- Dirhodium-Catalyzed Enantioselective B?H Bond Insertion of gem-Diaryl Carbenes: Efficient Access to gem-Diarylmethine Boranes
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The scarcity of reliable methods for synthesizing chiral gem-diarylmethine borons limits their applications. Herein, we report a method for highly enantioselective dirhodium-catalyzed B?H bond insertion reactions with diaryl diazomethanes as carbene precursors. These reactions afforded chiral gem-diarylmethine borane compounds in high yield (up to 99 % yield), high activity (turnover numbers up to 14 300), high enantioselectivity (up to 99 % ee) and showed unprecedented broad functional group tolerance. The borane compounds synthesized by this method could be efficiently transformed into diaryl methanol, diaryl methyl amine, and triaryl methane derivatives with good stereospecificity. Mechanistic studies suggested that the borane adduct coordinated to the rhodium catalyst and thus interfered with decomposition of the diazomethane, and that insertion of a rhodium carbene (generated from the diaryl diazomethane) into the B?H bond was most likely the rate-determining step.
- Huang, Ming-Yao,Li, Xiao-Yu,Su, Yu-Xuan,Yang, Liang-Liang,Zhao, Yu-Tao,Zhu, Shou-Fei
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supporting information
p. 24214 - 24219
(2021/10/07)
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- Novel and efficient bridged bis(N-heterocyclic carbene)palladium(II) catalysts for selective carbonylative Suzuki–Miyaura coupling reactions to biaryl ketones and biaryl diketones
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Bridged N,N′-substituted bisbenzimidazolium bromide salts (L1, L2, and L3) were synthesized and fully characterized. Reactions of palladium acetate with L1, L2, and L3 afforded corresponding new bridged bis(N-heterocyclic carbene)palladium(II) complexes (C1, C2, and C3) in high yields. The X-ray structure of complex C1 showed that the Pd(II) ion is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromido ligands are in the cis position, resulting in a distorted square planar geometry. The three Pd(NHC)2Br2 complexes C1, C2, and C3 were evaluated in carbonylative Suzuki–Miyaura coupling reactions of aryl boronic acids with aryl halides and displayed high catalytic activity with low catalyst loading. The coupling reactions of aryl bromides were selective towards the carbonylation product at higher carbon monoxide pressure.
- El Ali, Bassam,Fettouhi, Mohammed,Mansour, Waseem
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- Base-free nickel-catalysed decarbonylative Suzuki–Miyaura coupling of acid fluorides
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The Suzuki–Miyaura cross-coupling of organoboron nucleophiles with aryl halide electrophiles is one of the most widely used carbon–carbon bond-forming reactions in organic and medicinal chemistry1,2. A key challenge associated with these transformations is that they generally require the addition of an exogenous base, the role of which is to enable transmetallation between the organoboron nucleophile and the metal catalyst3. This requirement limits the substrate scope of the reaction because the added base promotes competitive decomposition of many organoboron substrates3–5. As such, considerable research has focused on strategies for mitigating base-mediated side reactions6–12. Previous efforts have primarily focused either on designing strategically masked organoboron reagents (to slow base-mediated decomposition)6–8 or on developing highly active palladium precatalysts (to accelerate cross-coupling relative to base-mediated decomposition pathways)10–12. An attractive alternative approach involves identifying combinations of catalyst and electrophile that enable Suzuki–Miyaura-type reactions to proceed without an exogenous base12–14. Here we use this approach to develop a nickel-catalysed coupling of aryl boronic acids with acid fluorides15–17, which are formed in situ from readily available carboxylic acids18–22. This combination of catalyst and electrophile enables a mechanistic manifold in which a ‘transmetallation-active’ aryl nickel fluoride intermediate is generated directly in the catalytic cycle13,16. As such, this transformation does not require an exogenous base and is applicable to a wide range of base-sensitive boronic acids and biologically active carboxylic acids.
- Malapit, Christian A.,Bour, James R.,Brigham, Conor E.,Sanford, Melanie S.
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p. 100 - 104
(2018/11/25)
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- Rapidly Activating Pd-Precatalyst for Suzuki-Miyaura and Buchwald-Hartwig Couplings of Aryl Esters
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Esters are valuable electrophiles for cross-coupling due to their ubiquity and ease of synthesis. However, harsh conditions are traditionally required for the effective cross-coupling of ester substrates. Utilizing a recently discovered precatalyst, Pd-catalyzed Suzuki-Miyaura and Buchwald-Hartwig reactions involving cleavage of the C(acyl)-O bond of aryl esters that proceed under mild conditions are reported. The Pd(II) precatalyst is highly active because it is reduced to the Pd(0) active species more rapidly than previous precatalysts.
