- Decarboxylative Bromination of Sterically Hindered Carboxylic Acids with Hypervalent Iodine(III) Reagents
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Sterically hindered three-dimensional (3D) alkyl halides are promising precursors for various reactions; however, they are difficult to synthesize via conventional reactions. We present an efficient and practical method for decarboxylative bromination of sterically hindered 3D aliphatic carboxylic acids using commercially available (diacetoxyiodo)benzene and potassium bromide, one of the most stable and cheapest bromine sources in nature. The present method features a metal-free/Br2-free system, mild reaction conditions, one-pot operation under air at room temperature, wide functional group compatibility, and gram-scale synthetic capability. This highly efficient reaction cleanly converts a broad range of carboxylic acids, the most inexpensive and readily available sources of highly strained/naturally occurring/drug-related scaffolds, into the corresponding alkyl bromides in good to high yields.
- Kanazawa, Junichiro,Koyamada, Kenta,Miyamoto, Kazunori,Uchiyama, Masanobu,Watanabe, Ayumi
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supporting information
p. 1328 - 1334
(2020/08/14)
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- PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
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The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
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Paragraph 00169; 00180; 00183
(2017/07/28)
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- MANUFACTURING METHOD OF BROMINATED CYCLOPROPANES
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PROBLEM TO BE SOLVED: To provide a manufacturing method capable of simply providing bromoalkyl cyclopropanes in an industrial scale. SOLUTION: There is provided a manufacturing method of bromoalkyl cyclopropanes represented by the formula (3) or the formula (4) by reacting corresponding alcohols and HBr dissolved in an aprotic solvent such as 1,4-dioxanes and substituting a hydroxyl group by Br. (3) (4), where R1 is H, a C1 to 10 substituted/unsubstituted linear/branched alkyl group, a C3 to 10 substituted/unsubstituted cyclic alkyl group, R2 is a substituted/unsubstituted phenyl group and n is an integer of 1 to 10. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0033
(2017/04/28)
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- Structural and Electronic Noninnocence of α-Diimine Ligands on Niobium for Reductive C-Cl Bond Activation and Catalytic Radical Addition Reactions
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A d0 niobium(V) complex, NbCl3(α-diimine) (1a), supported by a dianionic redox-active N,N′-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadiene (α-diimine) ligand (ene-diamido ligand) served as a catalyst for radical addition reactions of CCl4 to α-olefins and cyclic alkenes, selectively affording 1:1 radical addition products in a regioselective manner. During the catalytic reaction, the α-diimine ligand smoothly released and stored an electron to control the oxidation state of the niobium center by changing between an η4-(σ2,π) coordination mode with a folded MN2C2 metallacycle and a κ2-(N,N′) coordination mode with a planar MN2C2 metallacycle. Kinetic studies of the catalytic reaction elucidated the reaction order in the catalytic cycle: the radical addition reaction rate obeyed first-order kinetics that were dependent on the concentrations of the catalyst, styrene, and CCl4, while a saturation effect was observed at a high CCl4 concentration. In the presence of excess amounts of styrene, styrene coordinated in an η2-olefinic manner to the niobium center to decrease the reaction rate. No observation of oligomers or polymers of styrene and high stereoselectivity for the radical addition reaction of CCl4 to cyclopentene suggested that the C-C bond formation proceeded inside the coordination sphere of niobium, which was in good accordance with the negative entropy value of the radical addition reaction. Furthermore, reaction of 1a with (bromomethyl)cyclopropane confirmed that both the C-Br bond activation and formation proceeded on the α-diimine-coordinated niobium center during transformation of the cyclopropylmethyl radical to a homoallyl radical. With regard to the reaction mechanism, we detected and isolated NbCl4(α-diimine) (6a) as a transient one-electron oxidized species of 1a during reductive cleavage of the C-X bonds; in addition, the monoanionic α-diimine ligand of 6a adopted a monoanionic canonical form with selective one-electron oxidation of the dianionic ene-diamido form of the ligand in 1a.
- Nishiyama, Haruka,Ikeda, Hideaki,Saito, Teruhiko,Kriegel, Benjamin,Tsurugi, Hayato,Arnold, John,Mashima, Kazushi
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p. 6494 - 6505
(2017/09/12)
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- Production of ethylcycloalkanes bromomethylbiphenyl
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PROBLEM TO BE SOLVED: To provide a production method by which bromomethyl cycloalkanes can be easily obtained in an industrial scale.SOLUTION: A method for producing bromomethyl cycloalkanes comprises brominating cycloalkyl methanols by use of hydrogen bromide, wherein the reaction is carried out in the presence of an ionic liquid.
