetic carbene cascades enabled imine derivative migration from carbene -bearing thiocarbamates
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Inspired by the body circulation of Omeprazole (irreversible proton pump inhibitor), we disclose the carbene-triggered cascades for the synthesis of 2-aminobenzofuran derivatives from N-sulfonyl-1,2,3-triazoles or benzothioazole-bearing thiocarbamates, which represents an unprecedented imine derivative migration process. Furthermore, the desulfurizing reagent-free Barton-Kellogg-type reactions starting from N-sulfonyl-1,2,3-triazoles have also been achieved for the first time, and elemental sulfur is confirmed as a byproduct during this transformation. Both experimental data and DFT calculations further thoroughly explained the unique reactivity.
- Li, Xue,Chen, Haohua,Xuan, Qingqing,Mai, Shaoyu,Lan, Yu,Song, Qiuling
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supporting information
p. 3518 - 3523
(2021/05/29)
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- Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor
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Novel approaches for N- and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KOtBu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KOtBu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.
- Heredia, Micaela D.,Guerra, Walter D.,Barolo, Silvia M.,Fornasier, Santiago J.,Rossi, Roberto A.,Budén, Mariá E.
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supporting information
p. 13481 - 13494
(2020/12/15)
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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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- AN IMPROVED ONE POT, ONE STEP PROCESS FOR THE HALOGENATION OF AROMATICS USING SOLID ACID CATALYSTS
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The present invention disclosed an improved one pot, one step process for halogenation of compound of formula (II) to afford corresponding halogenated compound of formula (I) having improved yield and increased selectivity under very mild conditions.
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-
Page/Page column 0047; 0048
(2019/04/18)
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- A Convenient Palladium-Catalyzed Carbonylative Synthesis of (E)-3-Benzylidenechroman-4-ones
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A convenient palladium-catalyzed carbonylation reaction for the efficient synthesis of (E)-3-benzylidenechroman-4-ones has been developed. Using TFBen as a solid CO source, a range of substituted (E)-3-benzylidenechroman-4-ones were prepared in moderate to good yields with 2-iodophenols and allyl chlorides as the substrates. Additionally, substituted quinolin-4(1H)-ones can also be obtained with 2-iodoaniline as the starting material.
- Wang, Wei-Feng,Peng, Jin-Bao,Qi, Xinxin,Ying, Jun,Wu, Xiao-Feng
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supporting information
p. 3521 - 3524
(2019/02/14)
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- Synthesis of Ti-Al binary oxides and their catalytic application for C-H halogenation of phenols, aldehydes and ketones
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Traditional C–H halogenation of organic compounds often requires corrosive agent or harsh condition, and current researches are focused on the use of noble metals as catalyst. In order to give an efficient, benign, activity-adjustable and cost-effective system for halogenation, a series of Ti-Al mixed oxides are prepared as catalyst through sol-gel in this work. Characterizations reveal all catalysts contain more aluminum than titanium, but preparative conditions affect their composition and crystallinity. Monitoring of particle size, zeta potential and UV–vis of preparative solution reveals that formation of catalyst colloids undergoes chemical reaction, affecting catalyst morphology. In halogenation, all catalysts show moderate to high activities, copper chloride proves to be an effective halogen source rather than sodium chloride. The chlorination and bromination are better than iodization, phenol and ketone appear to be more appropriate substrates than aldehyde. Additionally, oxide backbone of catalyst is more durable than its organic components during recycling. This study may provide new catalytic materials for progress of C–H activation.
- Su, Peigen,Fan, Chao,Yu, Heng,Wang, Wanqin,Jia, Xin,Rao, Qifan,Fu, Chenxi,Zhang, Donghua,Huang, Benhua,Pan, Cheng,Zheng, Aqun,Sun, Yang
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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.
- -
-
Paragraph 0150-0153
(2019/10/04)
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- Electrochemical Hydroxylation of Arenes Catalyzed by a Keggin Polyoxometalate with a Cobalt(IV) Heteroatom
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The sustainable, selective direct hydroxylation of arenes, such as benzene to phenol, is an important research challenge. An electrocatalytic transformation using formic acid to oxidize benzene and its halogenated derivatives to selectively yield aryl formates, which are easily hydrolyzed by water to yield the corresponding phenols, is presented. The formylation reaction occurs on a Pt anode in the presence of [CoIIIW12O40]5? as a catalyst and lithium formate as an electrolyte via formation of a formyloxyl radical as the reactive species, which was trapped by a BMPO spin trap and identified by EPR. Hydrogen was formed at the Pt cathode. The sum transformation is ArH+H2O→ArOH+H2. Non-optimized reaction conditions showed a Faradaic efficiency of 75 % and selective formation of the mono-oxidized product in a 35 % yield. Decomposition of formic acid into CO2 and H2 is a side-reaction.