- Dardir, Amira H.,Melvin, Patrick R.,Davis, Ryan. M.,Hazari, Nilay,Mohadjer Beromi, Megan
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supporting information
p. 469 - 477
(2018/02/19)
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- Ni-Catalyzed cross-coupling reactions of N-acylpyrrole-type amides with organoboron reagents
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The catalytic conversion of amides to ketones is highly desirable yet challenging in organic synthesis. We herein report the first Ni/bis-NHC-catalyzed cross-coupling of N-acylpyrrole-type amides with arylboronic esters to obtain diarylketones. This method is facilitated by a new chelating bis-NHC ligand. The reaction tolerates diverse functional groups on both arylamide and arylboronic ester partners including sensitive ester and ketone groups.
- Huang, Pei-Qiang,Chen, Hang
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p. 12584 - 12587
(2017/11/30)
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- Palladium-catalyzed Suzuki-Miyaura coupling of amides by carbon-nitrogen cleavage: General strategy for amide N-C bond activation
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The first palladium-catalyzed Suzuki-Miyaura cross-coupling of amides with boronic acids for the synthesis of ketones by sterically-controlled N-C bond activation is reported. The transformation is characterized by operational simplicity using bench-stable, commercial reagents and catalysts, and a broad substrate scope, including substrates with electron-donating and withdrawing groups on both coupling partners, steric-hindrance, heterocycles, halides, esters and ketones. The scope and limitations are presented in the synthesis of >60 functionalized ketones. Mechanistic studies provide insight into the catalytic cycle of the cross-coupling, including the first experimental evidence for Pd insertion into the amide N-C bond. The synthetic utility is showcased by a gram-scale cross-coupling and cross-coupling at room temperature. Most importantly, this process provides a blueprint for the development of a plethora of metal catalyzed reactions of typically inert amide bonds via acyl-metal intermediates. A unified strategy for amide bond activation to enable metal insertion into N-C amide bond is outlined (Scheme 1).
- Meng, Guangrong,Szostak, Michal
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supporting information
p. 5690 - 5707
(2016/07/06)
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- Nickel-Catalyzed Decarbonylative Coupling of Aryl Esters and Arylboronic Acids
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A variety of functionalized biaryls can be accessed by coupling aryl and heteroaryl esters with boronic acids in Suzuki-Miyaura-type decarbonylative cross-coupling catalyzed by an affordable catalyst system composed of Ni(cod)2 and PCy3. The methodology is tolerant of a variety of functional groups and presents an attractive alternative to the use of palladium catalysis currently used in industry to acquire such bis(hetero)aryls, but also reveals challenges associated with nickel catalysis of esters in cross-coupling chemistry.
- Laberge, Nicole A.,Love, Jennifer A.
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supporting information
p. 5546 - 5553
(2015/09/01)
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- Development of a benzophenone and alkyne functionalised trehalose probe to study trehalose dimycolate binding proteins
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Trehalose dimycolates (TDMs) are the most abundant glycolipids found in the cell wall of Mycobacterium tuberculosis (M. tb). TDMs play an important role in the pathogenesis of M. tb yet the only known receptor for TDM is the macrophage inducible C-type lectin (mincle). To understand more about the interaction of TDMs with immune cells, affinity based proteome profiling (AfBPP) can be used to determine receptors that bind TDMs. To this end, we present the synthesis of the first AfBPP-TDM probe and report on its ability to activate macrophages. By doing so, we establish that the AfBPP-TDM probe appears to be a suitable substrate for future proteomic profiling experiments.
- Khan, Ashna A.,Kamena, Faustin,Timmer, Mattie S.M.,Stocker, Bridget L.
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supporting information
p. 881 - 885
(2013/02/26)
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- Chemoselective synthesis of ketones and ketimines by addition of organometallic reagents to secondary amides
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The development of efficient and selective transformations is crucial in synthetic chemistry as it opens new possibilities in the total synthesis of complex molecules. Applying such reactions to the synthesis of ketones is of great importance, as this motif serves as a synthetic handle for the elaboration of numerous organic functionalities. In this context, we report a general and chemoselective method based on an activation/addition sequence on secondary amides allowing the controlled isolation of structurally diverse ketones and ketimines. The generation of a highly electrophilic imidoyl triflate intermediate was found to be pivotal in the observed exceptional functional group tolerance, allowing the facile addition of readily available Grignard and diorganozinc reagents to amides, and avoiding commonly observed over-addition or reduction side reactions. The methodology has been applied to the formal synthesis of analogues of the antineoplastic agent Bexarotene and to the rapid and efficient synthesis of unsymmetrical diketones in a one-pot procedure. Macmillan Publishers Limited. All rights reserved.
- Bechara, William S.,Pelletier, Guillaume,Charette, Andre B.
