- Para -Selective C-H bond functionalization of iodobenzenes
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Selective C-H bond activation and functionalization is an invaluable and eco-friendly tool for new chemical bond construction. Recently, great progress has been made in the highly selective ortho- and meta-C-H bond functionalization of arene derivatives. In contrast, the remote para-C-H bond functionalization still remains a challenge. Herein, an oxidation-induced strategy for para-selective C-H bond functionalization of iodobenzenes towards the synthesis of various useful asymmetric diaryl ethers was demonstrated. This strategy not only provides a novel method for para-C-H bond functionalization, but also proposes a general idea for the development of new, highly selective para-C-H functionalization reactions.
- Zhao, Ying,Yan, Haiming,Lu, Hanwei,Huang, Zhiliang,Lei, Aiwen
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- Chiral-at-Ruthenium Catalyst with Sterically Demanding Furo[3,2-b]pyridine Ligands
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A sterically demanding derivative of a previously introduced chiral-at-metal ruthenium(II) catalyst scaffold is introduced. It is composed of two bidentate furo[3,2-b]pyridyl functionalized N-heterocyclic carbene ligands. Their cis-coordination generates helical chirality and a stereogenic ruthenium center. Two additional labile acetonitriles compose the catalytic site which is highly shielded by two 2-(tert-butyl)furo[3,2-b]pyridine moieties. The synthesis of the non-racemic ruthenium catalyst and its catalytic properties for the enantioselective alkynylation of 2,2,2-trifluoroacetophenone and pentafluorobenzaldehyde are reported and compared with sterically less demanding derivatives.
- Cui, Tianjiao,Qin, Jie,Harms, Klaus,Meggers, Eric
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- C-N Coupling via Antiaromatic Endocyclic Nitrenium Ions
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Herein, we report a C-N coupling reaction via antiaromatic endocyclic nitrenium ions. The nitrenium ion intermediate was generated by a combination of iodine(III) reagent PhI(OCOCF3)2 and the N-H center of benzimidazole units at ambient laboratory conditions. Metal-free synthesis of benzimidazole-fused phenanthridine derivatives was achieved in good to excellent yields.
- Bera, Shyamal Kanti,Alam, Md Toufique,Mal, Prasenjit
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- Modifying the Product Distribution of a Reaction within the Controlled Microenvironment of a Colloidosome
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A water-soluble colloidosome composed of PGMA-PS latex was used as a microcapsule to host a catalyzed oxidation reaction within its dodecane core. When compared to a control reaction a significant colloidosome effect was observed. Specifically, a 233% increase in the relative yield of all products was observed for the colloidosome reaction. Furthermore, when the product distributions were calculated it was evident that a switch in selectivity had taken place. These studies showed there is a significant reduction in the relative yield of the epoxide product compared to the remaining oxidation products. Additional control experiments confirmed that rate enhancements were not simply a result of concentration and that reactions were not occurring in the outer latex phase. As a consequence of these control experiments, we suggest that the colloidosome enhancement and shift in product distribution, comes about from differences in electronic environment at or close to the interface between the internal oil phase and the outer colloidal particles. This environment is able to stabilize any specific intermediates and or transition states leading to enhanced reactions for these products and higher relative yields.
- Mann,Ellis,Twyman
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- N?N Bond Formation Using an Iodonitrene as an Umpolung of Ammonia: Straightforward and Chemoselective Synthesis of Hydrazinium Salts
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The formation of hydrazinium salts by N?N bond formation has typically involved the use of hazardous and difficult to handle reagents. Here, mild and operationally simple conditions for the synthesis of hydrazinium salts are reported. Electrophilic nitrogen transfer to the nitrogen atom of tertiary amines is achieved using iodosylbenzene as oxidant and ammonium carbamate as the N-source. The resulting process is highly chemoselective and tolerant to other functional groups. A wide scope is reported, including examples with bioactive molecules. Insights on the structure of hydrazinium salts were provided by X-ray analysis. (Figure presented.).
- Tota, Arianna,Colella, Marco,Carlucci, Claudia,Aramini, Andrea,Clarkson, Guy,Degennaro, Leonardo,Bull, James A.,Luisi, Renzo
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supporting information
p. 194 - 199
(2020/10/28)
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- Synthesis of Diverse Aryliodine(III) Reagents by Anodic Oxidation?
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An anodic oxidation enabled synthesis of hypervalent iodine(III) reagents from aryl iodides is demonstrated. Under mild electrochemical conditions, a range of aryliodine(III) reagents including iodosylarenes, (difunctionaliodo)arenes, benziodoxoles and diaryliodonium salts can be efficiently synthesized and derivatized in good to excellent yields with high selectivity. As only electrons serve as the oxidation reagents, this method offers a more straightforward and sustainable manner avoiding the use of expensive or hazardous chemical oxidants.
- Zu, Bing,Ke, Jie,Guo, Yonghong,He, Chuan
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supporting information
p. 627 - 632
(2021/02/12)
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- CO2-activated NaClO-5H2O enabled smooth oxygen transfer to iodoarene: A highly practical synthesis of iodosylarene
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A safe, rapid, and environmentally friendly synthesis of iodosylarene (ArIO) has been developed using NaClO under a carbon dioxide (CO2) atmosphere. Exposure of iodoarene to NaClO-5H2O in acetonitrile under CO2 (1 atm) resulted in the clean formation of ArIO within 10 minutes in high yield. The absence of a base in this method enables the direct use of in-situ-generated iodosylarene not only for a variety of oxidative transformations (synthesis of sulfilimine, pentavalent bismuth, benzyne adduct, etc.), but also for the synthesis of iodonium ylide and imino-λ3-iodane in one pot.