- Khenkin, Alexander M.,Somekh, Miriam,Carmieli, Raanan,Neumann, Ronny
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supporting information
p. 5403 - 5407
(2018/04/19)
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- 8,10,12 as nanoreactors for non-enzymatic introduction of: Ortho, meta or para -hydroxyl groups to aromatic molecules
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Traditional electrophilic bromination follows long established "rules": electron-withdrawing substituents cause bromination selective for meta positions, whereas electron-donating substituents favor ortho and para bromination. In contrast, in the [PhSiO1.5]8,10,12 silsesquioxanes, the cages act as bulky, electron withdrawing groups equivalent to CF3; yet bromination under mild conditions, without a catalyst, greatly favors ortho substitution. Surprisingly, ICl iodination without a catalyst favors (>90%) para substitution [p-IC6H4SiO1.5]8,10,12. Finally, nitration and Friedel-Crafts acylation and sulfonylation are highly meta selective, >80%. In principle, the two halogenation formats coupled with the traditional electrophilic reactions provide selective functionalization at each position on the aromatic ring. Furthermore, halogenation serves as a starting point for the synthesis of two structural isomers of practical utility, i.e. in drug prospecting. The o-bromo and p-iodo compounds are easily modified by catalytic cross-coupling to append diverse functional groups. Thereafter, F-/H2O2 treatment cleaves the Si-C bonds replacing Si with OH. This represents a rare opportunity to introduce hydroxyl groups to aromatic rings, a process not easily accomplished using traditional organic synthesis methods. The as-produced phenol provides additional opportunities for modification. Each cage can be considered a nanoreactor generating 8-12 product molecules. Examples given include syntheses of 4,2′-R,OH-stilbenes and 4,4′-R,OH-stilbenes (R = Me, CN). Unoptimized cleavage of the Br/I derivatives yields 55-85% phenol. Unoptimized cleavage of the stilbene derivatives yields 35-40% (3-5 equivalents of phenol) in the preliminary studies presented here. In contrast, meta R-phenol yields are 80% (7-10 mol per cage).
- Bahrami, Mozhgan,Zhang, Xingwen,Ehsani, Morteza,Jahani, Yousef,Laine, Richard M.
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supporting information
p. 8797 - 8808
(2017/07/22)
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- Synthesis of 8-azaprotosappanin A derivatives via intramolecular palladium-catalyzed ortho C-H activation/C-C cyclization and their antibacterial activity
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A novel synthetic protocol for the construction of eight-membered heterocycles by intramolecular palladium-catalyzed ortho C-H activation/C-C cyclization was proposed. With protosappanin A as the lead compound, 25 derivatives of 8-azaprotosappanin A were prepared in good yields by this protocol. Besides, a plausible reaction mechanism of the intramolecular cyclization was proposed. This strategy could be widely used in the synthesis of some natural products and drugs with large heterocycles due to the fast reaction rate and the mild conditions. In vitro antimicrobial activities of the synthesized compounds were assessed against the strains of Gram-positive bacteria and linezolid and ciprofloxacin were selected as the standard drugs. Some of the synthesized compounds were found to have excellent antibacterial activities.
- Zhou, Xuan,Fu, Wanyong,Jiang, Hongshuo,Wang, Chenglong,Ju, Chao,Chu, Wenyi,Sun, Zhizhong
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supporting information
p. 1956 - 1960
(2017/03/11)
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- Catalytic Reductive ortho-C-H Silylation of Phenols with Traceless, Versatile Acetal Directing Groups and Synthetic Applications of Dioxasilines
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A new, highly selective, bond functionalization strategy, achieved via relay of two transition metal catalysts and the use of traceless acetal directing groups, has been employed to provide facile formation of C-Si bonds and concomitant functionalization of a silicon group in a single vessel. Specifically, this approach involves the relay of Ir-catalyzed hydrosilylation of inexpensive and readily available phenyl acetates, exploiting disubstituted silyl synthons to afford silyl acetals and Rh-catalyzed ortho-C-H silylation to provide dioxasilines. A subsequent nucleophilic addition to silicon removes the acetal directing groups and directly provides unmasked phenol products and, thus, useful functional groups at silicon achieved in a single vessel. This traceless acetal directing group strategy for catalytic ortho-C-H silylation of phenols was also successfully applied to preparation of multisubstituted arenes. Remarkably, a new formal α-chloroacetyl directing group has been developed that allows catalytic reductive C-H silylation of sterically hindered phenols. In particular, this new method permits access to highly versatile and nicely differentiated 1,2,3-trisubstituted arenes that are difficult to access by other catalytic routes. In addition, the resulting dioxasilines can serve as chromatographically stable halosilane equivalents, which allow not only removal of acetal directing groups but also introduce useful functional groups leading to silicon-bridged biaryls. We demonstrated that this catalytic C-H bond silylation strategy has powerful synthetic potential by creating direct applications of dioxasilines to other important transformations, examples of which include aryne chemistry, Au-catalyzed direct arylation, sequential orthogonal cross-couplings, and late-stage silylation of phenolic bioactive molecules and BINOL scaffolds.
