- Unusual carbonyl...carbonyl interaction in supramolecular structures of silver(I) complexes with 2,6-pyridinediylbis(4-pyridinyl)methanone
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A series of silver(I) complexes of a higher homologue of di-2-pyridyl ketone, 2,6-pyridinediylbis(4-pyridinyl)methanone (abbreviated as L), consisting of {[Ag(L)(BF4)]·H2O}∞ (1), {[Ag(L)(NO3)]·H2O}∞ (2), [Ag 3(L)2(NO2)3(H2O)] ∞ (3), [Ag(L)]2(PF6)2 (4), {[Ag(L)(CO2CF3)]2}∞ (5), [Ag(L)]2(SO3CF3)2 (6), and [Ag(L)]2(CO2CF2CF3)2 (7), have been synthesized and characterized. Complexes 1 and 2 are isomorphous helical polymers, 3 is a metallacycle featuring a trisilver(I) core, and 4-7 are isostructural complexes containing a common dinuclear [Ag2(L) 2]2+ metallacyclic skeleton. All complexes except 4 feature a common dominant intermolecular multipolar carbonyl...carbonyl interaction, which along with argentophilic Ag(I)...Ag(I), π...π, hydrogen-bonding, Ag...O=C, O(trifluoroacetate)...C= O as well as unconventional C=O...π and anion-π(pyridyl) interactions assemble the different coordination motifs (1-3, 5-7) into higher-dimensional frameworks. Three principal types of carbonyl...carbonyl interaction exhibiting antiparallel, sheared parallel, and perpendicular motifs are observed, and unusual supramolecular associations such as "...[C= O...C=O]n ..." (in 1-2 and 6) and "...[C= O...C=O...π]n..." (in 3) and "C=O...C=O...C=O" (in 7) are the novel structural features established in these complexes. The geometrical parameters and role of such noncovalent interactions in the construction of the present series of supramolecular metal-organic frameworks are discussed.
- Wan, Chong-Qing,Mak, Thomas C. W.
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Read Online
- Enhancing a Molecular Electrocatalyst's Activity for CO2Reduction by Simultaneously Modulating Three Substituent Effects
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The electrocatalytic activity for CO2 reduction is greatly enhanced for Co complexes with pyridyldiimine-based ligands through the stepwise integration of three synergistic substituent effects: extended conjugation, electron-withdrawing ability, and intramolecular electrostatic effects. The stepwise incorporation of these effects into the catalyst structures results in a series of complexes that show an atypical inverse scaling relationship for CO2 reduction - the maximum activity of the resulting catalysts increases as the onset potentials are driven positive due to the ligand electronic substituent effects. Incorporating all three effects simultaneously into the catalyst structure results in a Co complex [Co(PDI-PyCH3+I-)] with dramatically enhanced activity for CO2 reduction, operating with over an order of magnitude higher activity (TOFcat = 4.1 × 104 s-1) and ~0.2 V more positive catalytic onset (Eonset = -1.52 V vs Fc+/0) compared to the parent complex, an intrinsic activity parameter TOF0 = 6.3 × 10-3 s-1, and >95% Faradaic efficiency for CO production in acetonitrile with 11 M water. This makes [Co(PDI-PyCH3+I-)] among the most active molecular catalysts reported for the CO2 reduction reaction. Our work highlights a promising catalyst design strategy for molecular CO2RR catalysts in which catalytic ability is enhanced by tuning three synergistic substituent effects simultaneously in a single catalyst structure.
- Nie, Weixuan,Tarnopol, Drew E.,McCrory, Charles C. L.
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Read Online
- Electrophotochemical Ring-Opening Bromination oftert-Cycloalkanols
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An electrophotochemical ring-opening bromination of unstrainedtert-cycloalkanols has been developed. This electrophotochemical method enables the oxidative transformation of cycloalkanols with 5- to 7-membered rings into synthetically useful ω-bromoketones without the use of chemical oxidants or transition-metal catalysts. Alkoxy radical species would be key intermediates in the present transformation, which generate through homolysis of the O-Br bond in hypobromite intermediates under visible light irradiation.
