- Cycloaddition of carbon dioxide to 1,2-epoxypropane catalyzed by tetra-t-butylphthalocyaninatoaluminium(III) hydroxide
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Carbon dioxide was fixed as propane-1,2-diol carbonate (PDC) with 1,2-epoxypropane (EP) catalyzed by Al(OH) {pc(t-Bu)4} in the presence of such a quaternary ammonium halide (HAX) as [HO(CH2)2N(CH3)2(C4H 9)]X (X=Cl, Br, I). Although the yield was scarcely affected by the structure of HAX, it was dependent on the kind of halide ion. While PDC was formed in chloroform or dichloromethane, the yield decreased extremely in DMSO or pyridine, and PDC was not prepared in methanol. Although halohydrin was formed in a chloroform solution of EP, Al(OH){pc(t-Bu)4}, and HAX, it was not an intermediate. The formation of a hexa-coordinate complex of Al(OH){pc(t-Bu)4} with HAX and EP was spectroscopically confirmed, and the complex catalyzed the preparation of PDC from carbon dioxide and EP.
- Kasuga, Kuninobu,Kato, Takao,Kabata, Naohiko,Handa, Makoto
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- Reinvestigation of the conversion of epoxides into halohydrins with elemental halogen catalysed by thiourea
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In contrast to a previous literature report, thiourea is not a catalyst in the ring opening reaction of epoxides by means of bromine or iodine. Instead, thiourea reacts with the halogen to give a complex mixture of products, among them hydrogen halogenides, which are in fact the real epoxide ring opening reactants. The presence of water is crucial in this reaction.
- Soroka, Miros?aw,Goldeman, Waldemar
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- O-phenylenediamine as a new catalyst in the highly regioselective conversion of epoxides to halohydrins with elemental halogens - A reinvestigation
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In contrast to a previous report, o-phenylenediamine is not a catalyst in the ring opening reaction of epoxides by means of bromine or iodine. The o-phenylenediamine is just a reactant which reacts with iodine to give phenazine-2,3-diamine and hydrogen iodide, or with bromine to give a mixture of brominated and polymerized products as well as hydrogen bromide. The hydrogen halogenides are in fact the real epoxide ring opening reactants. Springer-Verlag 2006.
- Soroka, Miroslaw,Goldeman, Waldemar
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- Aliphatic carboxylic acid as a hydrogen-bond donor for converting CO2and epoxide into cyclic carbonate under mild conditions
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The coupling of CO2 and epoxides is a promising way to reduce atmospheric carbon by converting it into value-added cyclic carbonate. Pursuing efficient catalysts is highly attractive for the title reaction. Herein, we developed simple and inexpensive catalyst systems of aliphatic carboxylic acids as the hydrogen-bond donor (HBD) and quaternary ammonium halides as the nucleophile to catalyze the CO2-epoxide coupling reaction with high efficiency and selectivity under mild conditions (80 °C and 4 bar CO2). The high activity of this catalyst system is retained even under ambient conditions. The effects of the acidity and steric hindrance of acids on the catalysis of CO2-epoxide coupling were systematically investigated. Lastly, the reaction mechanism was deduced and its rationality was further reinforced by exploring the interaction between a representative system AA/TBAB (acetic acid/tetrabutylammonium bromide) and propylene oxide (PO). The study of aliphatic carboxylic acids/quaternary ammonium halides provides a new way to design catalyst systems for the title reaction.
- Wang, Zheng,Wang, Yajun,Xie, Qianjie,Fan, Zhiying,Shen, Yehua
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- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
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The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
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supporting information
p. 8013 - 8017
(2021/10/25)
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- Method for preparing halogen propanol and epoxypropane
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The invention provides a method for preparing halogen propanol. The method comprises the following steps (1) halogen alcoholization: adding halogen hydride, H2O2, propylene and an HTS molecular sieve into a reaction device, and carrying out halogen alcoholization reaction to obtain the halogen propanol. The invention also provides a method for preparing epoxypropane with a halogenohydrin method. The method comprises the following steps: (1) halogen alcoholization: adding halogen hydride, H2O2, propylene and an HTS molecular sieve into the reaction device, and carrying out the halogen alcoholization reaction to obtain halogen propanol; (2) saponification: carrying out saponification reaction on halogen propanol and a hydroxide of alkali metal in step (1), and separating to obtain the epoxypropane and alkali halide metal salt; optionally (3) electroosmosis: carrying out bipolar membrane electroosmosis on the alkali halide metal salt obtained in step (2) to obtain the hydroxide of alkali metal and the halogen hydride. According to the methods, the halogen propanol or the epoxypropane can be prepared at extremely high selectivity and yield, and the discharging of waste water and waste residues can be drastically lowered.
