- Acridine Orange Hemi(Zinc Chloride) Salt as a Lewis Acid-Photoredox Hybrid Catalyst for the Generation of α-Carbonyl Radicals
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A readily accessible organic-inorganic hybrid catalyst is reported for the reductive fragmentation of α-halocarbonyl compounds. The robust hybrid catalyst is a self-stabilizing combination of ZnCl2 Lewis acid and acridine orange as the photoactive organic dye. Mechanistic specifics of this hybrid catalyst have been studied in detail using both photophysical and electrochemical experiments. A systematic study enabled the discovery of the appropriate Lewis acid for the effective LUMO stabilization of α-halocarbonyl compounds and thereby lowering of reduction potential within the range of a standard organic dye. This strategy resolves the issues like dehalogenative hydrogenation or homo-coupling of alkyl radicals by guiding the photoredox cycle through an oxidative quenching pathway. The cooperativity between the photoactive organic dye and the Lewis acid counterparts empowers functionalization with a wide range of coupling partners through efficient and controlled generation of alkyl radicals and serves as an appropriate alternative to the expensive late transition metal-based photocatalysts. To demonstrate the application potential of this cooperative catalytic system, four different synthetic transformations of α-carbonyl bromides were explored with broad substrate scopes.
- Das, Sanju,De Sarkar, Suman,Mandal, Tanumoy
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supporting information
(2021/12/10)
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- Regio- and Stereoselective Nickel-Catalyzed Coupling of Boronic Acids with Allenoates
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The Ni(II)-catalyzed cross-coupling of arylboronic acids with allenoates is documented. The high regio- and stereoselectivity of the process enables a wide range of β-aryl β,γ-unsaturated esters to be prepared in good to excellent yields (up to 95%) and high E / Z -selectivity. Additionally, [3+2]-cascade sequence was observed when 2-formylphenylboronic acid was employed.
- Liu, Yang,Daka, Mario,Bandini, Marco
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p. 3187 - 3196
(2018/08/17)
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- Synthesis of [13C3]-B6 vitamers labelled at three consecutive positions starting from [13C3]-propionic acid
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[13C3]-labelled vitamers (PN, PL and PM) of the B6 group were prepared starting from [13C3]-propionic acid. [13C3]-PN was synthesized in ten linear steps with an overall yield of 17%. Hereby, higher alkyl homologues of involved esters showed a positive impact on the reaction outcome of the intermediates in the chosen synthetic route. Oxidation of [13C3]-PN to [13C3]-PL was undertaken using potassium permanganate and methylamine followed by acid hydrolysis of the imine derivative. [13C3]-PM could be prepared from the oxime derivative of [13C3]-PN by hydrogenation with palladium.
- Bachmann, Thomas,Rychlik, Michael
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- Prototypic 18F-Labeled Argininamide-Type Neuropeptide Y Y1R Antagonists as Tracers for PET Imaging of Mammary Carcinoma
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The neuropeptide Y (NPY) Y1 receptor (Y1R) selective radioligand (R)-Nα-(2,2-diphenylacetyl)-Nω-[4-(2-[18F]fluoropropanoylamino)butyl]aminocarbonyl-N-(4-hydroxybenzyl)argininamide ([18F]23), derived from the high-affinity Y1R antagonist BIBP3226, was developed for imaging studies of Y1R-positive tumors. Starting from the argininamide core bearing amine-functionalized spacer moieties, a series of fluoropropanoylated and fluorobenzoylated derivatives was synthesized and studied for Y1R affinity. The fluoropropanoylated derivative 23 displayed high affinity (Ki = 1.3 nM) and selectivity toward Y1R. Radiosynthesis was accomplished via 18F-fluoropropanoylation, yielding [18F]23 with excellent stability in mice; however, the biodistribution study revealed pronounced hepatobiliary clearance with high accumulation in the gall bladder (>100 %ID/g). Despite the unfavorable biodistribution, [18F]23 was successfully used for imaging of Y1R positive MCF-7 tumors in nude mice. Therefore, we suggest [18F]23 as a lead for the design of PET ligands with optimized physicochemical properties resulting in more favorable biodistribution and higher Y1R-dependent enrichment in mammary carcinoma.
- Keller, Max,Maschauer, Simone,Brennauer, Albert,Tripal, Philipp,Koglin, Norman,Dittrich, Ralf,Bernhardt, Günther,Kuwert, Torsten,Wester, Hans-Jürgen,Buschauer, Armin,Prante, Olaf
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supporting information
p. 304 - 309
(2017/03/17)
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- Regio- and Stereoselective Copper(II)-Catalyzed Hydrosilylation of Activated Allenes in Water: Access to Vinylsilanes
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By using catalytic amounts of copper(II), 4-picoline, and dimethylphenylsilylpinacol borane, a series of allenoates were silylated on the β carbon in good to excellent yields and high (E)-selectivity. The mild and efficient silylation method is conducted in water under atmospheric conditions to afford vinylsilanes.
- Pashikanti, Srinath,Calderone, Joseph A.,Nguyen, Matthew K.,Sibley, Christopher D.,Santos, Webster L.
