- Mechanistic studies of copper-catalyzed alkene aziridination
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The mechanism of the copper-catalyzed aziridination of alkenes using [N-(p-toluenesulfonyl)imino]-phenyliodinane (PhINTs) as the nitrene source has been elucidated by a combination of hybrid density functional theory calculations (B3LYP) and kinetic exper
- Brandt, Peter,Soedergren, Mikael J.,Andersson, Pher G.,Norrby, Per-Ola
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Read Online
- Method for preparing azabicyclic compounds
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The method comprises the following steps: a compound of the formula II and a compound of the formula III react under the action of a Lewis acid [3 + 2], the azabicyclic compound represented by the formula I is obtained, and the reaction formula is as shown below. The method has the advantages of wide substrate adaptability range, mild reaction conditions, less reaction steps, high atom economy, high yield and stereoselectivity and the like.
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Paragraph 0099-0100; 0102
(2021/11/14)
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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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- Cobalt-Catalyzed Hydroalkynylation of Vinylaziridines
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Transition metal-catalyzed hydroalkynylation reactions are efficient transformations allowing the straightforward formation of functionalized alkynes. Therein, we disclose the cobalt-catalyzed hydroalkynylation of vinylaziridines giving rise to both linea
- Biletskyi, Bohdan,Kong, Lingyu,Tenaglia, Alphonse,Clavier, Hervé
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supporting information
p. 2578 - 2585
(2021/03/18)
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- Ni-Catalyzed Carboxylation of Aziridines en Route to β-Amino Acids
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A Ni-catalyzed reductive carboxylation of N-substituted aziridines with CO2 at atmospheric pressure is disclosed. The protocol is characterized by its mild conditions, experimental ease, and exquisite chemo- and regioselectivity pattern, thus unlocking a new catalytic blueprint to access β-amino acids, important building blocks with considerable potential as peptidomimetics.
- Davies, Jacob,Janssen-Müller, Daniel,Zimin, Dmitry P.,Day, Craig S.,Yanagi, Tomoyuki,Elfert, Jonas,Martin, Ruben
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supporting information
p. 4949 - 4954
(2021/04/07)
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- Expedient Synthesis of 2-Iminothiazolidines via Telescoping Reactions Including Iron-Catalyzed Nitrene Transfer and Domino Ring-Opening Cyclization (DROC)
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2-iminothiazolidines are important scaffold for pharmaceutical drugs. Herein, we describe a fast and easy procedure for their synthesis by a telescoping reaction integrating an iron-catalyzed nitrene transfer under mild conditions. The aziridination react
- Coin, Guillaume,de Ferrier de Montal, Oriane,Dubourdeaux, Patrick,Latour, Jean-Marc
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supporting information
p. 443 - 448
(2020/12/11)
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- Imidazoline synthesis: Mechanistic investigations show that Fe catalysts promote a new multicomponent redox reaction
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Multicomponent reactions are attracting strong interest because they contribute to develop more efficient synthetic chemistry. Understanding their mechanism at the molecular level is thus an important issue to optimize their operation. The development of
- Bayle, Pierre-Alain,Coin, Guillaume,Dubourdeaux, Patrick,Latour, Jean-Marc,Lebrun, Colette,Maldivi, Pascale
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supporting information
p. 6512 - 6519
(2021/05/26)
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- HKUST-1 Metal Organic Framework as an Efficient Dual-Function Catalyst: Aziridination and One-Pot Ring-Opening Transformation for Formation of β-Aryl Sulfonamides with C-C, C-N, C-S, and C-O Bonds