- Hua, Yuanda,Asgari, Parham,Avullala, Thirupataiah,Jeon, Junha
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p. 7982 - 7991
(2016/07/07)
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- Total synthesis of protosappanin A and its derivatives via palladium catalyzed ortho C-H activation/C-C cyclization under microwave irradiation
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A total synthesis method for protosappanin A, which is a complex natural product with many biological activities, was developed with 6 linear steps. Dibenzo[b,d]oxepinones as the key intermediates of the synthetic route were prepared by a palladium-catalyzed ortho C-H activation/C-C cyclization under microwave irradiation. 25 derivatives of protosappanin A were obtained.
- Liu, Jiaqi,Zhou, Xuan,Wang, Chenglong,Fu, Wanyong,Chu, Wenyi,Sun, Zhizhong
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supporting information
p. 5152 - 5155
(2016/05/02)
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- Organic hypervalent iodine(III) catalyzed ipso-hydroxylation of aryl- and alkylboronic acids/esters
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An organo-hypervalent iodine(III) catalyzed highly efficient methodology for ipso-hydroxylation of diversely functionalized aryl- and alkylboronic acids/esters has been developed using NaIO4 as a co-oxidant. This protocol is also applicable to N-heterocyclic boronic acids and esters. Further mechanistic studies revealed that the organoboronic acid (an electron demanding moiety) is acting as a nucleophile in the presence of hypervalent iodine for hydroxylation reactions. In summary, this is the first Letter of a generalized route for organic hypervalent iodine(III) catalyzed hydroxylation of organoboronic compounds.
- Chatterjee, Nachiketa,Goswami, Avijit
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supporting information
p. 1524 - 1527
(2015/03/14)
-
- O-arylation of iodophenols with 2-fluorobenzaldehyde under microwave conditions
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The arylation of 4-iodo-, 2-iodo- and 3-iodophenols with 2-fluorobenzaldehyde may be carried out in the presence of K2CO 3 in DMF as the solvent under microwave conditions. The arylation of 4-iodophenole was promoted by the use of triethylbenzylammonium chloride (TEBAC) as the phase transfer catalyst. In the other model reactions, the use of TEBAC was harmful. By-products formed by isomerization and disproportionation were also detected.
- Balint, Erika,Kallai, Monika,Kovacs, Orsolya,Boelcskei, Hedvig,Keglevich, Gyoergy
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p. 114 - 120
(2014/01/06)
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- Hydroxylation of aryl- and alkylboronic acids/esters mediated by iodobenzene diacetate - An avenue for using organoboronic acids/esters as nucleophiles for hydroxylation reactions
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A metal free, mild, and highly efficient methodology for ipso-hydroxylation of diversely functionalized aryl- and alkylboronic acids/esters mediated by iodobenzene diacetate (DAIB) under ambient temperature has been developed. This protocol is also applicable to N-heterocyclic boronic acids and esters. In the course of understanding the mechanism of this protocol, it is anticipated that organoboronic acid/ester, even being an electron demanding moiety, is acting as a nucleophile in the presence of DAIB for the hydroxylation reaction.
- Chatterjee, Nachiketa,Chowdhury, Hrishikesh,Sneh, Kumar,Goswami, Avijit
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supporting information
p. 172 - 174
(2015/02/02)
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- Benzoquinone-promoted aerobic oxidative hydroxylation of arylboronic acids in water
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A general and efficient aerobic oxidative hydroxylation of arylboronic acids promoted by benzoquinone in water was realized, and provided phenols in 72-95% yields for 20 examples. The main advantages of this protocol are the use of water as solvent in the presence of a catalytic amount of benzoquinone, and metal-free conditions. Georg Thieme Verlag KG Stuttgart · New York.