- Yamamoto, Kosuke,Toguchi, Hiroyuki,Kuriyama, Masami,Watanabe, Shin,Iwasaki, Fumiaki,Onomura, Osamu
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p. 16177 - 16186
(2021/09/13)
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- Base-catalyzed aryl halide isomerization enables the 4-selective substitution of 3-bromopyridines
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The base-catalyzed isomerization of simple aryl halides is presented and utilized to achieve the 4-selective etherification, hydroxylation and amination of 3-bromopyridines. Mechanistic studies support isomerization of 3-bromopyridines to 4-bromopyridines proceedsviapyridyne intermediates and that 4-substitution selectivity is driven by a facile aromatic substitution reaction. Useful features of a tandem aryl halide isomerization/selective interception approach to aromatic functionalization are demonstrated. Example benefits include the use of readily available and stable 3-bromopyridines in place of less available and stable 4-halogenated congeners and the ability to converge mixtures of 3- and 5-bromopyridines to a single 4-substituted product.
- Bandar, Jeffrey S.,Puleo, Thomas R.
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p. 10517 - 10522
(2020/10/18)
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- Structure-activity relationship studies for the development of inhibitors of murine adipose triglyceride lipase (ATGL)
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High serum fatty acid (FA) levels are causally linked to the development of insulin resistance, which eventually progresses to type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) generalized in the term metabolic syndrome. Adipose triglyceride lipase (ATGL) is the initial enzyme in the hydrolysis of intracellular triacylglycerol (TG) stores, liberating fatty acids that are released from adipocytes into the circulation. Hence, ATGL-specific inhibitors have the potential to lower circulating FA concentrations, and counteract the development of insulin resistance and NAFLD. In this article, we report about structure–activity relationship (SAR) studies of small molecule inhibitors of murine ATGL which led to the development of Atglistatin. Atglistatin is a specific inhibitor of murine ATGL, which has proven useful for the validation of ATGL as a potential drug target.
- Breinbauer, Rolf,Doler, Carina,Fuchs, Elisabeth,Grabner, Gernot F.,Mayer, Nicole,Melcher, Michaela-Christina,Migglautsch, Anna K.,Romauch, Matthias,Schweiger, Martina,Zechner, Rudolf,Zimmermann, Robert
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supporting information
(2020/07/13)
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- One-pot homo- and cross-coupling of diazanaphthalenes via C-H substitution: Synthesis of Bis- and Tris-diazanaphthalenes
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The transition metal-free coupling reactions of unactivated diazanaphthalenes were studied using only lithium tetramethylpiperidine (LiTMP) reagent. Symmetrical and nonsymmetrical bis-diazanaphthalenes were synthesized in moderate to high yield by homo- and cross-coupling of related monomers. In addition, the single-step synthesis of diquinoxalino [2,3-a: 2', 3'c] phenazine and 2,2': 3', 2″ - terquinoxaline using the appropriate equivalent amount of LiTMP was performed. The products were characterized by means of NMR spectroscopy and HRMS spectrometry.
- Ucar, Sefa,Dastan, Arif
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supporting information
p. 4013 - 4022
(2020/09/21)
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- Size-Selective Hydroformylation by a Rhodium Catalyst Confined in a Supramolecular Cage
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Size-selective hydroformylation of terminal alkenes was attained upon embedding a rhodium bisphosphine complex in a supramolecular metal–organic cage that was formed by subcomponent self-assembly. The catalyst was bound in the cage by a ligand-template approach, in which pyridyl–zinc(II) porphyrin interactions led to high association constants (>105 m?1) for the binding of the ligands and the corresponding rhodium complex. DFT calculations confirm that the second coordination sphere forces the encapsulated active species to adopt the ee coordination geometry (i.e., both phosphine ligands in equatorial positions), in line with in situ high-pressure IR studies of the host–guest complex. The window aperture of the cage decreases slightly upon binding the catalyst. As a result, the diffusion of larger substrates into the cage is slower compared to that of smaller substrates. Consequently, the encapsulated rhodium catalyst displays substrate selectivity, converting smaller substrates faster to the corresponding aldehydes. This selectivity bears a resemblance to an effect observed in nature, where enzymes are able to discriminate between substrates based on shape and size by embedding the active site deep inside the hydrophobic pocket of a bulky protein structure.
- Nurttila, Sandra S.,Brenner, Wolfgang,Mosquera, Jesús,van Vliet, Kaj M.,Nitschke, Jonathan R.,Reek, Joost N. H.