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Metal-organic frameworks (MOFs) are extensively used in catalysis due to their robust structure, well-defined periodic reaction centers, and high porosity. We report Cu3(BTC)2·(H2O)3 (HKUST-1) as an efficient heterogeneous catalyst for aziridination of al
- Sharma, Debesh,Rasaily, Sagarmani,Pradhan, Sajan,Baruah, Khanindram,Tamang, Sudarsan,Pariyar, Anand
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supporting information
p. 7794 - 7802
(2021/05/26)
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- Ligand Redox Noninnocence in [CoIII(TAML)]0/- Complexes Affects Nitrene Formation
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The redox noninnocence of the TAML scaffold in cobalt-TAML (tetra-amido macrocyclic ligand) complexes has been under debate since 2006. In this work, we demonstrate with a variety of spectroscopic measurements that the TAML backbone in the anionic complex [CoIII(TAMLred)]- is truly redox noninnocent and that one-electron oxidation affords [CoIII(TAMLsq)]. Multireference (CASSCF) calculations show that the electronic structure of [CoIII(TAMLsq)] is best described as an intermediate spin (S = 1) cobalt(III) center that is antiferromagnetically coupled to a ligand-centered radical, affording an overall doublet (S = 1/2) ground-state. Reaction of the cobalt(III)-TAML complexes with PhINNs as a nitrene precursor leads to TAML-centered oxidation and produces nitrene radical complexes without oxidation of the metal ion. The ligand redox state (TAMLred or TAMLsq) determines whether mono-or bis-nitrene radical complexes are formed. Reaction of [CoIII(TAMLsq)] or [CoIII(TAMLred)]- with PhINNs results in the formation of [CoIII(TAMLq)(Na¢Ns)] and [CoIII(TAMLq)(Na¢Ns)2]-, respectively. Herein, ligand-to-substrate single-electron transfer results in one-electron-reduced Fischer-type nitrene radicals (Na¢Ns-) that are intermediates in catalytic nitrene transfer to styrene. These nitrene radical species were characterized by EPR, XANES, and UV-vis spectroscopy, high-resolution mass spectrometry, magnetic moment measurements, and supporting CASSCF calculations.
- De Bruin, Bas,Oudsen, Jean-Pierre H.,Rietdijk, Niels R.,Siegler, Maxime A.,Tepaske, Martijn A.,Tromp, Moniek,Van Der Vlugt, Jarl Ivar,Van Leest, Nicolaas P.,Venderbosch, Bas
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supporting information
p. 552 - 563
(2020/02/20)
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- Organocatalytic Olefin Aziridination via Iminium-Catalyzed Nitrene Transfer: Scope, Limitations, and Mechanistic Insight
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Olefin aziridination via organocatalytic nitrene transfer offers potential complementarity to metal-catalyzed methods; however there is a lack of reports of such reactions in the literature. Herein is reported a method that employs an iminium salt to cata
- Johnson, Shea L.,Hilinski, Michael K.
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p. 8589 - 8595
(2019/07/03)
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- Intermolecular scandium triflate-promoted nitrene-transfer [5 + 1] cycloadditions of vinylcyclopropanes
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Sc(OTf)3-promoted [5 + 1] cycloaddition of vinylcyclopropanes with PhINTs is reported, enabling the regioselective preparation of a range of 1,2,3,6-tetrahydropyridine scaffolds under mild conditions. This represents the second example of a [5
- Laudenschlager, Julie E.,Combee, Logan A.,Hilinski, Michael K.
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supporting information
p. 9413 - 9417
(2019/11/14)
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- Double Functionalization of Styrenes by Cu-Mediated Assisted Tandem Catalysis
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The double functionalization of styrenes through Cu-mediated assisted tandem catalysis was developed. The reaction was initiated by Cu-catalyzed aziridination and the subsequent nucleophilic ring-opening, which was triggered by the addition of (NH4)2S2O8 as an oxidant of Cu-catalyst to form a variety of C–C and C–X bonds. The expansion to three contiguous catalytic cycles led to the synthesis of functionalized indolines by one-pot operation.