- Cheng, Guolin,Zeng, Xiaobao,Cui, Xiuling
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p. 295 - 300
(2014/02/14)
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- Regioselective o-hydroxylation of monosubstituted benzenes by P450 BM3
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Dream come true: A new monooxygenase catalyst shows excellent activity for the hydroxylation of halogenated benzenes, anisole, and toluene with almost complete ortho regioselectivity (see scheme; R=F, Cl, Br, I, CH3, OCH3). The substrates were hydroxylated at room temperature in water without cosolvent using molecular oxygen as oxidant. Copyright
- Dennig, Alexander,Luelsdorf, Nina,Liu, Haifeng,Schwaneberg, Ulrich
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p. 8459 - 8462
(2013/09/02)
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- Zinc triflate: A mild and efficient catalyst for deprotection of tetrahydropyranyl ethers
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Treatment of tetrahydropyranyl (THP) ethers with zinc triflate in methanol provides a simple and efficient process for deprotection of these ethers and the parent alcohols are obtained in excellent yields.
- Srinivasulu,Satyanarayana,Ravi Kumar
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p. 2419 - 2422
(2014/03/21)
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- Identification of malate dehydrogenase 2 as a target protein of the HIF-1 inhibitor LW6 using chemical probes
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Tracking the target: To identify a protein that binds directly to the HIF-1α inhibitor LW6, a series of new chemical probes were synthesized with a clickable tag and/or a photoactivatable moiety. LW6 was found to be localized to the mitochondria (see picture) and MDH2 was identified as a target protein of LW6. These results indicate that the HIF-1α inhibitory activity of LW6 is a consequence of MDH2 suppression. Copyright
- Lee, Kyeong,Ban, Hyun Seung,Naik, Ravi,Hong, Ye Seul,Son, Seohyun,Kim, Bo-Kyung,Xia, Yan,Song, Kyung Bin,Lee, Hong-Sub,Won, Misun
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supporting information
p. 10286 - 10289
(2013/10/21)
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- Synthesis of 1,4-benzoxazepine derivatives via a novel domino aziridine ring-opening and isocyanide-insertion reaction
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A novel and efficient domino process has been developed for the synthesis of 1,4-benzoxazepine derivatives from a range of readily accessible N-tosylaziridines, 2-iodophenols and isocyanides. This process involves the aziridine ring-opening reaction with 2-iodophenol, followed by a palladium-catalyzed isocyanide-insertion reaction. This regioselective and high-yielding transformation could be extended to its application for the synthesis of natural products and biologically interesting heterocycles. Copyright
- Ji, Fei,Lv, Mei-Fang,Yi, Wen-Bin,Cai, Chun
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p. 3401 - 3406
(2013/12/04)
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- Simple and efficient method for deprotection of tetrahydropyranyl ethers by using Silica supported sodium hydrogen sulphate
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Tetrahydropyranyl (THP) ethers have been efficiently and simply deprotected by using Silica supported sodium hydrogen sulphate (NaHSO4-SiO 2) in methanol at room temperature to regenerate the parent alcohols in high yields. Tetrahydropyranyl (THP) ethers have been efficiently and simply deprotected by using silica supported sodium hydrogen sulphate (NaHSO 4-SiO2) in methanol at room temperature to regenerate the parent alcohols in high yields.
- Kumar, K. Ravi,Satyanarayana,Reddy, B. Srinivasa
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experimental part
p. 1189 - 1191
(2012/07/27)
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- A Green protocol for the bromination and iodination of the aromatic compounds using H5IO6/NaBr and H5IO 6/NaI in the water
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Bromination and iodination of the aromatic compounds have efficiently been carried out at room temperature and 70 °C, respectively, in short reaction times using orthoperiodic acid/sodium bromide (1:2) and orthoperiodic acid/sodium iodide (1:2) in water to prepare the corresponding halo compounds with excellent yields.
- Yousefi-Seyf, Jaber,Tajeian, Kazem,Kolvari, Eskandar,Koukabi, Nadiya,Khazaei, Ardeshir,Zolfigol, Mohammad Ali
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p. 2619 - 2622
(2012/10/29)
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- Selectivity enhancement of aromatic halogenation reactions at the micellar interface: Effect of highly ionic media
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Halogenation (iodination and bromination) of various aromatic compounds has been studied in micellar media in order to observe the effect on regioselectivity and conversion of the reaction. The addition of surfactant causes a change in the chemical shifts of the aromatic proton resonance of phenol which proves the orientation of the aromatic compound on the micellar surface. However, increase in ionic strength of the reaction media affects the selectivity of reaction by disturbing this spatial orientation of the aromatic compound in the micelle. Selectivity towards particular isomers is dependent on the concentration of the surfactant. In bromination of chlorobenzene (deactivated aromatic compound) enhancement in selectivity and conversion towards the para isomer has been observed.
- Samant, Bhupesh S.,Bhagwat, Sunil S.