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supporting information
p. 609 - 620
(2019/01/04)
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- Palladium-Catalysed Cross-Coupling Reactions Controlled by Noncovalent Zn???N Interactions
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Non-covalent interactions between halopyridine substrates and catalytically inert building blocks, namely zinc(II)–porphyrins and zinc(II)–salphens, influence the catalytic outcome of Suzuki–Miyaura and Mizoroki–Heck palladium-catalysed cross-coupling reactions. The weak Zn???N interactions between halopyridine substrates and zinc(II)-containing porphyrins and salphens, respectively, were studied by a combination of 1H NMR spectroscopy, UV/Vis studies, Job-Plot analysis and, in some cases, X-ray diffraction studies. Additionally, the former studies revealed unique supramolecular polymeric and dimeric rearrangements in the solid state featuring weak Br???N (halogen bonding), C?H???π, Br???π and π???π interactions. The reactivity of halopyridine substrates in homogeneous palladium-catalysed cross-coupling reactions was found to correlate with the binding strength between the zinc(II)-containing scaffolds and the corresponding halopyridine. Such observation is explained by the unfavourable formation of inactive over-coordinated halopyridine???palladium species. The presented approach is particularly appealing for those cases in which substrates and/or products deactivate (or partially poison) a transition-metal catalyst.
- Kadri, Mohamed,Hou, Jingran,Dorcet, Vincent,Roisnel, Thierry,Bechki, Lazhar,Miloudi, Abdellah,Bruneau, Christian,Gramage-Doria, Rafael
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supporting information
p. 5033 - 5043
(2017/04/18)
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- One-Pot, Metal-Free Conversion of Anilines to Aryl Bromides and Iodides
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A metal-free synthesis of aryl bromides and iodides from anilines via halogen abstraction from bromotrichloromethane and diiodomethane is described. This one-pot reaction affords aryl halides from the corresponding anilines in moderate to excellent yields without isolation of diazonium salts. The transformation has short reaction times, a simple workup, and insensitivity to moisture and air and avoids excess halogenation. DFT calculations support a SRN1 mechanism. This method represents a convenient alternative to the classic Sandmeyer reaction.
- Leas, Derek A.,Dong, Yuxiang,Vennerstrom, Jonathan L.,Stack, Douglas E.
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supporting information
p. 2518 - 2521
(2017/05/24)
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- Substituted Carbazoles-A New Class of Anthelmintic Agent
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A series of novel carbazoles were synthesized based on structural modifications to lead carbazole 1 (EC100≤2.5M against Haemonchus contortus in vitro), which was revealed in a small molecule screening program as a potentially promising platform for the development of new anthelmintic drugs. Subsequently, analogues 19, 21, 41, 42 (EC100≤ 1.25M, all), and 39 (EC100≤0.625M) were demonstrated to exhibit enhanced in vitro anthelmintic activity over the lead structure, with compound 39 also being shown to be active in vivo against Heligmosomoides polygyrus.
- Rennison, David,Gueret, Stephanie M.,Laita, Olivia,Bland, Ross J.,Sutherland, Ian A.,Boddy, Ian K.,Brimble, Margaret A.
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p. 1268 - 1276
(2016/11/25)
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- An activity-based fluorogenic probe for sensitive and selective monoamine oxidase-B detection
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We report the design and synthesis of a new class of fluorogenic probes based on monoamine oxidase-triggered oxidative C-O bond cleavage. The selectivity of probe P1 towards MAO-B was 22-fold higher than that towards MAO-A.
- Long, Shaobo,Chen, Lin,Xiang, Yumi,Song, Minggui,Zheng, Yuguo,Zhu, Qing
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supporting information; experimental part
p. 7164 - 7166
(2012/08/27)
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- New insights into the factors that govern the square/triangle equilibria of Pd(II) and Pt(II) supramolecules. Unexpected participation of a mononuclear species in the equilibrium
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The new rigid fluorinated ligand 4,4'-bis(4-pyridyl)octafluorobiphenyl (L1) has been synthesized by a nucleophilic substitution reaction between the organolithium derivative of the 4-bromopyridine and the compound decafluorobiphenyl. The use of L1 as building block of supramolecular species containing diphosphane or ethylenediamine Pd(II) and Pt(II) fragments has been explored, and the results have been compared with those previously reported for the smaller ligand 1,4-bis(4-pyridyl)tetrafluorobenzene (L2). The observed differences (particularly, square/triangle ratio) are discussed in terms of different parameters such as the nature of the ancillary ligands, solvent, or reaction temperature. The synthesis of water-soluble palladium metallamacrocycles derived from L1 has been attempted using ethylenediamine (en) or tetramethylethylenediamine (tmen) as ancillary ligand. Interestingly, in the latter case, the resulting solutions of the compounds showed, together with the square/triangle equilibrium, the unexpected presence of an additional lower nuclearity species, whose nature has been determined by means of bidimensional 1H NMR experiments.