- Miyamoto, Kazunori,Watanabe, Yuichiro,Takagi, Taisei,Okada, Tomohide,Toyama, Takashi,Imamura, Shinji,Uchiyama, Masanobu
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- Intercepting a transient non-hemic pyridine: N -oxide Fe(iii) species involved in OAT reactions
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In the context of bioinspired OAT catalysis, we developed a tetradentate dipyrrinpyridine ligand, a hybrid of hemic and non-hemic models. The catalytic activity of the iron(iii) derivative was investigated in the presence of iodosylbenzene. Unexpectedly, MS, EPR, M?ssbauer, UV-visible and FTIR spectroscopic signatures supported by DFT calculations provide convincing evidence for the involvement of a relevant FeIII-O-NPy active intermediate. This journal is
- Vo, Nhat Tam,Herrero, Christian,Guillot, Régis,Inceoglu, Tanya,Leibl, Winfried,Clémancey, Martin,Dubourdeaux, Patrick,Blondin, Geneviève,Aukauloo, Ally,Sircoglou, Marie
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supporting information
p. 12836 - 12839
(2021/12/10)
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- PhI(OTf)2 Does Not Exist (Yet)**
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PhI(OTf)2 has been used for the past 30 years as a strong I(III) oxidant for organic and inorganic transformations. It has been reported to be generated in situ from the reactions of either PhI(OAc)2 or PhI=O with two equivalents of trimethylsilyl trifluoromethanesulfonate (TMS-OTf). In this report it is shown that neither of these reactions generate a solution with spectroscopic data consistent with PhI(OTf)2, with supporting theoretical calculations, and thus this compound should not be invoked as the species acting as the oxidant for transformations that have been associated with its use.
- Tania,Houston, Sevan D.,Sharp-Bucknall, Lachlan,Poynder, Tiffany B.,Albayer, Mohammad,Dutton, Jason L.
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supporting information
p. 15863 - 15866
(2020/11/02)
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- Site-Selective Copper-Catalyzed Azidation of Benzylic C-H Bonds
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Site selectivity represents a key challenge for non-directed C-H functionalization, even when the C-H bond is intrinsically reactive. Here, we report a copper-catalyzed method for benzylic C-H azidation of diverse molecules. Experimental and density functional theory studies suggest the benzyl radical reacts with a CuII-azide species via a radical-polar crossover pathway. Comparison of this method with other C-H azidation methods highlights its unique site selectivity, and conversions of the benzyl azide products into amine, triazole, tetrazole, and pyrrole functional groups highlight the broad utility of this method for target molecule synthesis and medicinal chemistry.
- Suh, Sung-Eun,Chen, Si-Jie,Mandal, Mukunda,Guzei, Ilia A.,Cramer, Christopher J.,Stahl, Shannon S.
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supporting information
p. 11388 - 11393
(2020/07/21)
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- SYNTHESIS OF HYPERVALENT IODINE REAGENTS WITH DIOXYGEN
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Methods of synthesis of hypervalent iodine reagents and methods for oxidation of organic compounds are disclosed.
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Paragraph 0065-0067
(2019/01/15)
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- Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A
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The construction of the biologically interesting chromone skeleton was realized by PhIO-mediated dehydrogenation of chromanones under mild conditions. Interestingly, this method also found application in the synthesis of the naturally occurring frutinone A.
- Li, Qiao,Zhuang, Chen,Wang, Donghua,Zhang, Wei,Jia, Rongxuan,Sun, Fengxia,Zhang, Yilin,Du, Yunfei
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supporting information
p. 2958 - 2965
(2020/01/08)
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- Synthesis of Sulfonimidamides from Sulfenamides via an Alkoxy-amino-λ6-sulfanenitrile Intermediate
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Sulfonimidamides are intriguing new motifs for medicinal and agrochemistry, and provide attractive bioisosteres for sulfonamides. However, there remain few operationally simple methods for their preparation. Here, the synthesis of NH-sulfonimidamides is achieved directly from sulfenamides, themselves readily formed in one step from amines and disulfides. A highly chemoselective and one-pot NH and O transfer is developed, mediated by PhIO in iPrOH, using ammonium carbamate as the NH source, and in the presence of 1 equivalent of acetic acid. A wide range of functional groups are tolerated under the developed reaction conditions, which also enables the functionalization of the antidepressants desipramine and fluoxetine and the preparation of an aza analogue of the drug probenecid. The reaction is shown to proceed via different and concurrent mechanistic pathways, including the formation of novel S≡N sulfanenitrile species as intermediates. Several alkoxy-amino-λ6-sulfanenitriles are prepared with different alcohols, and shown to be alkylating agents to a range of nucleophiles.
- Briggs, Edward L.,Tota, Arianna,Colella, Marco,Degennaro, Leonardo,Luisi, Renzo,Bull, James A.
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supporting information
p. 14303 - 14310
(2019/09/06)
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- Enantioselective Synthesis of 3-Heterosubstituted-2-amino-1-ols by Sequential Metal-Free Diene Aziridination/Kinetic Resolution
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A general protocol for the enantioselective synthesis of 3-heterosubstituted-2-amino-1-ols was developed based on metal- free intramolecular regio- and stereoselective diene aziridination and regioselective opening. Kinetic resolution of the resulting (1′-NR1R2 and 1′-SR)-4-oxazolidinones was performed using ABCs organocatalysts, expanding the application of this methodology.