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supporting information
p. 2443 - 2446
(2016/06/09)
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- Cobalt-bisoxazoline-catalyzed asymmetric kumada cross-coupling of racemic α-bromo esters with aryl grignard reagents
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The first cobalt-catalyzed asymmetric Kumada cross-coupling with high enantioselectivity has been developed. The reaction affords a unique strategy for the enantioselective arylation of α-bromo esters catalyzed by a cobalt-bisoxazoline complex. A variety of chiral α-arylalkanoic esters were prepared in excellent enantioselectivity and yield (up to 97% ee and 96% yield). The arylated products were transformed into α-arylcarboxylic acids and primary alcohols without erosion of ee. The new enantioenriched α-arylpropionic esters synthesized herein are potentially useful in the development of nonsteroidal anti-inflammatory drugs. This method was conducted on gram-scale and applied to the synthesis of highly enantioenriched (S)-fenoprofen and (S)-ar-turmerone.
- Mao, Jianyou,Liu, Feipeng,Wang, Min,Wu, Lin,Zheng, Bing,Liu, Shangzhong,Zhong, Jiangchun,Bian, Qinghua,Walsh, Patrick J.
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supporting information
p. 17662 - 17668
(2015/02/02)
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- Highly selective synthesis of α-bromoesters using molecular bromine catalyzed by phosphorus
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A series of α-bromoesters have been synthesized by applying Hell-Volhard-Zelinsky reaction catalyzed by phosphorus instead of usual phosphorus tribromide. An excellent regioselectivity to good yields are achieved at comparatively mild reaction conditions of an operational simplicity.
- Sun, Zhaoyun,Peng, Xinhua,Dong, Xiongzi,Shi, Wenwen
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experimental part
p. 929 - 930
(2012/07/30)
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- COMPOUNDS USEFUL AS INHIBITORS AS AMPK
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According to the invention there is provided a compound of formula (I), wherein, X, T, Y1, E, M, A1 to A5 and D1 to D5 have meanings given in the description, which compounds are useful in the treatment of cancer
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Page/Page column 39
(2010/08/09)
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- Free radical trapping properties of several ethyl-substituted derivatives of 5-ethoxycarbonyl-5-methyl-1-pyrroline N-oxide (EMPO)
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The spin trapping behavior of several ethyl-substituted EMPO derivatives, cis- and trans-5-ethoxycarbonyl-3-ethyl-5-methyl-pyrroline N-oxide (3,5-EEMPO), 5-ethoxycarbonyl-4-ethyl-5-methyl-pyrroline N-oxide (4,5-EEMPO), cis- and trans-5-ethoxycarbonyl-5-ethyl-3-methyl-pyrroline N-oxide (5,3-EEMPO), and 5-ethoxycarbonyl-5-ethyl-4-methyl-pyrroline N-oxide (5,4-EEMPO), toward a series of different oxygen- and carbon-centered radicals, is described. Considerably different stabilities of the superoxide adducts (ranging from about 12 to 55 min) as well as the formation of other radical adducts were observed.
- Stolze, Klaus,Rohr-Udilova, Natascha,Rosenau, Thomas,Hofinger, Andreas,Nohl, Hans
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p. 2827 - 2836
(2007/10/03)
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- Inclusion complexes of EMPO derivatives with 2,6-di-O-methyl-β- cyclodextrin: Synthesis, NMR and EPR investigations for enhanced superoxide detection
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The free radical trapping properties of eight 5-alkoxycarbonyl-5-methyl-1- pyrroline N-oxide (EMPO) type nitrones and those of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) were evaluated for trapping of superoxide anion radicals in the presence of 2,6-di-O-methyl-β-cyclodextrin (DM-β-CD). 1H-NMR titrations were performed to determine both stoichiometries and binding constants for the diamagnetic nitrone-DM-β-CD equilibria. EPR titrations were then performed and analyzed using a two-dimensional EPR simulation program affording 1: 1 and 1: 2 stoichiometries for the nitroxide spin adducts with DM-β-CD and the associated binding constants after spin trapping. The nitroxide spin adducts associate more strongly with DM-β-CD than the nitrones. The ability of the nitrones to trap superoxide, the enhancement of the EPR signal intensity and the supramolecular protection by DM-β-CD against sodium l-ascorbate reduction were evaluated. The Royal Society of Chemistry 2006.