- Ferrer, Montserrat,Pedrosa, Albert,Rodriguez, Laura,Rossell, Oriol,Vilaseca, Marta
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experimental part
p. 9438 - 9449
(2011/01/12)
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- Therapeutic Pyrazolyl Thienopyridines
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The present invention provides for compounds of Formula I, and pharmaceutically acceptable salts thereof, wherein R1, R2, R3, R4, R5, R6, and R7 have any of the values defined therefor in the specification, and pharmaceutically acceptable salts thereof, that are useful as therapeutic agents in the treatment of TGFβ-mediated conditions, including cancer and fibrotic disorders. Also provided are pharmaceutical compositions comprising one or more compounds of Formula I.
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Page/Page column 19
(2008/06/13)
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- SMALL ORGANIC MOLECULE REGULATORS OF CELL PROLIFERATION
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The present invention makes available methods and reagents for modulating proliferation or differentiation in a cell or tissue comprising contacting the cell with a compound. In certain embodiments, the methods and reagents may be employed to correct or inhibit an aberrant or unwanted growth state, e.g., by antagonizing a normal patched pathway or agonizing smoothened or hedgehog activity.
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Page/Page column 288-289
(2008/12/05)
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- Displacement of neutral nitrogen donors by chloride in AuCl3(am) (am = pyridines and amines): Kinetics and DFT calculations show the effects of basicity and π-acceptor ability
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The kinetics of the process AuCl3(am) + Cl- → AuCl4- + am (am = sp2 N-donor isosteric pyridines with different π systems and sp3 amines; they cover a wide range of basicity) have been studied in methanol at 25°C. The reactions obey the usual two-term rate law observed in substitutions on square-planar complexes. The second-order rate constants, k2, are very sensitive to the nature of the leaving group, and plots of log k2 against the pKa of the conjugate acids are linear, with the same slope, -0.68, for both normal pyridines and pyridines with a more extended π system, such as 4-cyanopyridine, isonicotinic acid, methyl isonicotinate and 4-acetylpyridine. The reactivity of the considered N-donors is different and follows the order sp3 N-donors > normal pyridines > π-extended pyridines. This result, with the support of ground-state DFT calculations on the AuCl3(am) derivatives, is explained on the basis of an Au-N bond enforcement due to an increased π-back-donation contribution. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Pitteri, Bruno,Bortoluzzi, Marco
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p. 4456 - 4461
(2008/03/12)
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- SUBSTITUTED ISOINDOLES AS BACE INHIBITORS AND THEIR USE
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This invention relates to novel compounds having the structural formula I and to their pharmaceutically acceptable salt, compositions and methods of use. These novel compounds provide a treatment or prophylaxis of cognitive impairment, Alzheimer Disease, neurodegeneration and dementia.
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Page/Page column 81-82
(2008/06/13)
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- NOVEL AZALIDE AND AZALACTAM DERIVATIVES AND PROCESS FOR THE PRODUCTION OF THE SAME
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A compound represented by the following general formula (1) or a pharmaceutically acceptable salt thereof, which is useful for a prophylactic and/or therapeutic treatment of a microbial infectious disease. [R1 is hydrogen atom, or a linear C1-6 alkylcarbonyl group; R2 is hydrogen atom, or a C1-6 alkylcarbonyl group; R3 is hydrogen atom, a C1-6 alkyl group, a C1-6 alkylcarbonyl group, a C1-6 alkenyl group, a C2-6 alkenylcarbonyl group, a C2-6 alkynyl group, or an Ar-B- group (Ar represents an aryl group, or a heterocyclic group, and B is a C1-6 alkyl group, a C1-6 alkylcarbonyl group, a C2-6 alkenyl group, a C2-6 alkenylcarbonyl group, or a C2-6 alkynyl group); R5, R6, R7, and R8 represent hydrogen atom, a C1-6 alkyl group, a C2-6 alkenyl group, a C2-6 alkynyl group, or an Ar-B'- group (B' is a C1-6 alkyl group, a C2-6 alkenyl group, or a C2-6 alkynyl group); X is oxygen atom, or an -NR4- group (R4 is hydrogen atom, a C1-6 alkyl group, or a C1-6 alkyl group which may be substituted with an Ar group); and R4' is hydrogen atom, or a group represented by the aforementioned formula (a) (R3" and R4" represent hydrogen atom, or a linear or branched C1-6 alkylcarbonyl group)]
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Page/Page column 44
(2010/11/08)
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- INSECTICIDAL TRICYCLIC DERIVATIVES
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It has now been found that certain tricyclic derivatives have provided unexpected insecticidal activity. These compounds are represented by formula I: wherein R through R, inclusively, and X and Y are fully described. Compositions comprising an insecticidally effective amount of at least one compound of formula I, and optionally, an effective amount of at least one of a second compound, with at least one insecticidally compatible carrier are also disclosed; along with methods of controlling insects comprising applying said compositions to the locus where insects are present or are expected to be present.