- Giménez-Nueno, Irene,Guasch, Joan,Funes-Ardoiz, Ignacio,Maseras, Feliu,Matheu, M. Isabel,Castillón, Sergio,Díaz, Yolanda
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supporting information
p. 12628 - 12635
(2019/09/16)
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- Transition-Metal-Free Synthesis of Fused Quinazolinones by Oxidative Cyclization of N-Pyridylindoles
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An unprecedented synthesis of fused quinazolinones from N-pyridylindoles under oxidative conditions using a combination of (diacetoxyiodo)benzene and K2S2O8 is reported. The reaction is metal-free, has a broad substrate scope, is operationally simple with short reaction time, and provides 11H-pyrido[2,1-b]quinazolin-11-one derivatives in moderate to high yields. It is believed to proceed via an in situ generated 2-hydroxy-1-(pyridin-2-yl)indolin-3-one as the key reaction intermediate, which undergoes a C-C bond cleavage to produce an electrophilic C-3 site in N-pyridyl indole. Subsequent nucleophilic attack by pyridyl nitrogen results in its cyclization.
- Garia, Alankrita,Jain, Nidhi
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p. 9661 - 9670
(2019/08/26)
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- A putative heme manganese(v)-oxo species in the C-H activation and epoxidation reactions in an aqueous buffer
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A water-soluble manganese(v)-oxo species 1 was generated in the reaction of [Mn(iii)(TPPS)Cl] 2 (TPPS = 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine) and iodosylbenzene (PhIO) in a 2:1 aqueous buffer (pH = 10.4):acetonitrile (CH3CN) mixture. The formula of the EPR silent species 1 is proposed as [Mn(v)(O)(TPPS)Cl] based on the Soret band (422 nm) and Q bands (520, 660 nm) in its UV-vis spectrum and its reaction with thioanisole, regenerating 2 and methyl phenyl sulfoxide. The reactivity of 1 was investigated in the C-H activation of alkyl hydrocarbons and epoxidation of cyclohexene. Based on the observation of the linear correlation of the logarithm of the second rate constant (logk2′) and the bond dissociation energy (BDE, kcal mol-1) of alkyl hydrocarbons along with a large kinetic isotope effect (KIE = 8.5) for xanthene vs. xanthene-d2, we propose H-atom abstraction as the rate determining step in the C-H activation reactions. On the other hand, in contrast to the C-H activation reaction, cyclohexene, which has a weak C-H bond (BDE = 82.5 kcal mol-1), undergoes an epoxidation reaction.
- Harmalkar, Dinesh S.,Santosh,Shetgaonkar, Siddhi B.,Sankaralingam, Muniyandi,Dhuri, Sunder N.
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supporting information
p. 12900 - 12906
(2019/08/28)
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- A trivalent hypervalent iodine compound using hypochlorite (by machine translation)
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[A] used in the prior art organic salt, toxic chlorine gas, organic peroxides can be used without the novel trivalent hypervalent iodine compound production. Furthermore, the acyloxy groups other than the trivalent hypervalent iodine compounds having a ligand manufacturing method. (1) Formula [solution](In the formula, R1 Substituted/unsubstituted aromatic group, aliphatic group or the like. N is an integer of 1 or more. ) Represented by the iodine compound, carboxylic acid, carboxylic acid anhydride, a sulfonic acid or sulfonic acid anhydride with at least one organic acid selected from the group consisting of, a hypochlorite mixing, trivalent hypervalent iodine compound. [Drawing] no (by machine translation)
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Paragraph 0065
(2020/02/14)
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- Hypervalent Iodine(III)-Mediated Regioselective Cyanation of Quinoline N-Oxides with Trimethylsilyl Cyanide
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A regioselective cyanation of quinoline N-oxides with trimethylsilyl cyanide was developed by using (Diacetoxyiodo) benzene (PIDA) as mediated hypervalent iodine(III) reagent under metal-free and base-free reaction conditions to obtain 2-cyanoquinolines. The efficient PIDA reagent could play the role of an activator of the substrates and an accelerator of N?O bond cleavage. The reaction system featured a wide range of substrate suitability and high yields. The procedure was enlarged gram-scale to synthesize the tuberculosis (TB) inhibitor. Finally, according to some experimental results, a plausible mechanism for the cyanation reaction is proposed. (Figure presented.).
- Xu, Feng,Li, Yuqin,Huang, Xin,Fang, Xinjie,Li, Zhuofei,Jiang, Hongshuo,Qiao, Jingyi,Chu, Wenyi,Sun, Zhizhong
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supporting information
p. 520 - 525
(2018/12/13)
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- Oxidase catalysis via aerobically generated hypervalent iodine intermediates
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The development of sustainable oxidation chemistry demands strategies to harness O'2 as a terminal oxidant. Oxidase catalysis, in which O'2 serves as a chemical oxidant without necessitating incorporation of oxygen into reaction products, would allow diverse substrate functionalization chemistry to be coupled to O'2 reduction. Direct O'2 utilization suffers from intrinsic challenges imposed by the triplet ground state of O'2 and the disparate electron inventories of four-electron O'2 reduction and two-electron substrate oxidation. Here, we generate hypervalent iodine reagents - a broadly useful class of selective two-electron oxidants - from O'2. This is achieved by intercepting reactive intermediates of aldehyde autoxidation to aerobically generate hypervalent iodine reagents for a broad array of substrate oxidation reactions. The use of aryl iodides as mediators of aerobic oxidation underpins an oxidase catalysis platform that couples substrate oxidation directly to O'2 reduction. We anticipate that aerobically generated hypervalent iodine reagents will expand the scope of aerobic oxidation chemistry in chemical synthesis.
- Maity, Asim,Hyun, Sung-Min,Powers, David C.
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p. 200 - 204
(2018/02/06)
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- Sulfonimidates: Useful Synthetic Intermediates for Sulfoximine Synthesis via C-S Bond Formation
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Medicinally relevant sulfoximines are accessed from C-S coupling of sulfonimidates and commercially available organomagnesium reagents. Sulfonimidates are conveniently synthesized by oxidative alkoxylation of readily available sulfinamides. This constitutes a general C-S coupling approach for the synthesis of sulfoximines.