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Paragraph 0036-0038; 0042-0052
(2018/10/16)
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- Carbonic anhydrase inhibitors. Regioselective synthesis of novel series 1-substituted 1,4-dihydro-4-oxo-3-pyridinesulfonamides and their inhibition of the human cytosolic isozymes i and II and transmembrane cancer-associated isozymes IX and XII
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A series of novel 1-substituted 1,4-dihydro-4-oxo-3-pyridinesulfonamides 4-6, 9-17 and 21-31 have been synthesized and investigated as inhibitors of four isoforms of zinc enzyme carbonic anhydrase (CA.EC 4.2.1.1), that is the cytosolic CA I and II, and cancer-associated isozymes CA IX and XII. Against the human isozymes hCA I the new compounds showed KIs in the range of 224-4830 nM, whereas toward hCA II, KIs = 318-873 nM. Isozyme hCA IX was inhibited with KIs = 11.8-93.4 nM, and hCA XII with 23.5-82.3 nM. Compounds 12-14, 27 and 29-31 have an activity against hCA I (KIs = 224-889 nM) which is comparable to the clinically used sulfonamide DCP (K Is = 1200 nM). Several of new compounds, including 9, 10, 21, 24, 26-28 and 30 have an activity against hCA IX (KIs = 11.8-38.6 nM) which is comparable or more effective than the clinically used sulfonamides AAZ, MZA, EZA, DCP and IND (KIs = 24-50 nM). Compounds 9, 10, 13, 21-23, 26 and 27 were also very effective hCA XII inhibitors, with inhibition constants ranged from 23.5 to 47.2 nM comparable or more effective than sulfonamides EZA (KIs = 22 nM) or DCP (KIs = 50 nM), respectively.
- Brzozowski, Zdzislaw,Slawinski, Jaroslaw,Vullo, Daniela,Supuran, Claudiu T.
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p. 282 - 291,10
(2012/12/11)
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- Rearrangement, nucleophilic substitution, and halogen switch reactions of alkyl halides over NaY zeolite: Formation of the bicyclobutonium cation inside the zeolite cavity
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Rearrangement and nucleophilic substitution of cyclopropylcarbinyl bromide over NaY and NaY impregnated with NaCl was observed at room temperature. The first-order kinetics are consistent with ionization to the bicyclobutonium cation, followed by internal return of the bromide anion or nucleophilic attack by impregnated NaCl to form cyclopropylcarbinyl, cyclobutyl, and allylcarbinyl chlorides. The product distribution analysis revealed that neither a purely kinetic distribution, similar to what is found in solution, nor the thermodynamic ratio, which favors the allylcarbinyl halide, was observed. Calculations showed that bicyclobutonium and cyclopropylcarbinyl carbocations are minimal over the zeolite structure, and stabilized by hydrogen bonding with the framework structure. A new process of nucleophilic substitution is reported, namely halogen switch, involving alkyl chlorides and bromides of different structures. The reaction occurs inside the zeolite pores, due to the confinement effects and is an additional proof of carbocation formation on zeolites. The results support the idea that zeolites act as solid solvents, permitting ionization and solvation of ionic species.
- Franco, Marcelo,Rosenbach Jr., Nilton,Ferreira, Glaucio B.,Guerra, Antonio C. O.,Kover, W. Bruce,Turci, Cassia C.,Mota, Claudio J. A.
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p. 1592 - 1600
(2008/09/18)
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- Esterification of carboxylic acid salts
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Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
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- A Convenient Large-Scale Synthesis of Cyclobutyl Halides
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An improved method for the preparation of multigram quantities of cyclobutyl halides is described.The Grignard reactivity of these halides is also discussed.
- Dupont, Andrea C.,Audia, Vicki H.,Waid, Philip P.,Carter, J. Paul
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p. 1011 - 1021
(2007/10/02)
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- Surface Reactions, 9 / Dehydrohalogenation of Halohydrocarbons at Raney Nickel
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Raney nickel, a highly reactive and air-sensitive solid, if prepared and investigated under oxygen-free conditions, exhibits interesting catalytic properties.Using photoelectron spectroscopy for real-time gas analysis in a flow reactor, the following results are obtained with alkyl and acylhalides: Dehydrohalogenation temperatures are lowered relative to thermal HHal elimination up to 350 K.Monochloro and bromo propanes and butenes yield propene and butadiene, respectively. 1,1-Dichloro ethane or 1,1-dibromo propane only split off one HHal and form chloroethene or 1,1-bromopropene-2.HCl elimination from 2-methyl propionic acid chloride, expectedly, produces dimethyl ketene.Most interesting, however, is the ring opening of monobromo cyclobutane to 1-bromo-butene-3, observed already at room temperature, which strongly suggests the intermediate formation of a chemisorbed surface carbene at Raney nickel.The formation of hexadiene-1,5 as a by-product in the HCl elimination of 1-chloropropane, i.e. a surface carbene dimer, indicates their presence also in other dehydrohalogenations heterogeneously catalyzed by Raney nickel.
