- Enantioselective Intermolecular C-H Amination Directed by a Chiral Cation
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The enantioselective amination of C(sp3)-H bonds is a powerful synthetic transformation yet highly challenging to achieve in an intermolecular sense. We have developed a family of anionic variants of the best-in-class catalyst for Rh-catalyzed C-H amination, Rh2(esp)2, with which we have associated chiral cations derived from quaternized cinchona alkaloids. These ion-paired catalysts enable high levels of enantioselectivity to be achieved in the benzylic C-H amination of substrates bearing pendant hydroxyl groups. Additionally, the quinoline of the chiral cation appears to engage in axial ligation to the rhodium complex, providing improved yields of product versus Rh2(esp)2 and highlighting the dual role that the cation is playing. These results underline the potential of using chiral cations to control enantioselectivity in challenging transition-metal-catalyzed transformations.
- Fanourakis, Alexander,Paterson, Kieran J.,Phipps, Robert J.,Williams, Benjamin D.
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supporting information
p. 10070 - 10076
(2021/07/21)
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- Ruthenium-catalyzed ester reductions applied to pharmaceutical intermediates
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Ruthenium pincer complexes were synthesized and used for catalytic ester reductions under mild conditions (~5 bar of hydrogen). An experimental design approach was used to optimize the conditions for yield, purity, and robustness. Evidence for the catalytically active ruthenium dihydride species is presented. Observed intermediates and side products, as well as time-course data, were used to build mechanistic insight. The optimized procedure was further demonstrated through scaled-up reductions of two pharmaceutically relevant esters, both in batch and continuous flow.
- Shaalan, Youssef,Boulton, Lee,Jamieson, Craig
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supporting information
p. 2745 - 2751
(2020/11/30)
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- Novel bi-halogenated acetylated heterocyclic pyrethroid and preparation and application methods thereof
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The invention relates to the technical field of medicines, particularly to a novel bi-halogenated acetylated heterocyclic pyrethroid and preparation and application methods thereof. The novel bi-halogenated acetylated heterocyclic pyrethroid has a chemical structural formula shown as the formula I. The preparation method of the novel bi-halogenated acetylated heterocyclic pyrethroid comprises thefollowing steps of, firstly, reducing methyl m-iodobenzoate with LiBH4 to obtain m-iodobenzyl alcohol; secondly, mixing dimethylcyclopropane carboxylic acid, oxalyl chloride, N, N-dimethyl formamide and the m-iodobenzyl alcohol for mixed reaction to obtain DCA-O (dimethylcyclopropane carboxylate) compounds; thirdly, through Suzuki coupling, subjecting the DCA-O prepared in the second step, PdCl2(dppf), K3PO4 and boric acid to reaction to obtain the novel bi-halogenated acetylated heterocyclic pyrethroid. The novel bi-halogenated acetylated heterocyclic pyrethroid is applied as a mosquito growth inhibiting pesticide. The novel bi-halogenated acetylated heterocyclic pyrethroid and the preparation and application methods thereof solve the technical problem that pyrethroid pesticides in the prior art cannot integrate mosquito killing activity and pesticide resistance.
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Paragraph 0027; 0028
(2019/05/02)
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- Rapid and efficient copper-catalyzed finkelstein reaction of (hetero)aromatics under continuous-flow conditions
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A general, rapid, and efficient method for the copper-catalyzed Finkelstein reaction of (hetero)aromatics has been developed using continuous flow to generate a variety of aryl iodides. The described method can tolerate a broad spectrum of functional groups, including N-H and O-H groups. Additionally, in lieu of isolation, the aryl iodide solutions were used in two distinct multistep continuous-flow processes (amidation and Mg-I exchange/nucleophilic addition) to demonstrate the flexibility of this method.
- Chen, Mao,Ichikawa, Saki,Buchwald, Stephen L.
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supporting information
p. 263 - 266
(2015/02/05)
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- Ortho-stabilized 18F-azido click agents and their application in PET imaging with single-stranded DNA aptamers
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Azido 18F-arenes are important and versatile building blocks for the radiolabeling of biomolecules via Huisgen cycloaddition ("click chemistry") for positron emission tomography (PET). However, routine access to such clickable agents is challenged by inefficient and/or poorly defined multistep radiochemical approaches. A high-yielding direct radiofluorination for azido 18F-arenes was achieved through the development of an ortho-oxygen-stabilized iodonium derivative (OID). This OID strategy addresses an unmet need for a reliable azido 18F-arene clickable agent for bioconjugation reactions. A ssDNA aptamer was radiolabeled with this agent and visualized in a xenograft mouse model of human colon cancer by PET, which demonstrates that this OID approach is a convenient and highly efficient way of labeling and tracking biomolecules. Markedly apt: A high-yielding direct radiofluorination strategy via ortho-oxygen-substituted iodonium derivatives is described. A ssDNA aptamer (sgc8), labelled with the resulting 18F azido agent through click chemistry, was used for PET imaging and provides the first example for the noninvasive in vivo PET imaging of protein tyrosine kinase 7 (PTK-7).