- Matos, Priscilla Mendon?a,Lewis, William,Moore, Jonathan C.,Stockman, Robert A.
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supporting information
p. 3674 - 3677
(2018/06/26)
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- PhIO/Et3N ? 3HF-Mediated Formation of Fluorinated 2H-Azirines via Domino Fluorination/Azirination Reaction of Enamines
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A variety of enamine carboxylic esters and enaminones were converted to the biologically interesting fluorinated 2H-azirines through reactions with PhIF2 generated in situ by PhIO and Et3N ? 3HF in 1,2-dichroloethane, which features the hypervalent iodine reagents-mediated introduction of fluorine atom and formation of the 2H-azirine skeleton under metal-free conditions. The domino reaction is postulated to proceed via a PhIF2-mediated oxidative fluorination and a subsequent azirination of the fluorinated enamine intermediates. (Figure presented.).
- Zhang, Yong,Zhao, Xiaoyuan,Zhuang, Chen,Wang, Senlin,Zhang-Negrerie, Daisy,Du, Yunfei
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supporting information
p. 2107 - 2112
(2018/04/19)
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- Diastereoselective and Enantiospecific Synthesis of 1,3-Diamines via 2-Azaallyl Anion Benzylic Ring-Opening of Aziridines
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The 1,3-diamine motif appears in numerous complex molecules, yet there are few methods for the stereoselective construction of this moiety. Herein, we demonstrate a stereocontrolled synthesis of 1,3-diamines, which bear up to three contiguous stereogenic centers, through benzylic ring-opening of aziridines with 2-azaallyl anion nucleophiles. Reactions proceed efficiently (yield up to 95%), diastereoselectively (dr up to >20:1), site selectively, and enantiospecifically to deliver products with differentiated amino groups.
- Li, Kangnan,Weber, Alexandria E.,Tseng, Luke,Malcolmson, Steven J.
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supporting information
p. 4239 - 4242
(2017/08/23)
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- One-Pot Acid-Catalyzed Ring-Opening/Cyclization/Oxidation of Aziridines with N-Tosylhydrazones: Access to 1,2,4-Triazines
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A new, three-step, telescoped reaction sequence for the regioselective conversion of N-tosyl hydrazones and aziridines to 3,6-disubstituted and 3,5,6-trisubstituted 1,2,4-triazines is described. The process involves an efficient nucleophilic ring opening of the aziridine, giving access to a wide range of aminohydrazones, isolated with excellent yields. A “one-pot” procedure, combining the ring opening with a cyclization and an oxidation step, allows the preparation of diversified triazines in good yields.
- Crespin, Lorène,Biancalana, Lorenzo,Morack, Tobias,Blakemore, David C.,Ley, Steven V.
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supporting information
p. 1084 - 1087
(2017/03/15)
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- NH2-directed C-H alkenylation of 2-vinylanilines with vinylbenziodoxolones
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The first directing-group-mediated C-H alkenylation with alkenyl-λ3-iodanes as electrophilic alkene-transfer reagents has been developed. The application of free aromatic amines as challenging but synthetically valuable directing groups in combination with an IrIII catalyst enabled the synthesis of highly desirable 1, 3- dienes in excellent yields of up to 98% with high to perfect (Z, E) stereoselectivity. A broad substrate scope and further synthetic modifications are demonstrated.
- Boelke, Andreas,Caspers, Lucien D.,Nachtsheim, Boris J.
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supporting information
p. 5344 - 5347
(2017/11/07)
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- A convenient synthesis of a porphyrin cross-linked polymer, its application as a size selective heterogeneous catalyst and a comparison with a porphyrin-cored hyperbranched polymer
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This paper describes how the polymeric structure and environment surrounding supported catalysts can be used to affect the product outcome from a reaction. As well as reporting a size/shape selectivity, we also describe a significant effect on product distribution. Specifically, how the polymeric environment can favour or disfavour particular products. As such, these results illustrate how it may be possible to target more or less of a specific compound (from a possible mix) by careful choice of the polymer architecture surrounding a catalyst.
- Twyman, Lance J.,Zheng, Xinwei
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p. 617 - 623
(2016/06/09)
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- Design and Synthesis of Irreversible Analogues of Bardoxolone Methyl for the Identification of Pharmacologically Relevant Targets and Interaction Sites
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Semisynthetic triterpenoids such as bardoxolone methyl (methyl-2-cyano 3,12-dioxooleano-1,9-dien-28-oate; CDDO-Me) (4) are potent inducers of antioxidant and anti-inflammatory signaling pathways, including those regulated by the transcription factor Nrf2. However, the reversible nature of the interaction between triterpenoids and thiols has hindered attempts to identify pharmacologically relevant targets and characterize the sites of interaction. Here, we report a shortened synthesis and SAR profiling of 4, enabling the design of analogues that react irreversibly with model thiols, as well as the model protein glutathione S-transferase P1, in vitro. We show that one of these analogues, CDDO-epoxide (13), is comparable to 4 in terms of cytotoxicity and potency toward Nrf2 in rat hepatoma cells and stably modifies specific cysteine residues (namely, Cys-257, -273, -288, -434, -489, and -613) within Keap1, the major repressor of Nrf2, both in vitro and in living cells. Supported by molecular modeling, these data demonstrate the value of 13 for identifying site(s) of interaction with pharmacologically relevant targets and informing the continuing development of triterpenoids as novel drug candidates.