- Bardelang, David,Rockenbauer, Antal,Karoui, Hakim,Finet, Jean-Pierre,Biskupska, Inga,Banaszak, Karol,Tordo, Paul
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p. 2874 - 2882
(2008/02/08)
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- Very stable superoxide radical adducts of 5-ethoxycarbonyl-3,5-dimethyl- pyrroline N-oxide (3,5-EDPO) and its derivatives
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Oxygen radicals are involved in the onset of many diseases. Adequate spin traps are required for identification and localisation of free radical formation in biological systems. Superoxide spin adducts with half-lives up to 20 min at physiological pH have recently been reported to be formed from derivatives of the spin trap 5-ethoxycarbonyl-5-methyl-1-pyrroline N-oxide (EMPO). This is a major improvement over DMPO (t1/2 ca. 45 s), and even DEPMPO (t 1/2 ca. 14 min). In this study, an additional methyl group was introduced into position 3 or 4 of the pyrroline ring which greatly increases the stability of the respective superoxide spin adducts. In addition, the ethoxy group of EMPO was exchanged by either a propoxy- or an iso-propoxy group in order to test the influence of increasing lipophilic properties of the investigated spin traps. The structure of all compounds was confirmed by 1H and 13C-NMR with full signal assignment. In comparison with EMPO (t1/2 ca. 8 min) or DEPMPO (t1/2 ca. 14 min), the superoxide adducts of all novel spin traps were considerably higher (t 1/2 ca. 12-55 min). In addition, various other spin adducts obtained from oxygen-centered as well as carbon-centered radicals (e.g. derived from methanol or linoleic acid hydroperoxide) were also detected.
- Stolze, Klaus,Rohr-Udilova, Natascha,Rosenau, Thomas,Stadtmueller, Roswitha,Nohl, Hans
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p. 1351 - 1361
(2007/10/03)
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- INHIBITORS OF HUMAN TUMOR-EXPRESSED CCXCKR2
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Pharmaceutical compositions containing organic compounds or salts thereof that serve as modulators for the SDF-1 or I-TAC chemokines are disclosed. The compounds and compositions are useful in the treatment of cancer, especially in the inhibition of cancer proliferation, growth, and metastasis. Methods of interfering with SDF-1 and/or I-TAC binding to the CCXCKR2 receptor and treating cancer using the compounds and pharmaceutical compositions of the present invention are also disclosed.
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- Azulene derivatives
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The invention provides novel azulene derivatives of general formula I wherein R1 to R6 have the significance given in the description, as well as their tautomers, enantiomers, diastereomers, racemates and physiologically compatible salts or esters and substances which are hydrolyzed or metabolized in vivo to compounds of formula I. The invention is also concerned with a process and intermediates for the manufacture of the above compounds, pharmaceutical compositions which contain such compounds as well as the use of these compounds in the treatment of inflammatory conditions.
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- Arylcyclobutylmethylamines
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Compounds of formula I STR1 and pharmaceutically acceptable salts thereof; in which R1 and R2, which are the same or different, are H or an optionally substituted hydrocarbon group or R1 and R2 together with the nitrogen atom to which they are attached form an optionally substituted heterocyclic ring; R3 is an optionally substituted aromatic hydrocarbon group; and R4 is a hydrocarbon group containing at least one substituent selected from the group consisting of hydroxy and acylated derivatives thereof, optionally substituted alkoxy groups, optionally substituted cycloalkyloxy groups, optionally substituted alkylenedioxy groups, oxo and groups of formula S(O)p R5 in which p is 0, 1 or 2 and R5 is an alkyl group, said hydrocarbon group being optionally substituted by additional substituents, are useful in the treatment of depression.
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- Specific esterase activity of subtilisin toward esters of α-haloacids
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Esters of α-haloacids are specific substrates for subtilisin which catalyses their hydrolysis in aqueous media. The same esters undergo transesterifications in organic solvents in the presence of subtilisin immobilized on an alumina-phosphate complex.
- Pugniere,Juan, C. San,Previero
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p. 4883 - 4886
(2007/10/02)
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- Resolution of racemic mixtures of aliphatic acid esters
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Racemic mixtures of partially water-soluble esters defined by the formula STR1 wherein R and R1 represent hydrogen and C1 -C4 alkyl; R2 represents C1 -C4 alkyl and X represents halogen, aliphatic or aromatic groups and substituted derivatives thereof wherein R, R1 and X are different can be resolved by reducing the water solubility of a racemic mixture of said esters by means other than changing the chemical composition of the ester, contacting the racemic mixture of esters of reduced water solubility with a lipase enzyme from Candida cylindracea capable of stereospecifically resolving the racemic mixture of hydrolysis and stereospecifically resolving the racemic mixture.
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- Phenoxyphenyl phosphinates
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Novel phenoxy-, phenylthio, anilino-, benzyl-, pyridyloxy-, pyridylthio-, pyridylamino-, or pyridylmethyl-phenyl substituted phosphinates and phosphinothioates, synthesis thereof, intermediates therefore, and the use of said novel compounds for the control of weeds.
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- Alkyl alkanoate derivatives of substituted piperazine-diones and polymer compositions stabilized thereby
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Alkyl alkanoate derivatives of substituted piperazinediones are stabilizers for synthetic polymeric materials normally subject to deterioration caused by ultraviolet light. The compounds may be formed by reacting a substituted piperazinedione with an acrylate or a crotonate, or reacting the alkali or alkaline earth salt of a substituted piperazine dione with a haloalkanoate. Polymeric compositions containing these stabilizers may also contain a hindered phenolic compound. A typical embodiment is n-octadecyl-β-(15{7,15-diazadispiro[5,1,5,3]hexadecane-14,16-dione}propionate.
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