- Kawauchi, Daichi,Ueda, Hirofumi,Tokuyama, Hidetoshi
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supporting information
p. 2056 - 2060
(2019/03/13)
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- Uncatalyzed Oxidative C?H Amination of 9,10-Dihydro-9-Heteroanthracenes: A Mechanistic Study
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A new method for the one-step C?H amination of xanthene and thioxanthene with sulfonamides is reported, without the need for any metal catalyst. A benzoquinone was employed as a hydride (or two-electron and one-proton) acceptor. Moreover, a previously unknown and uncatalyzed reaction between iminoiodanes and xanthene, thioxanthene and dihydroacridines (9,10-dihydro-9-heteroanthracenes or dihydroheteroanthracenes) is disclosed. The reactions proceed through hydride transfer from the heteroarene substrate to the iminoiodane or benzoquinone, followed by conjugate addition of the sulfonamide to the oxidized heteroaromatic compounds. These findings may have important mechanistic implications for metal-catalyzed C?H amination processes involving nitrene transfer from iminoiodanes to dihydroheteroanthracenes. Due to the weak C?H bond, xanthene is an often-employed substrate in mechanistic studies of C?H amination reactions, which are generally proposed to proceed via metal-catalyzed nitrene insertion, especially for reactions involving nitrene or imido complexes that are less reactive (i.e., less strongly oxidizing). However, these substrates clearly undergo non-catalyzed (proton-coupled) redox coupling with amines, thus providing alternative pathways to the widely assumed metal-catalyzed pathways.
- van Leest, Nicolaas P.,Grooten, Lars,van der Vlugt, Jarl Ivar,de Bruin, Bas
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supporting information
p. 5987 - 5993
(2019/04/03)
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- Regiodivergent and Stereospecific Aziridine Opening by Copper-Catalyzed Addition of Silicon Grignard Reagents
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A stereospecific ring opening of various 2-aryl-substituted aziridines with silicon Grignard reagents under copper catalysis is reported. The regiochemical outcome is governed by the steric demand of the silicon nucleophile. The LiCl introduced with the m
- Yi, Hong,Oestreich, Martin
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supporting information
p. 6505 - 6507
(2019/04/30)
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- Branched Amine Synthesis via Aziridine or Azetidine Opening with Organotrifluoroborates by Cooperative Br?nsted/Lewis Acid Catalysis: An Acid-Dependent Divergent Mechanism
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A practical catalytic method to synthesize β,β- and γ,γ-substituted amines by opening aziridines and azetidines, respectively, using alkenyl, alkynyl, or aryl/heteroaryl trifluoroborate salts is described. This reaction features simple open-flask reaction conditions, the use of transition-metal-free catalysis, complete regioselectivity, and high diastereoselectivity. Preliminary mechanistic studies suggest that carbocation formation is disfavored. Stereoretentive addition is favored with Br?nsted acid present, while stereoinversion is favored in its absence, indicating divergent mechanisms.
- Nguyen, Truong N.,May, Jeremy A.
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supporting information
p. 3618 - 3621
(2018/06/26)
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- A Metal–Organic Framework with Exceptional Activity for C?H Bond Amination
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The development of catalysts capable of fast, robust C?H bond amination under mild conditions is an unrealized goal despite substantial progress in the field of C?H activation in recent years. A Mn-based metal–organic framework (CPF-5) is described that promotes the direct amination of C?H bonds with exceptional activity. CPF-5 is capable of functionalizing C?H bonds in an intermolecular fashion with unrivaled catalytic stability producing >105 turnovers.
- Wang, Le,Agnew, Douglas W.,Yu, Xiao,Figueroa, Joshua S.,Cohen, Seth M.
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supporting information
p. 511 - 515
(2018/02/21)
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- Copper-Catalyzed Aziridination with Redox-Active Ligands: Molecular Spin Catalysis
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Small-molecule catalysts as mimics of biological systems illustrate the chemists’ attempts at emulating the tantalizing abilities displayed by nature's metalloenzymes. Among these innate behaviors, spin multistate reactivity is used by biological systems as it offers thermodynamic leverage towards challenging chemical reactivity but this concept is difficult to translate into the realm of synthetic organometallic catalysis. Here, we report a rare example of molecular spin catalysis involving multistate reactivity in a small-molecule biomimetic copper catalyst applied to aziridination. This behavior is supported by spin state flexibility enabled by the redox-active ligand.