- Wong, Michael H. L.,Bryan, Holly K.,Copple, Ian M.,Jenkins, Rosalind E.,Chiu, Pak Him,Bibby, Jaclyn,Berry, Neil G.,Kitteringham, Neil R.,Goldring, Christopher E.,O'Neill, Paul M.,Park, B. Kevin
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p. 2396 - 2409
(2016/04/10)
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- Encapsulation of chiral Fe(salen) in mesoporous silica structures for use as catalysts to produce optically active sulfoxides
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Solid catalysts which are heterogeneous at the macroscopic scale but homogeneous at the microscopic level were prepared by the encapsulation of Fe(salen) by a "ship in a bottle" approach. This approach permits the synthesis of a "free" Fe(salen) complex inside the nanocages of SBA-16 and m-MCF, having conformational freedom and behaving as a complex in solution. These materials were used as catalysts for asymmetric oxidation of sulfides. The entrance sizes of the mesoporous materials SBA-16 and m-MCF were tuned by changing the synthesis parameters and by silylation of the silica surface with n-propyl groups, which resulted in materials with different Fe(salen) loadings. Chiral Fe(salen) trapped in m-MCF materials showed higher activity than the complex immobilized on SBA-16. The activity and enantioselectivity of the catalysts based on m-MCF were on a par with the homogeneous counterpart under specific conditions. The heterogenized catalysts presented a limited recyclability; however, they were clearly advantageous compared to the homogenous counterpart, where reutilization was not possible.
- Oliveira, Rafael L.,Nijholt, Tom,Shakeri, Mozaffar,De Jongh, Petra E.,Gebbink, Robertus J. M. Klein,De Jong, Krijn P.
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p. 5124 - 5133
(2016/07/11)
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- Fluorination of aromatic compounds with xenon difluoride in the presence of boron trifluoride etherate
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Fluorination of benzene with the XeF2 - BF3?Et2O system in acetonitrile at low temperatures affords fluorobenzene in 18% yield, the conversion of benzene being 92%. The rest products are di-, tri-, tetra-, and polyphenyls with different fluorination pattern. Toluene and chloro- and bromobenzenes are fluorinated predominantly at the ortho and para positions. Fluorination of 4-nitroanisole affords 2-fluoro-4-nitroanisole in 73% yield.
- Fedorov,Zubarev,Mortikov, V. Yu.,Rodinovskaya,Shestopalov
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p. 1049 - 1052
(2016/02/09)
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- Studies on the formal [3 + 2] cycloaddition of aziridines with alkenes for the synthesis of 1-azaspiroalkanes
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The Lewis acid-mediated [3 + 2] cycloaddition of N-sulfonyl- and N-sulfamoylaziridines with alkenes provides a rapid and efficient access to 1-azaspiro[4.n]alkanes. Experimental studies have been combined with DFT calculations to explore the mechanism of the reaction. They demonstrate that the nature of the electron-withdrawing nitrogen protecting group has a very limited influence on the course of the reaction and, particularly, on the initial formation of the 1,3-zwitterionic species through C-N bond cleavage, which has been found to be the rate-determining step. Compared to N-sulfonylaziridines, N-sulfamoylaziridines have proved to be more synthetically useful synthons that afford crystalline polycyclic structures in good yields. A short sequence of catalytic C(sp3)-H amination-cyclization-[3 + 2] cycloaddition has then been successfully designed to afford the homologue 1-azaspiro[5.n]alkanes, thereby illustrating the higher versatility of sulfamates in these cycloadditions.
- Martinand-Lurin, Elodie,Gruber, Raymond,Retailleau, Pascal,Fleurat-Lessard, Paul,Dauban, Philippe
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p. 1414 - 1426
(2015/02/19)
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- Umpolung Strategy for Synthesis of β-Ketonitriles through Hypervalent Iodine-Promoted Cyanation of Silyl Enol Ethers
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An efficient method to synthesize β-ketonitriles from silyl enol ethers by an umploung hypervalent iodine(III)-CN species generated in situ from PhIO/BF3·Et2O/TMSCN has been developed for the first time. This method can be applied to structurally diverse aromatic and aliphatic substrates and further extended to preparation of bioactive compounds like 5-aminopyrazole and 5-aminoisoxazole.
- Shen, Hang,Li, Jiaqiang,Liu, Qing,Pan, Jing,Huang, Ruofeng,Xiong, Yan
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p. 7212 - 7218
(2015/07/28)
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- METHODS AND COMPOSITIONS FOR DIRECT RADIOACTIVE LABELING OF BIO-ACTIVE MOLECULES AND BUILDING BLOCKS
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Methods of direct radioactive labeling a carbon containing compound having an sp3 C-H bond are provided. Methods of carrier-free 18F fluorination of a carbon containing compound mediated by manganese salen complexes or manganese porphyrin complexes comprising weakly coordinated anions as axial ligands are provided. Methods of "dry-down" free radioactive labeling of a carbon containing compound having an sp3 C-H bond are provided. The radioactively labeled products of the methods are provided.
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Paragraph 00106
(2015/11/02)
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- Oxidations of alkenes with hypervalent iodine reagents: An alternative ozonolysis of phenyl substituted alkenes and allylic oxidation of unsubstituted cyclic alkenes
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Unsaturated CC double bonds with a phenyl substituent can be cleaved with iodylbenzene and iodosylbenzene to give carbonyl compounds. It is believed that the reactions occur via a radical pathway. The allylic oxidation of cyclic alkenes lacking a phenyl substituent was achieved in acetonitrile/water mixture (3:1) also using iodylbenzene and iodosylbenzene.