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scheme or table
p. 1039 - 1044
(2012/10/18)
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- Gas-Chromatographic identifi cation of products formed in iodination of methyl phenols by retention indices
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Iodination reaction followed by conversion of iodine-substituted methylphenols to the corresponding trifl uoroacetates was suggested for improving the sensitivity of the gas-chromatographic determination of phenol and its methyl-substituted derivatives (al isomers of mono- and diethylphenols, 2,3,5-, 2,3,6-, and 3,4,5-trimethylphenols) in aqueous media. Acylation products of iodo methylphenols (104 compounds) were identifi ed by linear-logarithmic retention indices on a standard nonpolar polydimethylsiloxane stationary phase, and the pattern of their variation with the number and nature of substituents were characterized. A procedure for identifi cation of methyl-substituted phenols in water in their gas-chromatographic determination with an electron-capture detector was developed. Pleiades Publishing, Ltd., 2012.
- Gruzdev,Kuzivanov,Zenkevich,Kondratenok
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p. 1355 - 1365
(2013/01/15)
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- Base-catalyzed dehydration of 3-substituted benzene cis -1,2-dihydrodiols: Stabilization of a cyclohexadienide anion intermediate by negative aromatic hyperconjugation
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Evidence that a 1,2-dihydroxycyclohexadienide anion is stabilized by aromatic "negative hyperconjugation" is described. It complements an earlier inference of "positive" hyperconjugative aromaticity for the cyclohexadienyl cation. The anion is a reactive intermediate in the dehydration of benzene cis-1,2-dihydrodiol to phenol. Rate constants for 3-substituted benzene cis-dihydrodiols are correlated by σ- values with = 3.2. Solvent isotope effects for the reactions are kH2O/kD 2O = 1.2-1.8. These measurements are consistent with reaction via a carbanion intermediate or a concerted reaction with a "carbanion-like" transition state. These and other experimental results confirm that the reaction proceeds by a stepwise mechanism, with a change in rate-determining step from proton transfer to the loss of hydroxide ion from the intermediate. Hydrogen isotope exchange accompanying dehydration of the parent benzene cis-1,2-dihydrodiol was not found, and thus, the proton transfer step is subject to internal return. A rate constant of ~1011 s-1, corresponding to rotational relaxation of the aqueous solvent, is assigned to loss of hydroxide ion from the intermediate. The rate constant for internal return therefore falls in the range 1011-1012 s -1. From these limiting values and the measured rate constant for hydroxide-catalyzed dehydration, a pKa of 30.8 ± 0.5 was determined for formation of the anion. Although loss of hydroxide ion is hugely exothermic, a concerted reaction is not enforced by the instability of the intermediate. Stabilization by negative hyperconjugation is proposed for 1,2-dihydroxycyclohexadienide and similar anions, and this proposal is supported by additional experimental evidence and by computational results, including evidence for a diatropic ("aromatic") ring current in 3,3-difluorocyclohexadienyl anion.
- Kudavalli, Jaya Satyanarayana,Rao, S. Nagaraja,More Oferrall, Rory A.,Bean, David E.,Fowler, Patrick W.,Sharma, Narain D.,Boyd, Derek R.,Kamerlin, Shina Caroline Lynn,Keeffe, James R.,Gronert, Scott
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supporting information
p. 14056 - 14069,14
(2020/08/31)
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- Catalysis by Amberlite IR-120 resin: A rapid and green method for the synthesis of phenols from arylboronic acids under metal, ligand, and base-free conditions
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A clean process has been developed for the ipso-hydroxylation of aryl and heteroaryl boronic acids to the corresponding phenols using commercially available and recyclable Amberlite IR-120 resin and aqueous hydrogen peroxide as an oxidizing agent. The ion-exchange sulfonic acid resin catalyst could be readily recycled by filtration and directly reused at least four times without any significant loss of activity.
- Mulakayala, Naveen,Ismail,Kumar, Kottur Mohan,Rapolu, Rajesh Kumar,Kandagatla, Bhaskar,Rao, Pallavi,Oruganti, Srinivas,Pal, Manojit
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supporting information
p. 6004 - 6007,4
(2020/07/31)
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- Iodination of anilines and phenols with 18-crown-6 supported ICl 2-
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A highly crystalline iodinating reagent, {[K·18-C-6]ICl 2}n, was synthesized in high yield (93%). The trihalide is supported by an 18-crown-6 macrocycle and forms a coordination polymer in the solid state. This reagent iodinates anilines and phenols efficiently under mild conditions. Controlled mono-iodination with anilines was easily achieved while poly-iodination was observed with phenols.
- Mbatia, Hannah W.,Ulloa, Olbelina A.,Kennedy, Daniel P.,Incarvito, Christopher D.,Burdette, Shawn C.
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experimental part
p. 2987 - 2991
(2011/06/16)
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- Green and efficient method for the iodination of phenols in water
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In this article, green conversion of phenols to the corresponding iodide derivatives is reported. The reactions were conducted in water, using potassium iodide as the source of iodine and potassium ferrate as the oxidizing agent. The selected phenols were successfully iodinated in good to excellent yields in mild and non-toxic reaction conditions. Copyright Taylor & Francis Group, LLC.