- Ren, Yufeng,Cheaib, Khaled,Jacquet, Jérémy,Vezin, Hervé,Fensterbank, Louis,Orio, Maylis,Blanchard, Sébastien,Desage-El Murr, Marine
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supporting information
p. 5086 - 5090
(2018/02/21)
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- Intermolecular Amidation of Quinoline N-Oxides with Arylsulfonamides under Metal-Free Conditions
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An efficient method for the synthesis of N-(quinolin-2-yl)sulfonamides is described. The intermolecular amidation of quinoline N-oxides with sulfonamides proceeded smoothly in the presence of PhI(OAc)2 and PPh3 to afford N-(quinolin-
- Yu, Xiaoqiang,Yang, Sana,Zhang, Yue,Guo, Mingju,Yamamoto, Yoshinori,Bao, Ming
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p. 6088 - 6091
(2017/11/27)
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- A 5 - alkyl - 2, 3 - dihydrobenzofuran - C60 The fullerene alkene pair adduct and its preparation and use
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The invention discloses a 5-alkyl-2,3-dihydrobenzofuran-C60 fullerene bis-adduct and a preparation method and application thereof. The bis-adduct as shown in the formula (I) (R is methyl or ethyl or isopropyl or tertiary butyl or tertiary pentyl) can be p
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Paragraph 0042; 0052; 0062
(2017/08/31)
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- Copper-catalyzed silylation reactions of propargyl epoxides: Easy access to 2,3-allenols and stereodefined alkenes
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Efficient silylation reactions of propargyl epoxides catalyzed by copper catalysts have been developed. Under mild reaction conditions, tri- and tetra-substituted functionalized allenols and alkenes could be selectively obtained in moderate to high yields
- Chang, Xi-Hao,Liu, Zheng-Li,Luo, Yun-Cheng,Yang, Chao,Liu, Xiao-Wei,Da, Bing-Chao,Li, Jie-Jun,Ahmad, Tanveer,Loh, Teck-Peng,Xu, Yun-He
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supporting information
p. 9344 - 9347
(2017/08/23)
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- Design, synthesis, and biological evaluation of CXCR4 ligands
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A combination of the CXCR4 inverse agonist T140 with N-terminal CXCL12 oligopeptides has produced the first nanomolar synthetic CXCR4 agonists. In these agonists, the inverse agonistic portion provides affinity whereas the N-terminal CXCL12 sequence induces receptor activation. Several CXCR4 crystal structures exist with either CVX15, an inverse agonist closely related to T140 and IT1t, a small molecule; we therefore attempted to produce another CXCL12 oligopeptide combination with IT1t. For this purpose, a primary amino group was introduced by total synthesis into one of the methyl groups of IT1t, serving as an anchoring point for the oligopeptide graft. The introduction of the oligopeptides on this analog however yielded antagonists, one compound displaying high affinity. On the other hand, the amino-substituted analogue itself proved to be an inverse agonist with a binding affinity of 2.6 nM compared to 11.5 nM for IT1t. This IT1t-like analog is hitherto one of the most potent non-peptidic CXCR4 inverse agonists reported.
- Mona, Christine E.,Besserer-Offroy, élie,Cabana, Jér?me,Leduc, Richard,Lavigne, Pierre,Heveker, Nikolaus,Marsault, éric,Escher, Emanuel
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p. 10298 - 10311
(2016/11/11)
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- Efficient and mild synthesis of substituted 2-amino-1,3,4-oxadiazoles mediated by (tosylimino)phenyl-γ3-iodane
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A simple and convenient one-pot protocol for the synthesis of substituted 2-amino-1,3,4-oxadiazoles mediated by (tosylimino)phenyl-γ3- iodane has been described. Acylthiosemicarbazides prepared from the corresponding acylhydrazides undergo effi
- Prabhu, Girish,Madhu, Chilakapathi,Sureshbabu, Vommina V.