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Paragraph 0098; 0099; 0110; 0111; 0129; 0130
(2017/05/19)
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- H2TPP organocatalysis in mild and highly regioselective ring opening of epoxides to halo alcohols by means of halogen elements
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We found that elemental iodine and bromine are converted to trihalide nucleophiles (triiodine and tribromide anion, respectively) in the presence of catalytic amounts of meso-tetraphenylporphyrins (H2TPP). Therefore a highly regioselective method for the synthesis of β-haloalcohols through direct ring opening of epoxides with elemental iodine and bromine in the presence of H2TPPs as new catalysts is described. At room temperature a series of epoxide derivatives were converted into the corresponding halohydrins resulting from an attack of trihalide species anion atoms at the less substituted carbon atom. This method occurs under neutral and mild conditions with high yields in various aprotic solvents, even when sensitive functional groups are present.
- Torabi, Parviz,Azizian, Javad,Zomorodbakhsh, Shahab
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experimental part
p. 5508 - 5519
(2012/08/28)
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- NOVEL CONJUGATES, PREPARATION THEREOF, AND THERAPEUTIC USE THEREOF
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Provided herein are cryptophycin conjugates and compositions containing them. Methods of making and using such compounds also are provided
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- Highly regioselective ring opening of epoxides and aziridines using (bromodimethyl)sulfonium bromide
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Epoxides and aziridines undergo ring opening efficiently with (bromodimethyl)sulfonium bromide at room temperature to form the corresponding β-bromohydrins and β-bromoamines, respectively. The conversions are highly regioselective and afford the products in excellent yields within a short period of time.
- Das, Biswanath,Krishnaiah, Maddeboina,Venkateswarlu, Katta
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p. 4457 - 4460
(2007/10/03)
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- Comments on a Conversion of Epoxides to Halohydrins with Elemental Halogen Catalyzed by Phenylhydrazine: Tandem Electrophilic Halogenation of Aromatic Compounds and Epoxide Ring Opening to Halohydrins
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The halogenation of aromatic compounds by bromine or chlorine in the presence of an epoxide gives the corresponding halogenated aromatics and 2-halohydrins, both with good yields.
- Soroka, Miroslaw,Goldeman, Waldemar,Malysa, Piotr,Stochaj, Monika
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p. 2341 - 2344
(2007/10/03)
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- Highly regio- and stereoselective synthesis of β-halohydrins from epoxides catalyzed with ceric ammonium nitrate
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Ce(IV) as ceric ammonium nitrate can effectively catalyze ring opening of epoxides with halides under very mild conditions and easy procedure to give the corresponding β-chloro- and β-bromohydrins in excellent yields. The reactions occur with both substituted and unsubstituted quaternary ammonium halides and with high regio- and stereoselectivity. The reaction of optically active styrene oxide with chloride ion was found to be highly stereospecific and afforded the corresponding β-halohydrin in 96% ee.
- Iranpoor,Kazemi,Salehi
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p. 1247 - 1258
(2007/10/03)
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- Chemo- and Regioselective Reductions of Functionalized Epoxides by Bu3SnH/Bu3SnI-Phosphine Oxide
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A novel reagent, Bu3SnH/Bu3SnI-phosphine oxide, reduced functionalized epoxides to the corresponding alcohols in high chemo- and regioselectivities.
