- Mechanism of Cu-catalyzed aryl boronic acid halodeboronation using electrophilic halogen: Development of a base-catalyzed iododeboronation for radiolabeling applications
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An investigation into the mechanism of Cu-catalyzed aryl boronic acid halodeboronation using electrophilic halogen reagents is reported. Evidence is provided to show that this takes place via a boronate-driven ipso-substitution pathway and that Cu is not required for these processes to operate: General Lewis base catalysis is operational. This in turn allows the rational development of a general, simple, and effective base-catalyzed halodeboronation that is amenable to the preparation of 125I-labeled products for SPECT applications.
- Molloy, John J.,O'rourke, Kerry M.,Frias, Carolina P.,Sloan, Nikki L.,West, Matthew J.,Pimlott, Sally L.,Sutherland, Andrew,Watson, Allan J. B.
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supporting information
p. 2488 - 2492
(2019/04/10)
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- Late stage iodination of biologically active agents using a one-pot process from aryl amines
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A simple and effective one-pot tandem procedure that generates aryl iodides from readily available aryl amines via stable diazonium salts has been developed. The operationally simple procedure and mild conditions allow late-stage iodination of a wide range of aryl compounds bearing various functional groups and substitution patterns. A novel synthetic strategy involving the preparation of nitroaryl compounds followed by a chemoselective tin(ii) dichloride reduction and the use of the one-pot diazotisation-iodination transformation was also developed. The general applicability of this approach was demonstrated with the preparation of a number of medicinally important compounds including CNS1261, a SPECT imaging agent of the N-methyl-d-aspartate (NMDA) receptor and IBOX, a compound used to detect amyloid plaques in the brain.
- Sloan, Nikki L.,Luthra, Sajinder K.,McRobbie, Graeme,Pimlott, Sally L.,Sutherland, Andrew
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p. 54881 - 54891
(2017/12/12)
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- Highly chemoselective and versatile method for direct conversion of carboxylic acids to ketones utilizing zinc Ate complexes
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Various carboxylic acids were directly transformed into the corresponding ketones by utilizing organozinc ate complexes, which provide high chemoselectivity without any overreaction to the undesired tertiary carbinol, owing to formation of a stable tetrahedral zincioketal intermediate. This method offers good overall atom/step/pot economy and operational simplicity. No need to overreact: Various carboxylic acids were directly transformed to the corresponding ketones by utilizing organozinc ate complexes, which provide high chemoselectivity without any overreaction to undesired tertiary carbinol, owing to formation of a stable tetrahedral zincioketal intermediate. This method offers good overall atom/step/pot economy and operational simplicity.
- Murata, Ryo,Hirano, Keiichi,Uchiyama, Masanobu
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supporting information
p. 1286 - 1290
(2015/06/08)
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- Candida tenuis xylose reductase catalysed reduction of acetophenones: The effect of ring-substituents on catalytic efficiency
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The catalytic efficiencies of Candida tenuis xylose reductase catalysed reductions of mono-substituted acetophenones are in reasonable correlation with the σ-Hammett coefficients of the substituted phenyl groups. Variations of the substrate transformation rates are hence mainly caused by mesomeric and inductive effects of the substituents, while differences in substrate binding have a secondary relevance. Some substrate 1H NMR chemical shifts and carbonyl IR absorption bands are in reasonable accordance with the catalytic activities and allow the estimation of the transformation rates with good accuracy. The resulting substituted (S)-1-phenyl ethanols are generated in very high enantiomeric excess.
- Vogl, Michael,Kratzer, Regina,Nidetzky, Bernd,Brecker, Lothar
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experimental part
p. 5863 - 5870
(2011/09/30)
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- Direct halogenation of organic compounds with halides using oxone in water - A green protocol
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Direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·KHSO4·K 2S04) in water was accomplished successfully in high-to-excellent yields. The main benefit of this protocol is the performance of the reactions in water in the presence of a harmless oxidant without the use of any organic cosolvents. Using NaBr and NaI as the safe sources of halogens is another advantage of the protocol. This method is easily applicable to the large-scale operations. We have also applied this method successfully for the iodocyclization of an unsaturated alcohol and an unsaturated carboxylic acid.