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p. 865 - 870
(2014/08/05)
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- Gold(I)-catalyzed rearrangement of alkynylaziridine indoles for the synthesis of spiro-tetrahydro-β-carbolines
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Functionalized spiro-tetrahydro-β-carbolines were formed by an efficient gold(I)-catalyzed rearrangement reaction of alkynylaziridine indoles. The reaction involved a Friedel-Crafts type intramolecular reaction of alkynylaziridine indoles, following by hydroamination of aminoallene intermediate.
- Yang, Yan-Fang,Li, Lian-Hua,He, Yu-Tao,Luo, Jian-Yi,Liang, Yong-Min
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supporting information
p. 702 - 707
(2014/02/14)
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- Zinc chloride catalyzed ring opening of N-arylsulfonyl aziridines by thioamides: A new approach to the synthesis of amidines
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The first zinc chloride catalyzed ring opening of N-arylsulfonyl aziridines by thioamides is described. Various thioamides were reacted with N-arylsulfonyl aziridines in the presence of a catalytic amount of dry zinc chloride to provide the corresponding
- Hajibabaei, Khadijeh,Zali-Boeini, Hassan
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supporting information
p. 2044 - 2048
(2014/11/08)
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- A mild and efficient direct α-amination of β-dicarbonyl compounds using iodosobenzene and p-toluenesulfonamide catalyzed by perchlorate zinc hexahydrate
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A direct α-amination of β-dicarbonyl compounds has been achieved by using iodosobenzene (PhIO) as an oxidant and p-toluenesulfonamide (TsNH 2) as an aminating reagent in the presence of a catalytic amount of perchlorate zinc hexahydrate. The present amination reaction proceeds quickly at rt (30 min needed for most tested substrates) to provide the corresponding α-N-tosylamido β-dicarbonyl compounds in high to excellent yields.
- Yu, Jun,Liu, Shan-Shan,Cui, Jian,Hou, Xue-Sen,Zhang, Chi
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body text
p. 832 - 835
(2012/03/22)
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- HIGH-VALENT PALLADIUM FLUORIDE COMPLEXES AND USES THEREOF
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The present invention provides novel high-valent palladium complexes. The complexes typically include multi-dentate ligands that stabilize the octahedral coordination sphere of the palladium(IV) atom. These complexes are useful in fluorinating organic compounds and preparing high-valent palladium fluoride complexes. The invention is particularly useful for fluorinating compounds with 19F for PET imaging.
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Page/Page column 78-79
(2012/03/11)
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- (Tosylimino)phenyl-λ3-iodane as a reagent for the synthesis of methyl carbamates via hofmann rearrangement of aromatic and aliphatic carboxamides
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A new, mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides using (tosylimino)phenyl-λ3-iodane, PhINTs, as a reagent is reported. Because of the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides, which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates or their subsequent conversion to stable carbamates by treatment with alcohols.
- Yoshimura, Akira,Luedtke, Matthew W.,Zhdankin, Viktor V.
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experimental part
p. 2087 - 2091
(2012/05/05)
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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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- An efficient, overall [4+1] cycloadditon of 1,3-dienes and nitrene precursors
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Intermolecular cycloadditions of conjugated dienes and nitrene precursors usually produce aziridines. A generally useful method was lacking to directly provide the [4+1] cycloadducts, 3-pyrrolines. We have realized this transformation by using an uniquely active catalyst, copper(II) 1,1,1,5,5,5-hexafluoroacetylacetonate ([Cu(hfacac)2]). The method is applicable to a wide array of dienes with good yields. When 1,4-disubsituted dienes are used as substrates, good-to-excellent cis or trans selectivity can be obtained. Interestingly, the cis or trans preference depends on the nature of the substituents, rather than diene geometry. Mechanistic studies reveal that the [4+1] cycloaddition proceeds through diene aziridination and subsequent ring expansion. Among common copper catalysts, only [Cu(hfacac)2] can efficiently catalyze both steps, which explains the unique efficiency of the catalyst.