- Atmaca, Ufuk,Usanmaz, Hande K.,?elik, Murat
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supporting information
p. 2230 - 2232
(2014/04/17)
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- Late stage benzylic C-H fluorination with [18F]fluoride for PET imaging
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We describe the first late-stage 18F labeling chemistry for aliphatic C-H bonds with no-carrier-added [18F]fluoride. The method uses Mn(salen)OTs as an F-transfer catalyst and enables the facile labeling of a variety of bioactive molecules and building blocks with radiochemical yields (RCY) ranging from 20% to 72% within 10 min without the need for preactivation of the labeling precursor. Notably, the catalyst itself can directly elute [18F]fluoride from an ion exchange cartridge with over 90% efficiency. Using this feature, the conventional and laborious dry-down step prior to reaction is circumvented, greatly simplifying the mechanics of this protocol and shortening the time for automated synthesis. Eight drug molecules, including COX, ACE, MAO, and PDE inhibitors, have been successfully [ 18F]-labeled in this way.
- Huang, Xiongyi,Liu, Wei,Ren, Hong,Neelamegam, Ramesh,Hooker, Jacob M.,Groves, John T.
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p. 6842 - 6845
(2014/06/09)
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- Improving alkynyl(aryl)iodonium salts: 2-anisyl as a superior aryl group
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The majority of alkynyl(aryl)iodonium salts reported in the literature are derived from iodobenzene. This article describes the effects of varying this iodoarene building block on the synthesis, reactivity and stability of these salts. Two procedures to synthesize a variety of known and novel alkynyl(aryl)iodonium tosylates directly from the iodoarene are reported. In the reactions of these salts, those derived from 2-iodoanisole gave superior results than the others tested in every reaction. Isothermal microcalorimetry indicated that these novel salts were significantly more stable and less prone to decomposition than all of the other derivatives. This journal is the Partner Organisations 2014.
- Hamnett, David J.,Moran, Wesley J.
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p. 4156 - 4162
(2014/06/10)
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- Binuclear iron(III) octakis(perfluorophenyl)tetraazaporphyrin μ-oxodimer: A highly efficient catalyst for biomimetic oxygenation reactions
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Binuclear iron(III) octakis(perfluorophenyl)tetraazaporphyrin μ-oxodimer complex was prepared by the reaction of bis(perfluorophenyl)maleonitrile and Fe(CO)5and tested in catalytic oxygenation reactions of several hydrocarbons in comparison with the analogous non-fluorinated phthalocyanine complexes. Results of the study demonstrate that this complex is a highly efficient catalyst for the oxygenation of anthracene, 2-tert-butylanthracene, naphthalene, 2-methylnaphthalene, phenanthrene, adamantane, and toluene using iodosylbenzene, oligomeric iodosylbenzene sulfate, or Oxone as stoichiometric oxidants.
- Yusubov, Mekhman S.,Celik, Cumali,Geraskina, Margarita R.,Yoshimura, Akira,Zhdankin, Viktor V.,Nemykin, Victor N.
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supporting information
p. 5687 - 5690
(2014/12/11)
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- Synthesis and reactivity of aryl(alkynyl)iodonium salts
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The first practical, yet simple, preparation of aryl(alkynyl)iodonium trifluoroacetate salts is described. The generic nature of this synthetic method has allowed the production of a range of aryl(alkynyl)iodonium trifluoroacetate salts with independent variation of both the alkynyl and aryliodo groups in yields of 30-85 %. Application of these new reagents to the synthesis of a series of 2-arylfuro[3,2-c]pyridines (40-64 %) highlights the potential of this class of materials as precursors to bioactive heterocyclic structures. These experiments have also demonstrated that, in this case, the effect of the aryliodo group on the reaction is negligible.
- Dixon, Luke I.,Carroll, Michael A.,Gregson, Thomas J.,Ellames, George J.,Harrington, Ross W.,Clegg, William
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supporting information
p. 2334 - 2345
(2013/05/21)
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- Manganese-catalyzed oxidative benzylic C-H fluorination by fluoride ions
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An efficient protocol for the selective fluorination of benzylic C-H bonds is described. The process is catalyzed by manganese salen complexes and uses nucleophilic fluorine sources, such as triethylamine trihydrofluoride and KF. Reaction rates are sufficiently high (30min) to allow adoption for the incorporation of 18F fluoride sources for PET imaging applications. Copyright
- Liu, Wei,Groves, John T.
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supporting information
p. 6024 - 6027
(2013/07/04)
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- Probing dense packed limits of a hyperbranched polymer through ligand binding and size selective catalysis
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In the area of dendritic chemistry (hyperbranched polymers and dendrimers) it is often generalized that dendrimers are the molecule of choice for smart, selective, or technical applications involving encapsulation or controlled/selective environments. This is despite the fact that hyperbranched polymers (HBP)s are generally easier and cheaper to synthesize, making them more amenable to large-scale applications. Dendrimers have been successful in these applications by virtue of a dense packed or dense shell limit. This paper describes the synthesis of a series of narrowly dispersed HBPs possessing binding and catalytic cores with a high and uniform loading. Subsequent binding experiments clearly demonstrated the existence of a dense packed limit with respect to polymer molecular weight and ligand size. A series of catalytic experiments were also performed in an attempt to exploit these molecules and their dense packed limit to the area of shape/size selective catalysis - an area where dendrimers have previously been used with celebrated success. However, although we were able to show the existence of a dense packed limit, we were initially unable to demonstrate any selectivity based on substrate size or shape. Nevertheless, further studies into core branching motif and multiplicity eventually enabled us to obtain a series of HBPs capable of perturbing the shape/size selectivity of a simple oxidation reaction involving two alkenes. Specifically, we were able to demonstrate a 3.5-fold shift in chemoselectivity toward a smaller alkene of lower reactivity. These results compare favorably with those obtained using dendrimers and allow us to conclude that, with careful thought regarding core design, HBPs are indeed capable of being applied to technical/smart applications involving controlled and selective environments.
- Ellis, Adam,Twyman, Lance J.