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- PIPERAZINE DERIVATIVES AS 5-HT1B ANTAGONISTS
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Piperazine derivatives of formula(1),processes for their preparation, pharmaceutical compositions containing them in the treatment of CNS and other disorders and in their use in therapy as 5-HT1B antagonists are disclosed herein.
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- Indoles
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A 1,4-substituted cyclic amine derivative represented by the following formula or a pharmacologically acceptable salt thereof: wherein A, B, C, D, T, Y, and Z each represent a methine or a nitrogen linkage; R1, R2, R3, R4, and R5 each represent a substituent; n represents 0 or an integer of 1 to 3; m represents 0 or an integer of 1 to 6; and p represents an integer of 1 to 3. The compounds have serotonin antagonism. They are therefore clinically useful as medicaments, in particular, for treating, ameliorating, and preventing spastic paralysis. They are also useful as central muscle relaxants for ameliorating myotonia.
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- Substituted isoindolones and their use as cyclic GMP modulators in medicaments
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The present invention relates to substituted isoindolone derivatives of the formula I, in which R1, R2, R3, R4, R5, R6and R7are as defined in the claims, which are useful pharmaceutically active compounds for the therapy and prophylaxis of illnesses, for example cardiovascular diseases such as hypertension, angina pectoris, cardiac insufficiency, thromboses or atherosclerosis. The compounds of the formula I are capable of modulating the body's production of cyclic guanosine monophosphate (cGMP) and are generally suitable for the therapy and prophylaxis of illnesses which are associated with a disturbed cGMP balance. The invention furthermore relates to processes for preparing compounds of the formula I, to their use for the therapy and prophylaxis of the abovementioned illnesses and for preparing pharmaceuticals for these, and also pharmaceutical preparations which comprise compounds of the formula I.
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Page column 14
(2010/01/30)
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- à-aminoacetic acid derivatives-à4β7 receptor antagonists
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Disclosed are compounds which bind à4β7 integrin. Certain of these compounds also inhibit leukocyte adhesion and, in particular, leukocyte adhesion mediated by à4β7 integrin. Such compounds are useful in the treatment of inflammatory diseases in a mammalian patient, e.g., human, such as asthma, Alzheimer's disease, atherosclerosis, AIDS dementia, diabetes, inflammatory bowel disease, rheumatoid arthritis, tissue transplantation, tumor metastasis and myocardial ischemia. The compounds can also be administered for the treatment of inflammatory brain diseases such as multiple sclerosis.
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Page column 43
(2010/02/05)
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- NOVEL SULFONYL DERIVATIVES
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Sulfonyl derivatives represented by the following general formula (I): Q1-Q2-T1-Q3-SO2-QA and drugs containing the same (wherein Q1 is an optionally substituted, saturated or unsaturated, five- or six-membered cyclic hydrocarbon group, a five- or six-membered heterocyclic group, or the like; Q2 is a single band, oxygen, sulfur, C1-C6 alkylene or the like; QA is optionally substituted arylalkenyl, heteroarylalkenyl or the like; and T1 is carbonyl or the like). These compounds have potent FXa-inhibitory effects and promptly exert satisfactory and persistent antithrombotic effects through oral administration, thus being useful as anticoagulant agents little accompanied with side effects.
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- Indium-mediated deoxygenation of nitrones, N-oxides and deoxygenative reductive coupling of nitrones to vicinal diamines
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We reported transformation of nitrones selectively either to aldamines or vicinal diamines and deoxygenation of N-oxides using Indium at ambient temperature in good yields.
- Jeevanandam, Arumugasamy,Cartwright, Charles,Ling, Yong-Chien
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p. 3153 - 3160
(2007/10/03)
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- Metalloproteinase inhibitors, pharmaceutical compositions containing them, and their use
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The present invention is directed to compound of the formula I: STR1 wherein R1, R2, R3, R4, R5, X, Y, and STR2 are as defined herein. These compounds are useful for inhibiting the activity of a metalloproteinase by contacting the metalloproteinase with an effective amount of the inventive compounds.