- Wu, Qiong,Hu, Jian,Ren, Xinfeng,Zhou, Jianrong
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supporting information; experimental part
p. 11553 - 11558
(2011/11/29)
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- On the enantioselectivity of aziridination of styrene catalysed by copper triflate and copper-exchanged zeolite Y: Consequences of the phase behaviour of enantiomeric mixtures of N-arene-sulfonyl-2-phenylaziridines
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By synthesising S-2-phenyl-N-(4-nitrophenyl)aziridine from S-phenylglycinol, it has been demonstrated that the aziridination of styrene by [N-(4-nitrobenzenesulfonyl)imino]phenyliodinane (nosyliminophenyliodinane, PhINNs) in the presence of S,S-2,2′-isopr
- Jeffs, Laura,Arquier, Damien,Kariuki, Benson,Bethell, Donald,Page, Philip C. Bulman,Hutchings, Graham J.
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experimental part
p. 1079 - 1084
(2011/04/12)
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- Synthesis and uses of pyroglutamic acid derivatives
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Novel pyroglutamic acid derivatives (I), wherein R1 is -OH, -ORa, wherein Ra is alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, aralkyl or heterocyclyl; R2, R3 and R4 are independently H, a nitrogen protecting group which hydrolyzes under acidic conditions or phtalamide; X is a pharmaceutically acceptable anion; and Y is a N-containing group; either in the form of their isolated optically active stereoisomers or in the form of mixtures thereof, are useful compounds for enhancing an immuneresponse in a subject and/or for treating tumours, bacterial, fungal or viral infections, or autoimmune diseases.
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Page/Page column 29
(2008/06/13)
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- NOVEL THIOPHENE SULFOXIMINES FOR TREATING COMPLEMENT-MEDIATED DISEASES AND CONDITIONS
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Disclosed are compounds for treating the symptoms of an acute or chronic disorder mediated by the classical pathway of the complement cascade. Said compounds are of Formula I I or a solvate, hydrate, pharmaceutically acceptable salt, or prodrug thereof; wherein Ra, Rb, and Rc are defined in the specification, as are A Z, Q, R1 and R2.
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Page/Page column 91
(2008/06/13)
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- Catalytic asymmetric heterogeneous aziridination of styrene using CuHY: Effect of nitrene donor on enantioselectivity
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The copper-catalysed aziridination of styrene with copper-exchanged zeolite Y (CuHY) and copper(II) triflate (trifluoromethanesulfonate) (Cu(OTf)2) as catalysts is described in detail. Two nitrene donors, [N-(p-tolylsulfonyl)imino)]phenyliodinane (PhI=NTs) and [N-(p-nitrophenylsulfonyl)imino]phenyliodinane (PhI=NNs) are compared. Modification of the catalyst with bis(oxazolines) affords enantioselective catalysts and a range of chiral bis-(oxazolines) has been studied. The ratio of nitrene donor to styrene is shown to be an important factor controlling both the yield and ee of aziridine formed. The best results are obtained with PhI=NNs; ee, ≥ 90%, together with high yields (≥ 85%), can readily be achieved with this nitrene donor using acetonitrile as solvent. Addition of the nitrene donor over a period of time, rather than all at the start of the reaction, is shown to enhance the yield of the aziridine but the ee is significantly decreased for both the homogeneous and the heterogeneous catalysts. Experiments in which the breakdown products of the nitrene donor, iodobenzene and the corresponding sulfonamide, are added at the star of the reaction show that a complex interplay exists at the copper active site between the reactants, products, chiral modifier and the solvent. However, the heterogeneous catalyst, CuHY, is found to give enhanced enantioselection for a range of bis(oxazolines) compared to the homogeneous catalyst, and the effect is considered to be due to the confinement of the catalyst within the micropores of the zeolite.
- Taylor, Sophia,Gullick, John,McMorn, Paul,Bethell, Donald,Page, Philip C. Bulman,Hancock, Frederick E.,King, Frank,Hutchings, Graham J.