- Wang, Lu,Jacobson, Orit,Avdic, Din,Rotstein, Benjamin H.,Weiss, Ido D.,Collier, Lee,Chen, Xiaoyuan,Vasdev, Neil,Liang, Steven H.
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supporting information
p. 12777 - 12781
(2015/10/28)
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- Novel preparation of polymer-supported iodobenzene and its synthetic utility as a recyclable reagent with m-chloroperbenzoic acid
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Three novel polymer-supported iodobenzene compounds A0, A 6, and A10 were prepared from the reaction of commercially available cross-linked poly(p-chloromethyl)styrene with m-iodobenzylalcohol, 6-(m-iodobenzyloxy)-1-hexanol, and 10-(m-iodobenzyloxy)-1-decanol. Their catalytic reactivity and reusability for the oxidative α-tosyloxylation of ketones and the cyclization of N-methoxy-2-arylethanesulfonamides in the presence of m-chloroperbenzoic acid (mCPBA) were confirmed to provide -tosyloxyketones and N-methoxy-3,4-dihydro-2,1-benzothiazine-2,2-dioxides, respectively, in good yields. Georg Thieme Verlag Stuttgart · New York.
- Suzuki, Yuhsuku,Togo, Hideo
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body text
p. 2355 - 2360
(2010/09/18)
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- Self-assembly of shape-persistent hexagonal macrocycles with trimeric bis(terpyridine)-FeII connectivity
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A novel family of bis(terpyridinyl) ligands was designed and constructed by facile Pd-catalyzed coupling reactions. Subsequent terpyridine-transition-metal complexation facilitated self-assembly resulting in a hexagonal, trimeric series of metallomacrocycles. An enhanced solubility of a macrocycle and its bis(terpyridine) precursor possessing elongated, alkyl-branched phenylacetylene spacers was achieved by the incorporation of dodecyloxy moieties. The characterization of the metallomacrocycles included 1H, 13C NMR, and UV spectroscopy and mass spectrometry, as well as electrochemistry. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Li, Sinan,Moorefield, Charles N.,Wang, Pingshan,Shreiner, Carol D.,Newkome, George R.
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experimental part
p. 3328 - 3334
(2009/04/06)
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- CELL TARGETING CONJUGATES
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The present invention relates to cell targeting conjugates and in particular, but not exclusively, to methods of their use in selectively eliminating and in selectively imaging target cells. The invention also relates to processes for production of the conjugates and to intermediate compounds that may be used in production of a specific class of cell targeting conjugates. In one embodiment there is provided a cell targeting conjugate comprising the following components that are covalently conjugated via a linker that is degradable within the target cells: i) a DNA minor groove binding ligand incorporating an effective Auger electron-emitting and/or gamma-emitting and/or positron-emitting atom or photoactive moiety; ii) a target cell specific protein or peptide that is capable of internalisation by target cells.
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Page/Page column 41
(2008/06/13)
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- NOVEL LIGANDS THAT ARE ANTAGONISTS OF RAF RECEPTORS, PROCESS FOR PREPARING THEM AND USE THEREOF IN HUMAN MEDICINE AND IN COSMETICS
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The invention relates to novel compounds corresponding to formula (I) below: and to the method for preparing them, and to their use in pharmaceutical compositions intended for use in human or veterinary medicine, or alternatively in cosmetic compositions.
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- Pd-mediated C-C and C-S bond formation on solid support: A scope and limitations study
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The scope and limitations of Pd(0)-mediated coupling reactions between aromatic halides linked to a polystyrene resin and boronic acid derivatives (Suzuki coupling), aromatic and vinylic tin compounds (Stille coupling), as well as thiols are reported. For all reactions, conditions were optimized and evaluated with various reagents. In many cases, upon cleavage from the solid support, products were obtained in excellent yields. In most cases, the optimized reaction conditions are superior to those previously reported in the literature.
- Wendeborn, Sebastian,Berteina, Sabine,Brill, Wolfgang K.-D.,De Mesmaeker, Alain
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p. 671 - 675
(2007/10/03)
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- Pd- mediated C-C bond formation with olefins and acetylenes on solid support: A scope and limitations study
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In this paper we report the scope and limitations of Pd(0)-mediated coupling reactions between aromatic iodides linked to a polystyrene resin and terminal acetylenes and olefins (Heck reactions). Optimized reaction conditions were evaluated with a number of different reagents. The optimized reaction conditions were frequently found to be superior to those previously reported in the literature and resulted in excellent yields of the products upon cleavage from the solid phase.
- Berteina, Sabine,Wendeborn, Sebastian,Brill, Wolfgang K.-D.,De Mesmaeker, Alain
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p. 676 - 678
(2007/10/03)
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