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- Substituted heterocyclylisoquinolinium salts and compositions and method of use thereof
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Substitutued heterocyclylisoquinolinium salts, pharmaceutical compositions containing them and methods for the treatment or prevention of neurodegenerative disorders or neurotoxic injuries utilizing them.
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- Substituted 6,11-ethano-6,11-dihydrobenzo[b] quinolizinium salts and compositions and methods of use thereof
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Substituted 6,11-ethano-6,11-dihydrobenzo[b]quinolizinium salts, pharmaceutical compositions containing them, and methods for the treatment of neurodegenerative disorders or neurotoxic injuries utilizing them, wherein the substituted 6,11-ethano-6,11-dihydrobenzo[b]quinolizinium salts have the formula: STR1 wherein: R1, R2, R3, R4, R5, R6, R7, X and p are as defined in the specification.
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- Preparation of Didehydropyridines from (Trimethylsilyl)pyridines
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Halogen-substituted (trimethylsilyl)pyridines 2, 3, 5-7 and trifluoromethylsulfonyloxy-substituted (trimethylsilyl)pyridines 9b, 11b are obtained from 2- and 3-halopyridines 1, 4 or hydroxypyridines 8, 10, and 12.Reactions of the 3- and 2-(trimethylsilyl)pyridines 2, 9b and 11b with bases in the presence of furans 15 give only protodesilylation or hydrolysis products but no indication is found for the formation of a 2,3-didehydropyridine. 3-Bromo-4-(trimethylsilyl)pyridine (5a) reacts with KOCMe3 in the presence of furan (15a) to give a mixture of products from which the isoquinoline derivative 20 and the tert-butoxypyridines 23, 24 are formed by addition to 3,4-didehydropyridine.Under comparable conditions far higher yields of 3,4-didehydropyridines are obtained by treatment of the 3-halo-2,4-bis(trimethylsilyl)pyridines 7 with strong bases. Key Words: Didehydropyridines, synthesis of
- Effenberger, Franz,Daub, Wolfgang
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p. 2119 - 2125
(2007/10/02)
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- Titanium(0) Reagents; 2. A Selective and Efficient Deoxygenation of Halogen Containing Heteroaromatic N-Oxides
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Following successful reductions of unfunctionalized heteroaromatic N-oxides by titanium(0), we applied this method to halogenated aromatic N-oxides to give the deoxygenated halogeno derivatives in 90-95percent yield.
- Malinowski, Marek,Kaczmarek, Lukasz
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p. 1013 - 1015
(2007/10/02)
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- HOMOTRANSMETALLATION DES HALOGENO-3 PYRIDINES BROMEES EN -2 OU -4 PAR LE N-BUTYLLITHIUM. PROPOSITION D'UN NOUVEAU MECANISME DE TELESUBSTITUTION DU BROME.
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These are new examples of the homotransmetallation reaction.Instead of the ordinary bromo-metal exchange it is possible to obtain selectively from the 2-bromo 3-fluoro or 2-bromo 3-chloro pyridines the 2-bromo 3-halogeno 4-lithio pyridines, which is very interesting for synthetic utility.From the 4-bromo 3-halogeno pyridines, we can see an isomerization with an halogen dance mechanism and we obtain the 5-bromo 3-halogeno 4-lithio pyridines.In the case of the 2-bromo 3-fluoro pyridine we explain a telesubstitution of bromine from 2 to 4 by a transitory homotransmetallation reaction during the Li-Br exchange.
- Mallet, M.,Queguiner, G.
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p. 2253 - 2262
(2007/10/02)
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- REACTION DE LA BROMO-3 PYRIDINE AVEC LE DIISOPROPYLAMIDURE DE LITHIUM. MECANISMES DE METALLATION ET DE MIGRATION D'HALOGENE. REGIOSELECTIVITE DE L'ADDITION POLAIRE SUR LA PYRIDYNE-3,4
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3-bromo pyridine behaviour towards lithium diisopropyl amide (LDA) in THF is studied.A careful study of the experimental conditions point to a metallation reaction in a position 4 and a "halogen dance" mechanism with isomerisation into a 4-bromo pyridine.Conversion into diisopropylamino compounds occurs simultaneously with a 3 oriented elimination-addition (EA) reaction from transient isomeric lithio-derivatives and a competing addition-elimination (AE) mechanism from the in situ formed 4-bromo pyridine.
- Mallet, M.,Queguiner, G.
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p. 3035 - 3042
(2007/10/02)
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