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p. 1714 - 1723
(2007/10/03)
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- Planar chirality: Cycloaddition and transannular reactions of optically active azoninones that contain (E)-olefins
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Unsaturated nine-membered ring lactams that contain (E)-olefins within the ring are characterized by planar chiral properties. Thus, selective conversions of the double bond allowed a complete transfer of the planar chiral information into new stereogenic
- Sudau, Alexander,Muench, Winfried,Bats, Jan W.,Nubbemeyer, Udo
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p. 611 - 621
(2007/10/03)
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- Preparation and evaluation of nitrene precursors (PhI=NSO2Ar) for the copper-catalyzed aziridination of olefins
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The preparation of different [N-(arenesulfonyl)imino]phenyliodinanes is described along with an evaluation of their utility as nitrene precursors for the copper-catalyzed aziridination of different olefins. The best results were obtained with p-NO2/
- Soedergren, Mikael J.,Alonso, Diego A.,Bedekar, Ashutosh V.,Andersson, Pher G.
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p. 6897 - 6900
(2007/10/03)
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- Asymmetric C-N bond constructions via crotylsilane addition reactions: A stereocontrolled route to dipeptide isosteres
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A new approach to the asymmetric synthesis of (E)-olefin dipeptide isosteres is described based on asymmetric C-N bond constructions resulting from nitronium tetrafluoroborate (NO2BF4) promoted electrophilic nitrations of chiral (E)-crotylsilanes and from a copper(I)-catalyzed enantioselective aziridination of chiral (E)-crotylsilanes. The silane reagents undergo efficient anti-S(E)' additions to the nitrogen-based electrophiles to give the (E)-olefin isosteves in > 96% de. The topological bias is principally controlled by the facial bias of the silane reagent. The scope of the methodology was explored via several related crotylsilane derivatives. The (E)-olefin isosteres are nonhydrolyzable, rigid analogs of the peptide linkage in biologically active peptides. The new methodology will facilitate the preparation and study of peptidomimetics since the crotylsilane reagents allow for incorporation of a wide range of functionality on the resulting isosteres.
- Masse, Craig E.,Knight, Bradford S.,Stavropoulos, Pericles,Panek, James S.
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p. 6040 - 6047
(2007/10/03)
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- Catalytic Asymmetric Sulfimidation
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A direct catalytic imidation of sulfides to sulfimides with [N-(p-tolylsulfonyl)imino]phenyliodinane (TsN=IPh) using a catalytic amount of copper triflate (CuOTf) has been developed. The reaction proceeds with a wide range of sulfides to give the corresponding sulfimides in 50-83% isolated yields. When the reaction is applied to allylic sulfides, the products are the corresponding sulfonamides produced via [2,3] sigmatropic rearrangement of the initially formed allylic sulfimides. In the presence of a chiral bis(oxazoline) as ligand, asymmetric induction occurs to afford the chiral sulfimides (up to 71% ee) and sulfonamides (up to 58% ee). Chloramine T (TsNClNa) can be used in place of TsN=IPh for asymmetric sulfimidation, but the ee's are much lower. Some mechanistic observations are described.
- Takada, Hiroya,Nishibayashi, Yoshiaki,Ohe, Kouichi,Uemura, Sakae,Baird, Charlotte P.,Sparey, Tim J.,Taylor, Paul C.
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p. 6512 - 6518
(2007/10/03)
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- A new method for the preparation of (arylsulfonyliminoiodo)benzenes
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(Arylsulfonyliminoiodo)benzenes (3) can be prepared in 52-92% yield via the reaction of dimethoxyiodobenzene (1) with the corresponding arylsulfonamide in MeOH or CH2Cl2 at room temperature.
- Besenyei, Gabor,Nemeth, Sandor,Simandi, Laszlo I.