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experimental part
p. 228 - 234
(2012/06/01)
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- "Greener" Friedel-Crafts acylations: A metal- and halogen-free methodology
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Chemical equations presented. The utility of methanesulfonic anhydride for promoting the Friedel-Crafts acylation reaction of aryl and alkyl carboxylic acids is disclosed. This reagent allows the preparation of aryl ketones in good yield with minimal waste containing no metallic or halogenated components, clearly differentiating it from other available methodologies.
- Wilkinson, Mark C.
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supporting information; experimental part
p. 2232 - 2235
(2011/06/24)
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- Synthesis of trifunctional phosphatidylserine probes for identification of lipid-binding proteins
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Phosphatidylserine (PS) lipids play a number of roles in cell biology, one of which is to mark apoptotic cells for clearance by macrophages. PS recognition triggers macrophage recognition and clearance, which occurs concomitantly with active suppression o
- Bandyopadhyay, Saibal,Bong, Dennis
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supporting information; experimental part
p. 751 - 758
(2011/03/22)
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- Novel 5α-reductase inhibitors: Synthesis, structure-activity studies, and pharmacokinetic profile of phenoxybenzoylphenyl acetic acids
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Novel substituted benzoyl benzoic acids and phenylacetic acids 1-14 have been synthesized and evaluated for inhibition of rat and human steroid 5α-reductase isozymes 1 and 2, The compounds turned out to be potent and selective human type 2 enzyme inhibitors, exhibiting IC50 values in the nanomolar range. The phenylacetic acid derivatives were more potent than the analogous benzoic acids. Bromination in the 4-position of the phenoxy moiety led to the strongest inhibitor in this class (12; IC50 = 5 nM), which was equipotent to finasteride. Since oral absorption is essential for a potential drug, 12 was further examined. In the parallel artificial membrane permeation assay (PAMPA) it turned out to be a good permeator, whereas it was a medium permeator in Caco2 cells. After oral administration (40 mg/kg) to rats a high bioavailability and a biological half-life of 5.5 h were observed, making it a promising candidate for clinical evaluation.
- Salem, Ola I. A.,Frotscher, Martin,Scherer, Christiane,Neugebauer, Alexander,Biemel, Klaus,Streiber, Martina,Maas, Ruth,Hartmann, Rolf W.
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p. 748 - 759
(2007/10/03)
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- CHEMICAL COMPOUNDS
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The present invention relates to novel compounds with a variety of therapeutic uses, more particularly novel substituted cyclic alkylidene compounds that are particularly useful for selective estrogen receptor modulation.
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Page/Page column 54
(2008/06/13)
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- GLUCAGON RECEPTOR ANTAGONISTS, PREPARATION AND THERAPEUTIC USES
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The present invention discloses novel compounds of Formula (I), or pharmaceutically acceptable salts thereof, which have glucagon receptor antagonist or inverse agonist activity, as well as methods for preparing such compounds. In another embodiment, the invention discloses pharmaceutical compositions comprising compounds of Formula (I) as well as methods of using them to treat diabetic and other glucagon related metabolic disorders, and the like.
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Page/Page column 145-146
(2010/02/15)
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- High-Throughput Synthesis of Alkylbenzophenones with Indium Triflate in the Absence of Solvents Using Microwave
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A series of alkylbenzophenones were rapidly and efficiently prepared from alkylbenzenes and benzoyl chlorides by Friedel-Crafts acylation catalyzed with indium triflate under solvent-free conditions by microwave heating.
- Koshima, Hideko,Kubota, Masashi
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p. 3983 - 3988
(2007/10/03)
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- BENZAMIDINE DERIVATIVES
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Benzamidine derivatives of the following formulae or analogs thereof, i. e., pharmaceutically acceptable salts thereof, are provided. These compounds or salts thereof have a blood-coagulation inhibiting effect based on an excellent effect of inhibiting the action of activated blood coagulation factor X, and they are useful as anticoagulants.
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- CONDENSED PYRAZOLE DERIVATIVES, METHOD OF MANUFACTURING THE SAME, AND ANDROGEN INHIBITOR
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This invention provides a condensed pyrazole derivative of the Formula (1): STR1 (where A denotes CH or N, R 0 and R 3 denote same or different, a hydrogen atom or a lower alkyl group, R 1 and R 2 denote same or different, a hydrogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group, a nitro group or a halogen atom, m denotes 1 or 2, and n denotes 1, 2 or 3, provided that, when n is 2, two R 2 may be connected to each other to form a lower alkylenedioxy group), or its pharmaceutically acceptable salt. This derivative or its salt is excellent in the effect of inhibiting the expression of action of androgen, thereby being excellent in therapeutical effect of benign prostatic hypertrophy, prostatic carcinoma, etc., and has a long lasting of efficacy and high oral absorption.
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