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p. 7055 - 7074
(2013/09/24)
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- Wittig reagents as metallocarbene precursors: In situ generated monocarbonyl iodonium ylides
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A proof of concept study was undertaken to determine the suitability of monocarbonyl iodonium ylides (MCIYs) as metallocarbene precursors. Exposing Wittig reagents to iodosylbenzene results in a pseudo-Wittig reaction that generates MCIYs in situ. These ylides are intercepted by transition-metal catalysts to generate metallocarbenes, which then undergo either dimerization or cyclopropanation reactions with a variety of alkenes. Additionally, the reaction between diazoester-derived metallocarbenes and Wittig reagents afforded cross-coupling products, illustrating a new type of olefination reaction for phosphonium ylides. Monocarbonyl iodonium ylides (MCIYs) represent a possible alternative to the use diazoketones and -esters as metallocarbene precursors. Upon treatment with iodosylbenzene, a Wittig reagent will undergo ylide transfer to generate a MCIY in situ. In the presence of transition-metal catalysts, MCIYs serve as precursors to metallocarbenes, which undergo dimerization or cyclopropanation of alkenes. tfacac = trifluoroacetylacetonate. Copyright
- Ho, Phyllis E.,Tao, Jason,Murphy, Graham K.
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supporting information
p. 6540 - 6544
(2013/11/06)
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- Oxidative cleavage of α-aryl aldehydes using iodosylbenzene
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We found that α-aryl aldehydes can be cleaved to chain-shortened carbonyl compounds and formaldehyde by various iodosylbenzene complexes. A mechanistic scheme is presented that accounts for the loss of one carbon atom. Formaldehyde is further oxidized to CO and CO2 under the reaction conditions.
- Havare, Nizam,Plattner, Dietmar A.
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supporting information
p. 5078 - 5081,4
(2020/09/15)
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- Study on anti-proliferative effect of benzoxathiole derivatives through inactivation of NF-κB in human cancer cells
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To investigate the anti-proliferative effect of a newly discovered NF-kB inhibitor, 6,6-dimethyl-2-(phenylimino)-6,7-dihydrobenzo[d][1,3]oxathiol-4(5H)- one (1a), a series of its analogs (1b-n) were prepared and evaluated for their NF-κB inhibition and anti-proliferative activity against various human cancer cell lines. Slight variation of hydrophobicity by replacement of dimethyl group of 1a at 6-position with bulky isopropyl group and introduction of para-fluoro substitution on 2-phenyl group showed good NF-κB inhibitory activity and anti-proliferative activity. However, excessive increase in hydrophobicity with 2,4,6-trichloro substituents on phenyl group resulted in the loss of both the activities. From the SAR results, 2-phenylimino-6,7- dihydrobenzo[d][1,3]oxathiol-4(5H)-one was identified as the lead scaffold for investigating new anticancer agent through inactivation of NF-κB.
- Venkateswararao, Eeda,Anh, Hoang Le Tuan,Sharma, Vinay K.,Lee, Ki-Cheul,Sharma, Niti,Kim, Youngsoo,Jung, Sang-Hun
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supporting information; experimental part
p. 4523 - 4527
(2012/08/07)
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- Nickel-catalyzed negishi alkylations of styrenyl aziridines
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A nickel-catalyzed cross-coupling reaction between N-sulfonyl aziridines and organozinc reagents is reported. The catalytic system comprises an inexpensive and air-stable Ni(II) source and dimethyl fumarate as ligand. Regioselective synthesis of β-substituted amines is possible under mild and functional-group-tolerant conditions. The stereoselectivity of the reaction is consistent with a stereoconvergent mechanism wherein the sulfonamide directs C-C bond formation.
- Huang, Chung-Yang,Doyle, Abigail G.
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supporting information; experimental part
p. 9541 - 9544
(2012/07/14)
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- Selective oxidation of terminal aryl and aliphatic alkenes to aldehydes catalyzed by iron(iii) porphyrins with triflate as a counter anion
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[Fe(Por)CF3SO3] (Por = porphyrin dianion) can efficiently catalyze selective oxidation of terminal aryl alkenes and aliphatic alkenes to aldehydes in good to high yields under mild conditions.
- Chen, Guo-Qiang,Xu, Zhen-Jiang,Zhou, Cong-Ying,Che, Chi-Ming
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supporting information; experimental part
p. 10963 - 10965
(2011/11/06)
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- Do trinuclear triplesalen complexes exhibit cooperative effects? Synthesis, characterization, and enantioselective catalytic sulfoxidation by chiral trinuclear FeIII triplesalen complexes
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The chiral triplesalen ligand H6chand provides three chiral salen ligand compartments in a meta-phenylene arrangement by a phloroglucinol backbone. The two diastereomeric versions H6chand RR and H 6chand rac have been used to synthesize the enantiomerically pure chiral complex [(FeCl)3-(chand RR)] (3 RR) and the racemic complex [(FeCl)3(chand rac)] (3 rac). The molecular structure of the free ligand H6chand rac exhibits at the terminal donor sides the O-protonated phenol-imine tautomer and at the central donor sides the N-protonated keto-enamine tautomer. The trinuclear complexes are comprised of five-coordinate square-pyramidal Fe III ions with a chloride at the axial positions. The crystal structure of 3 rac exhibits collinear chiral channels of ~11 A in diameter making up 33.6 % of the volume of the crystals, whereas the crystal structure of 3 RR exhibits voids of 560 A 3. Moessbauer spectroscopy demonstrates the presence of Fe III high-spin ions. UV/Vis spectroscopy is in accordance with a large delocalized system in the central backbone evidenced by strong low-energy shifts of the imine π-π * transitions relative to that of the terminal units. Magnetic measurements reveal weak intramolecular exchange interactions but strong magnetic anisotropies of the Fe III ions. Complexes 3 rac and 3 RR are good catalysts for the sulfoxidation of sulfides providing very good yields and high selectivities with 3 RR being enantioselective. A comparison of 3 RR and [FeCl-(salen')] provides higher yields and selectivities but lower enantiomeric excess values (ee values) for 3 RR relative to [FeCl(salen')]. The low ee values of 3 RR appeared to be connected to a strong ligand folding in 3 RR, opening access to the catalytically active high-valent Fe-O species. The higher selectivity is assigned to a cooperative stabilization of the catalytically active high-valent Fe-O species through the phloroglucinol backbone in the trinuclear complexes.