- Firouzabadi,Iranpoor,Kazemi
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experimental part
p. 1675 - 1681
(2010/01/29)
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- Magnesiated unsaturated silylated cyanohydrins as synthetic equivalents of aromatic and heterocyclic Grignard reagents bearing a ketone or an aldehyde
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The preparation of iodo-substituted aryl, heteroaryl, or cycloalkenyl ketones as silylated cyanohydrins allows the smooth performance of an l/Mg-exchange using i-PrMgCl·LiCl. A facile deprotection of the resulting functionalized products obtained by a rea
- Liu, Ching-Yuan,Ren, Hongjun,Knochel, Paul
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p. 617 - 619
(2007/10/03)
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- A short synthetic route to benzofurans. syntheses of naturally occurring euparin and related compounds
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Euparin (4a) and related benzofurans (4b-e, g) were synthesized by conversion of the corresponding o-(3-hydroxy-3-methylbutynyl)phenyl tosylates (2) in the presence of base into the 2-(1-hydroxy-1-methylethyl)benzofurans (3), followed by dehydration in hi
- Sogawa, Akihiro,Tsukayama, Masao,Nozaki, Hiroshi,Nakayama, Mitsuru
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p. 101 - 111
(2007/10/02)
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- Arocalciferols: Synthesis and biological evaluation of aromatic side-chain analogues of 1α,25-dihydroxyvitamin D31a
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Aromatic side-chain analogues (arocalciferols 6-9) of the steroid hormone 1α,25-dihydroxyvitamin D3 (1) were synthesized and biologically evaluated. The analogues were prepared by coupling the vitamin D A-ring enyne 14 with the appropriate enol
- Figadere,Norman,Henry,Koeffler,Zhou,Okamura
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p. 2452 - 2463
(2007/10/02)
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- Fragmentation of substituted acetophenone and halobenzophenone ketyls. Calibration of a mechanistic probe
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Disubstituted acetophenones, XC4H4COCH2Y, and benzophenoncs, XC4H4COC6H4Y, are used to measure the cleavage rate constants, kfY, of a series of α-substituted acetophenone ketyls and ring-substituted benzophenone ketyls. The cleavage rate constants can be determined from the competitive rates of fragmentation, kfY/kfX, of a series of ketyls, [XC6H4COCH2Y]- and [XC6H4COC6H4Y]-, since the rate constants, kfX, for a number of ketyl fragmentations have been electrochemically determined. Ring fragmentation is not significantly affected by substitution at the α-position of the acetophenone nor on the opposite ring of the benzophenone. The ketyls are formed by the reaction of 1,3-dimethyl-2-phenylbenzimidazoline (DMBI) with the disubstituted ketones. Ketyl fragmentation can be used as a diagnostic chemical probe for reactions of ketones suspected of having ketyl intermediates.
- Tanner, Dennis D.,Chen, Jian Jeffrey,Chen, Lucia,Luelo, Christine
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p. 8074 - 8081
(2007/10/02)
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- A Novel Aromatic Iodination Method Using F2
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A new method for direct aromatic iodination with IF, made in situ from the corresponding elements, is described.Depending on the reaction time and temperature, mono- or polyiodination can be achieved.Even deactivated aromatic rings can be directly iodinated without the presence of any Friedel-Crafts catalyst.Sensitive groups such as aromatic aldehydes are not affected by the reagent.
- Rozen, Shlomo,Zamir, Dov
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p. 3552 - 3555
(2007/10/02)
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- Reactions of Aryl Ketones and Coumarins with Iodine(III) Tris(trifluoroacetate)
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The reaction of acetophenones with iodine(III) tris(trifluoroacetate) yields 3'- and/or 2-iodo derivatives, depending upon the substituent on the aromatic ring and the reaction conditions.The reaction was examinedby changing the molar ratio of acetophenone versus the reagent, reaction temperature, and solvent.In similar reactions flavanones and coumarins gave iodo derivatives in which iodine is incorporated at various positions orientated by the oxygen functions. 1,2-Diphenylethanone yields 2-hydroxy-2-(2-iodophenyl)-1-phenylethanone and 1-(2-iodophenyl)-2-phenylethanedione.The reactions of other aromatic ketones such as 9-xanthenone, 9-fluorenone, and anthrone also give iodo derivatives in moderate to good yields.The mechanisms for the iodination at the α-carbon to the carbonyl group have been discussed.
- Fukuyama, Norihiro,Nishino, Hiroshi,Kurosawa, Kazu
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p. 4363 - 4368
(2007/10/02)
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