- Tajik, Hassan,Dadras, Akbar,Hosseini, Abolfazl
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experimental part
p. 258 - 261
(2011/06/26)
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- Efficient iodination of aromatic compounds using potassium ferrate supported on montmorillonite
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Potassium ferrate impregnated on montmorillonite is a mild, cheap, and non-toxic reagent for the iodination of phenols, including naphthol, aromatic amines, and heterocyclic substrates in fair to excellent yields by a simple isolation procedure.
- Keipour, Hoda,Khalilzadeh, Mohammad A.,Mohtat, Bita,Hosseini, Abolfazl,Zareyee, Daryoush
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experimental part
p. 1427 - 1430
(2012/06/01)
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- Synthetic applications of the nickel-catalyzed cyclization of alkynes combined with addition reactions in a domino process
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Carbonickelations of alkynes and functionalization of the resulting vinylnickel moiety have been performed efficiently in a nickel-catalyzed domino cyclization-condensation process. This reaction, which does not require the preparation of any other organometallic reagent, proceeds only by exo-dig cyclization. This convenient and mild method constitutes a one-pot synthesis of substituted dihydrobenzofurans, chromans, isochromans, indoles, or indanes. Theses valuable products are generally obtained in good yields and high stereoselectivity. They are shown to be useful synthons for rapid access to functionalized polycyclic skeletons. Yes nickel can! Carbonickelation of alkynes and functionalization of the resulting vinylnickel moiety occurs efficiently. Overall, a domino cyclization-condensation process propagated by substoichiometric nickel catalysis takes place (see scheme). This one-pot synthesis provides substituted polyheterocyclic compounds in good yields and high stereoselectivity.
- Durandetti, Muriel,Hardou, Lucie,Lhermet, Rudy,Rouen, Mathieu,Maddaluno, Jacques
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supporting information; experimental part
p. 12773 - 12783
(2011/12/04)
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- Regioselective iodination of chlorinated aromatic compounds using silver salts
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The iodination of chlorinated aromatic compounds using Ag 2SO4/I2, AgSbF6/I2, AgBF4/I2, and AgPF6/I2 offers access to iodoarenes that are valuable intermediates in organic synthesis. Specifically, iodination of phenols, anisoles, and anilines with a 3,5-dichloro substitution pattern preferentially yielded the ortho, para, and para iodinated product, respectively. In the case of chlorobenzene and 3-chlorotoluene, AgSbF6/I2, AgBF4/I2, and AgPF 6/I2, but not Ag2SO4/I2, selectively introduced the iodine in para position to the chlorine substituent.
- Joshi, Sudhir N.,Vyas, Sandhya M.,Wu, Huimin,Duffel, Michael W.,Parkin, Sean,Lehmler, Hans-Joachim
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experimental part
p. 7461 - 7469
(2011/10/10)
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- Direct green iodination of phenol over solid acids
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Examination of several solid acid catalysts of different nature (acid resins, zeolites, mixed oxides, Nb-oxide, and Nb-phosphate) was performed for the direct iodination reaction of phenol by using molecular iodine. The experiments were carried out in mil
- Carniti, Paolo,Colonna, Stefano,Gervasini, Antonella
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scheme or table
p. 55 - 62
(2010/09/05)
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- Efficient and selective iodination of phenols promoted by iodine and hydrogen peroxide in water
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A simple and selective reaction for the preparation of iodinated phenols was developed and phenol derivatives containing electron withdrawing groups were iodinated in very good yields under relatively mild conditions.
- Gallo, Rafael D.C.,Gebara, Karimi S.,Muzzi, Rozanna M.,Raminelli, Cristiano
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experimental part
p. 770 - 774
(2010/08/13)
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- METHOD OF PRODUCING IODIZING AGENT, AND METHOD OF PRODUCING AROMATIC IODINE COMPOUND
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A method of the present invention, for producing an iodizing agent, includes the step of electrolyzing iodine molecules in a solution by using an acid as a supporting electrolyte. This realizes (i) a method of producing an iodine cation suitable for use as an iodizing agent that does not require a sophisticated separation operation after iodizing reaction is completed, and (ii) an electrolyte used in the method. Further, a method of the present invention, for producing an aromatic iodine compound, includes the step of causing an iodizing agent, and an aromatic compound whose nucleus has one or more substituent groups and two or more hydrogen atoms, to react with each other under the presence of a certain ether compound. This realizes such a method of producing an aromatic iodine compound that position selectivity in iodizing reaction of an aromatic compound is improved.