- Mukherjee, Chandan,Stammler, Anja,Boegge, Hartmut,Glaser, Thorsten
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experimental part
p. 10137 - 10149
(2010/11/20)
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- Synthesis, characterization, and catalytic activity of anionic iron(III) porphyrins intercalated into layered double hydroxides
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The first generation free-base anionic porphyrin [H2(TSPP)]4-, its iron(III) porphyrin [Fe(TSPP)]3-, and the second generation anionic complexes [Fe(TDFSPP)]3- and [Fe(TDCSPP)]3- were intercalated into the layered double hydroxide ZnnAl-LDH (n = 2, 4 or 5) by coprecipitation at constant pH. The materials were characterized by X-ray powder diffraction, UV/visible spectroscopy in glycerin mull, attenuated total reflectance Fourier transform infrared spectroscopy, and electron paramagnetic resonance. Results revealed that the coprecipitation method led to intercalation of the free-base porphyrin and the iron(III) porphyrins between the ZnnAl-LDH layers. The materials were used as catalysts in the oxidation of cyclooctene, cyclohexene, and cyclohexane by iodosylbenzene. The catalytic activity of [Fe(TDCSPP)]-Zn2Al-LDH was higher than that of the homogeneous [Fe(TDCSPP)]3-, but the opposite effect was observed in the case of [Fe(TDFSPP)]-Zn2Al-LDH. Although [Fe(TDFSPP)]3- and [Fe(TDCSPP)]3- are structurally similar, their intercalation into Zn2Al-LDH likely results in different chemical environments, leading to distinct catalytic activities.
- Halma, Matilte,Aparecida Dias de Freitas Castro, Kelly,Taviot-Gueho, Christine,Prevot, Vanessa,Forano, Claude,Wypych, Fernando,Nakagaki, Shirley
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experimental part
p. 233 - 243
(2009/02/05)
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- A method for detecting water in organic solvents
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(Chemical Equation Presented) The potent dehydrating ability of difluoro(aryl)-λ3-iodanes is exploited to develop a convenient 19F-NMR-based aquametry method that is more sensitive than coulometric Karl Fischer titration. The key difluoro(aryl)-λ3- iodane reagents are synthesized readily from commercially available and inexpensive precursors.
- Sun, Haoran,Wang, Bijia,Dimagno, Stephen G.
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supporting information; experimental part
p. 4413 - 4416
(2009/05/27)
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- Rhodium(II)-catalyzed inter- and intramolecular cyclopropanations with diazo compounds and phenyliodonium ylides: Synthesis and chiral analysis
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Different classes of cyclopropanes derived from Meldrum's acid (=2,2-dimethyl-1,3-dioxane-4,6-dione; 4), dimethyl malonate (5), 2-diazo-3-(silyloxy)but-3-enoate 16, 2-diazo-3,3,3-trifluoropropanoate 18, diazo(triethylsilyl)acetate 24a, and diazo(dimethylphenylsilyl)acetate 24b were prepared via dirhodium(II)-catalyzed intermolecular cyclopropanation of a set of olefins 3 (Schemes 1 and 4-6). The reactions proceeded with either diazo-free phenyliodonium ylides or diazo compounds affording the desired cyclopropane derivatives in either racemic or enantiomer-enriched forms. The intramolecular cyclopropanation, of allyl diazo(triethylsilyl)acetates 28, 30, and 33 were carried out in the presence of the chiral dirhodium(II) catalyst [Rh 2{(S)-nttl)4}] (9) in toluene to afford the corresponding cyclopropane derivatives 29, 31 and 34 with up to 37% ee (Scheme 7). An efficient enantioselective chiral separation method based on enantioselective GC and HPLC was developed. The method provides information about the chemical yields of the cyclopropane derivatives, enantioselectivity, substrate specifity, and catalytic activity of the chiral catalysts used in the inter- and intramolecular cyclopropanation reactions and avoids time-consuming workup procedures.
- Ghanem, Ashraf,Lacrampe, Fabienne,Schurig, Volker
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p. 216 - 239
(2007/10/03)
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- Rh(II)-catalyzed enantioselective cyclopropanation of olefins with dimethyl malonate via in situ generated phenyliodonium ylide
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(Chemical Equation Presented) Olefins are cyclopropanated with dimethyl malonate (1a) iodosylbenzene (Phl=O) and a Rh(II) carboxylate catalyst via an in situ generated phenyliodonium ylide (1c). Enantioselectivities of up to 90% for 4-bromostyrene and 98% for pent-1-ene have been observed with (S)-N-4-bromo-1,8-naphthanoyl-tert-leucine (4c) as the chiral ligand. The same catalyst was effective for olefin cyclopropanation with Meldrum's acid, giving cyclopropanes with 96% (with styrene) and 87% ee (with pent-1-ene), respectively.
- Muller, Paul,Ghanem, Ashraf
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p. 4347 - 4350
(2007/10/03)
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- A practical synthetic method of iodoarene difluorides without fluorine gas and mercury salts
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Iodoarene difluorides were synthesized in three steps from the corresponding iodoarenes without the use of dangerous reagents such as fluorine gas of harmful mercury salts.
- Sawaguchi, Masanori,Ayuba, Shinichi,Hara, Shoji
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p. 1802 - 1803
(2007/10/03)
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