- Bock, Hans,Wolf, Hans Peter
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p. 699 - 714
(2007/10/02)
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- ANALYSE STRUCTURALE EN SERIE CYCLOBUTANIQUE. Partie 1. Derives monosubstitues et gem disubstitues du cyclobutane
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Methylene bending mode analysis of some cyclobutane-d2 molecules reveals that in the dissolved state (solvent CCl4), bromocyclobutane occurs exclusively in a pseudo-equatorial form, whereas, under the same conditions, cyclobutanol and 1-bromocyclobutane carbonitrile exist both in pseudo-axial and pseudo-equatorial conformations.NMR spectroscopy confirms the results obtained for bromocyclobutane and leads to the conclusion that the pseudo-equatorial conformer is predominant in the case of cyclobutanol as well as in that of cyclobutane carbonitrile.A theoretical study of cyclobutanol in the gaseous state by the P.C.I.L.O. method gives results which are consistent with a pseudo-equatorial conformer.
- Karimine, Mohamed,Galsomias, Jacqueline,Lere-Porte, Jean-Pierre,Petrissans, Jean
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p. 321 - 332
(2007/10/02)
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- 1,2-DIMETHYLSPIROHEX-1-ENE BY ADDITION OF CYCLOBUTYLIDENE TO 2-BUTYNE
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The first addition of a cyclobutylidene (carbenoid) to an alkyne is reported.By C4+C2-coupling the spirohex-1-ene system 8 is constructed.Furthermore, cyclobutylidene adds to methylenecyclopropane, its intramolecular reaction product, to give the novel dispirooctane 11.
- Brinker, Udo H.,Weber, Juergen
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p. 5371 - 5374
(2007/10/02)
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- Cyclobutylidenes from Geminal Dihalogenocyclobutanes
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Cyclobutylidene, or a related carbenoid, can be generated by reaction of geminal dibromocyclobutane with methyl-lithium at temperatures as low as -78 deg C to yield methylenecyclopropane and cyclobutene nearly quantitatively.
- Brinker, Udo H.,Schenker, Gilbert
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p. 679 - 681
(2007/10/02)
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- Influence de la taille du cycle sur la substitution electrophile des cycloalkyltrimethylsilanes. Synthese de cycloalkyldimethylfluorosilanes
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Cycloalkyltrimethylsilanes, excepting cyclopropyl-, react with electrophiles by Si - Me bond splitting.Consequently silicon can be functionalized by this route.We also propose a new synthesis of cycloalkyldimethylfluoro(or chloro-)silanes.In the case of five or six member ring derivates, the observed results are interpreted by a mechanism involving initial abstraction of hydride ion from the silicon substrate.
- Grignon-Dubois, M.,Dunogues, J.,Calas, R.
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p. 291 - 295
(2007/10/02)
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- Stereochemistry of acid-catalyzed cleavage of 3-chloro- and 3-bromonortricyclene in deuterated medium. Evidence for edge protonation of nortricyclenes
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Cleavage of 3-chloronortricyclene (4c) and 3-bromonortricyclene (4d) occurs faster than solvolysis in D2SO4-DOAc at 70-75 deg C and yields syn-7-, anti-7-, exo-5-, and endo-5-halo-exo-2-norbornyl acetates as products.That the 7-chloroacetates comprise 70percent of the reaction mixture, that 30percent of the 5-chloro-exo-2-norbornyl acetates which comprised 28percent of the reaction mixture are derived via rearrangement of the syn-7- and anti-7-chloronorbornyl cations, and that the deuterium at C-6 is at least 90percent stereochemically pure endo is evidence that cleavage of the bond farthest removed from the electron withdrawing halogen is preferred 5:1 over the other bonds of the three-membered ring.The stereochemistry of the ring-opening is rationalized on the basis of cleavage via edge-deuteronation with formation of classical halocations as intermediates.The location of deuterium in the 5-halo-exo-norbornyl acetates is used to define the pathways whereby the 5-haloacetates are formed.This study also establishes that C-6 endo deuterated 7-chloro- and 7-bromo-exo-2-norbornyl brosylates can be synthesized from the corresponding 3-halonortricyclenes.
- Werstiuk, Nick Henry,Timmins, George,Cappelli, Frank Peter
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p. 1709 - 1724
(2007/10/02)
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