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Page/Page column 10
(2010/05/13)
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- Regiospecific oxyhalogenation of aromatics over SBA-15-supported nanoparticle group IV-VI metal oxides
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TiOx, VOx, MoOx and WOx supported on SBA-15 exhibit efficient catalytic activity for oxyhalogenation of aromatics with the H2O2-halide ion system. Unlike the hitherto known solid catalysts, these reusable catalysts yield the para-halogenated product with 100% selectivity at 298 K and moderate acidic pH (3-5). The catalytic activity was enhanced by five orders of magnitude when supported on SBA-15. Springer Science+Business Media, LLC 2010.
- Saikia,Rajesh,Srinivas,Ratnasamy
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scheme or table
p. 190 - 201
(2010/11/05)
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- Ecofriendly iodination of activated aromatics and coumarins using potassium iodide and ammonium peroxodisulfate
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An environmentally benign protocol for the iodination of activated aromatics, such as phenols, anilines, and hydroxycou-marins, using inexpensive commercially available potassium iodide and ammonium peroxodisulfate (1:2.5 molar equivalents per mole of substrate) in aqueous methanol (MeOH-H 2O, 6:1) at room temperature has been developed. The protocol provides for ortho-selective monoiodination as the predominant product without added acid and it is compatible with a number of common oxidizible functional groups, such as formyl, benzylic C-H, aromatic amines and hydroxymethyl. Good to acceptable yields of monoiodinated products in acceptable reaction times and exclusive ortho-iodination for 7-hydroxycoumarins, despite the presence of vinylogous electronrich C3, are some of the key advantageous features of the method. Georg Thieme Verlag Stuttgart.
- Ganguly, Nemai C.,Barik, Sujoy Kumar,Dutta, Sanjoy
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experimental part
p. 1467 - 1472
(2010/09/16)
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- Identification of a boron-containing intermediate in the boron tribromide mediated aryl propargyl ether cleavage reaction
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An alternate reaction mechanism for the boron tribromide mediated deprotection of aryl propargyl ethers based on the isolation of a key boron-containing byproduct is proposed. On the basis of the new mechanistic insight, we discovered that HBBr2 · SMe2 can also be used for cleaving aryl propargyl ethers.
- Yao, Min-Liang,Reddy, Marepally Srinivasa,Zeng, Wenbin,Hall, Kelly,Walflsh, Ingrid,Kabalka, George W.
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supporting information; experimental part
p. 1385 - 1387
(2009/07/04)
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- Regioselective iodination of phenol and analogues using N-iodosuccinimide and p-toluenesulfonic acid
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Mild and highly regioselective monoiodination of phenol and analogues is achieved in high to excellent yields at room temperature with a combination of stoichiometric p-toluenesulfonic acid and N-iodosuccinimide.
- Bovonsombat, Pakorn,Leykajarakul, Juthamard,Khan, Chiraphorn,Pla-on, Kawin,Krause, Michael M.,Khanthapura, Pratheep,Ali, Rameez,Doowa, Niran
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scheme or table
p. 2664 - 2667
(2009/08/09)
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- Iodination of aromatic compounds using potassium iodide and hydrogen peroxide
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A simple, efficient, regioselective, and ecofriendly method for oxyiodination of aromatic compounds is presented. In this method, the electrophilic substitutions of iodine generated in situ from KI as an iodine source and hydrogen peroxide as an oxygen source have been employed without any catalyst/mineral acid for the first time. Copyright Taylor & Francis Group, LLC.
- Reddy, K. Suresh Kumar,Narender,Rohitha,Kulkarni
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experimental part
p. 3894 - 3902
(2009/04/04)
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- Iodination of activated aromatic compounds using sodium peroxodisulfate and iodine: An efficient way to iodinate alkylated calix[4]arenes
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A simple method for the iodination of activated arenes, using molecular iodine and sodium peroxodisulfate as the oxidant, is presented. The reaction is conducted in the presence of catalytic amounts of tetramethylammonium iodide as a phase-transfer catalyst in acetonitrile. For non-polar substances, which are not soluble in pure acetonitrile such as calix[4]arenes bearing long alkyl chains, a modified reaction is introduced. In this case the phase-transfer catalyst is changed to methyltriphenylphosphonium peroxodisulfate. Chloroform as a cosolvent mediates solubility. Furthermore, we show that the slightly basic conditions obtained upon the addition of sodium bicarbonate have a beneficial effect on the yield. Georg Thieme Verlag Stuttgart.