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p. 6105 - 6106
(2007/10/02)
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- Aziridination of Alkenes catalysed by Porphyrinirons: Selection of Catalysts for Optimal Efficiency and Stereospecificity
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meso-Tetra-arylporphyriniron(III) derivatives catalyse the N-tosylaziridination of aryl-substituted styrenes by tosylimidoiodobenzene, PhINTs, a nitrogen analogue of iodosylbenzene.Three secondary reactions were found to limit the yield of N-tosylaziridination: (i) the formation of toluene-p-sulphonamide, TsNH2, which is presumably derived from hydrolysis of a possible iron-nitrene, Fe=NTs, intermediate, (ii) the conversion of the Fe(TPP)(Cl) (TPP = tetraphenylporphyrin) catalyst into an iron(III) complex where the NTs moiety is inserted into an iron-nitrogen bond of Fe(TPP)(Cl), (iii) an oxidative degradation of the porphyrin catalyst.These secondary reactions were avoided to a great extent by using anhydrous conditions and Fe(TDCPP)(ClO4) (TDCPP = tetrakis-2,6-dichlorophenylporphyrin) as a catalyst instead of Fe(TPP)(Cl) and Fe(TPP)(ClO4).Under these conditions, N-tosylaziridination of styrene, cis- and trans-stilbene, and 1,1-diphenylethylene was performed with yields between 40 and 90percent.Fe(TDCPP)(ClO4) was also found to be the best catalyst for N-tosylaziridination of aliphatic alkenes such as hex-1-ene, cyclo-octene, and cis- and trans-hex-2-enes.Although N-tosylaziridination of the two latter alkenes catalysed by Fe(TPP)(Cl) was not stereospecific, this reaction became stereospecific with Fe(TDCPP)(ClO4) as catalyst.These results show that by a proper choice of the porphyriniron catalyst, relatively good yields of N-tosylaziridination of alkenes by PhINTs can be obtained.As for 1,2-disubstituted aliphatic alkenes, syn addition of the NTs moiety to the double bond takes place.A possible mechanism is presented.
- Mahy, Jean-Pierre,Bedi, Gustave,Battioni, Pierrette,Mansuy, Daniel
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p. 1517 - 1524
(2007/10/02)
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- Aliphatic hydroxylation by cytochrome P-450. Evidence for rapid hydrolysis of an intermediate iron-nitrene complex
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Studies with synthetic metalloporphyrin-based hydrocarbon oxidation systems have suggested that the cytochrome P-450 class of heme-containing enzymes may be able to transfer a nitrene equivalent to a hydrocarbon substrate in direct analogy to their currently known ability to transfer an oxene equivalent. Exposure of cyclohexane to the nitrenoid reagent (N-(p-toluenesulfonyl)imino)phenyliodinane in the presence of a purified cytochrome P-450 isozyme (P-450(LM2)) did not result in any amidation of the hydrocarbon. Instead, cyclohexane was efficiently hydroxylated to cyclohexanol. Hydroxylation was also observed with two other hydrocarbons, methylcyclohexane and p-xylene. This reaction is a true catalytic activity of the P-450. Anaerobic and isotope-labeling studies demonstrated that the oxygen in cyclohexanol derived from the water of the reaction medium. These results are interpreted by a scheme whereby the nitrenoid reagent generates a transient iron(V)-nitrene complex which is rapidly hydrolyzed in the aqueous environment to the corresponding iron(V)-oxo complex, which then hydroxylates the substrate. Studies with synthetic metallporphyrin-based hydrocarbon oxidation systems have suggested that the cytochrome P-450 class of heme-containing enzymes may be able to transfer a nitrene equivalent to a hydrocarbon substrate in direct analogy to their currently known ability to transfer an oxene equivalent. Exposure of cyclohexane to the nitrenoid reagent (N-(p-toluenesulfonyl)imino) phenyliodinane in the presence of a purified cytochrome P-450 isozyme (P-450//L//M//2) did not result in any amidation of the hydrocarbon. Instead, cyclohexane was efficiently hydroxylated to cyclohexanol.
- White,McCarthy
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p. 4922 - 4926
(2007/10/02)
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