- Barton, Olaf G.,Mattay, Jochen
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p. 110 - 114
(2008/09/20)
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- Practical electrochemical iodination of aromatic compounds
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A practical method for electrochemical iodination of aromatic compounds was developed. The method involves the generation of I+ by electrochemical oxidation of I2 in CH3CN using H 2SO4 as supporting electrolyte followed by the reaction with aromatic compounds. The para/ortho selectivity for the reaction of mono-substituted benzenes was significantly improved using dimethoxyethane as cosolvent in the second step. The reaction with highly reactive aromatic compounds led to the formation of significant amounts of diiodo compounds in a macrobatch reactor. This problem was solved by fast 1:1 mixing of I+ with an aromatic compound using a microflow system consisting of a T-shaped micromixer and a microtube reactor.
- Kataoka, Kazuhide,Hagiwara, Yuji,Midorikawa, Koji,Suga, Seiji,Yoshida, Jun-Ichi
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p. 1130 - 1136
(2013/01/03)
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- A green reagent for the iodination of phenols
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A new reagent (I2/NaNO2) for the iodination of the aromatic ring of phenols has been discovered. The reaction proceeds at room temperature in 1.5-6 hours. In the presence of this reagent, iodinated compounds are regioselectively formed in significant yields from the corresponding substrates. Georg Thieme Verlag Stuttgart.
- Kiran,Konakahara, Takeo,Sakai, Norio
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experimental part
p. 2327 - 2332
(2009/04/04)
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- Facile preparation of 2-iodophenyl trifluoromethanesulfonates: Superior aryne precursors
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A comparative study of 3-methoxyaryne precursors revealed 2-iodo-3-methoxyphenyl triflate as the most effective in nonpolar solvent. Use of Hoppe's N-isopropyl carbamate allows for the systematic preparation of a variety of 2-iodophenyl triflates via a directed ortho-lithiation-iodination- decarbamation sequence. These steps are possible without isolation of the intermediate iodophenyl carbamates. Georg Thieme Verlag Stuttgart.
- Ganta, Ashok,Snowden, Timothy S.
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p. 2227 - 2231
(2008/02/10)
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- A mild and simple regioselective iodination of activated aromatics with iodine and catalytic ceric ammonium nitrate
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Molecular iodine in the presence of a catalytic amount of CAN has been utilized efficiently for regioselective iodination of activated aromatic compounds under mild reaction conditions.
- Das, Biswanath,Krishnaiah, Maddeboina,Venkateswarlu, Katta,Reddy, V. Saidi
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- Eco-friendly oxyiodination of aromatic compounds using ammonium iodide and hydrogen peroxide
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A new eco-friendly procedure for the oxyiodination of aromatic compounds with NH4I as an iodine source and H2O2 as an oxidant without any catalyst is presented.
- Narender,Reddy, K. Suresh Kumar,Mohan, K.V.V. Krishna,Kulkarni
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p. 6124 - 6128
(2008/03/12)
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- Synthesis of piperidine derivatives by reduction of pyridinium salts
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Piperidine derivatives 1a-e and 2a-f have been prepared by the reduction of 3-and 4-substituted pyridinium salts with NaBH4 in moderate to excellent yields. The reactions regioselectively give 1,2,5,6-tetrahydropyridines, and the yields depend greatly upon the nature of substituents on the phenyl ring and on the nitrogen atom, the nature and the position of the substituents on the pyridyl ring, and the chain length between the aryloxy and the pyridyl groups. Copyright Taylor & Francis Group, LLC.
- Tang, Zilong,Mayrargue, Joelle,Alami, Mouad
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p. 3367 - 3379
(2008/02/13)
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- Efficient synthetic approach to heterocycles possessing the 3,3-disubstituted-2,3-dihydrobenzofuran skeleton via diverse palladium-catalyzed tandem reactions
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Various palladium-catalyzed cascade reactions of O-alkylated 2-iodophenol were explored in order to synthesize novel dihydrobenzofurans. An efficient tandem cyclization/anion capture reaction was developed to yield 3,3-disubstituted-2,3-dihydrobenzofurans. A small library of these compounds was prepared with a parallel organic synthesizer. A multi-component version of this reaction involving 2-iodophenol, an alkylating agent and a nucleophile, provided the same products. The methoxycarbonyl-substituted heterocyclic ring was hydrolyzed to a free acid, which could be used for further transformations.
- Szlosek-Pinaud, Magali,Diaz, Philippe,Martinez, Jean,Lamaty, Frédéric
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p. 3340 - 3349
(2007/10/03)
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- Novel, water-based procedure for the mono iodination of aromatic amines and phenols
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A mixture of potassium chlorate and potassium iodide was found to be a good iodinating agent for various aromatic amines and phenols with excellent yields in the presence of mineral acid in aqueous medium. Copyright Taylor & Francis Group, LLC.
- Sathiyapriya,Joel Karunakaran
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p. 1915 - 1917
(2007/10/03)
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