- Kawakami, Takayo,Tanizawa, Daisuke,Shibata, Ikuya,Baba, Akio
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p. 9357 - 9360
(2007/10/02)
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- SULFUR INHIBITORS OF PHOSPHOLIPASE A-Z
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Phospholipase A2 inhibitors having the formula wherein R" is a C2-C20 alkyl group, R1" is a C1-C4 alkyl group, y is an integer from 2 to 10, and J- is a pharmaceutically acceptable anion, are described
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- Highly Regioselective and Stereospecific Functionalization of 1,2-Proanediol with Trimethyl(X)silanes Employing the 1,3,2λ5-Dioxaphospholane Methodology
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The regioselective ring opening of (S)-4-methyl-2,2,2-triphenyl-1,3,2λ5-dioxaphospholanes (2) was initiated with several trimethylsilyl reagents (Me3SiX: X = PhS, I, Br; Cl, CN, and N3) to afford the regioisomeric (silyloxy)phosphonium salts.A stereospecific extrusion of triphenylphosphine oxide from these oxyphosphonium salts gave predominatly the thermodynamically less stable C-2-X-substituted derivatives with nearly complete inversion of stereochemistry at the C-2 stereogenic center (i.e., X = PhS).
- Mathieu-Pelta, Isabel,Evans, Slayton A.
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p. 3409 - 3413
(2007/10/02)
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- Remarkable difference of chemoselectivity in the reduction of α-bromo ketones with dibutyltin dihydride system
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Remarkably different chemoselectivities were noted in the reduction of α-bromo ketones by n-Bu2SnH2 system. Without additive, the reduction of α-bromo group took place. While, the addition of small amounts of p-Dinitrobenzene (DNB) caused the chemoselective reduction of carbonyl group.
- Shibata, Ikuya,Nakamura, Kenji,Baba, Akio,Matsuda, Haruo
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p. 6381 - 6384
(2007/10/02)
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- Catalytic Asymmetric Cyclization of Some Bromohydrins with Chiral Cobalt Complex
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Asymmetric cyclization of a variety of bromohydrins with base was examined in the presence of an optically active cobalt(salen) type complex.Optically active oxiranes of modest optical purities were obtained. erythro-3-Bromo-2-butanol and threo-3-bromo-2-butanol were cyclized similarly, and only trans-2,3-dimethyloxirane and cis-2,3-dimethyloxirane were obtained, respectively, indicating that the cyclization of bromohydrin proceeds by complete SN2 type reaction.
- Takeichi, Tsutomu,Takakura, Teruo,Ishimori, Michihiro,Tsuruta, Teiji
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p. 603 - 605
(2007/10/02)
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- Antihypertensive phosphate derivatives
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Antihypertensive phosphate derivatives having the following formula are described: STR1 wherein X is selected from one or more of: (a) C1 -C24 branched or straight chain alkyl; (b) C1 -C24 branched or straight chain alkoxy; (c) STR2 wherein n and m are integers from 0 to 25 and the sum of n and m is less than or equal to 25; phenyl; substituted phenyl wherein the substituents are selected from the group consisting of C1 -C20 branched or straight chain alkyl, C1 -C20 branched or straight chain alkoxy, halogen, trifluoromethyl, phenyl, and substituted phenyl, phenoxy; and substituted phenoxy, wherein the substituents are selected from the group consisting of C1 -C20 branched or straight chain alkyl, halogen, trifluoromethyl, phenyl and substituted phenyl; Q is selected from the group consisting of: STR3 wherein R1 is selected from the group consisting of hydrogen, C1 -C4 branched or straight chain alkyl, C1 -C4 branched or straight chain alkoxy and C1 -C4 branched or straight chain alkylamino and wherein R3 is C1 -C4 alkyl, with the proviso that when Q is STR4 then R1 is C1 -C4 branched or straight chain alkyl; T is a bivalent radical selected from the group consisting of --(CHR)p -- and STR5 wherein p is an integer from 1 to 15, the moiety --(CHR)p -- represents an alkylene chain substituted at any position with one or more C1 -C10 alkyl groups or phenyl groups, and the moiety STR6 is bound with the oxygen atom attached directly to the aromatic ring; and Z is STR7 wherein R2 is hydrogen or C1 -C4 branched or straight chain alkyl and q is an interger from 4 to 7; in either the racemic or optically active forms.
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- CONVERSION OF EPOXIDES TO BROMOHYDRINS BY B-BROMOBIS(DIMETHYLAMINO)BORANE
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Reaction of the title reagent with 1-alkene oxides regioselectively yields the corresponding 1-bromo-2-alkanols, while the more substituted bromide predominates in the cases of styrene oxide and 1-methylcyclohexene oxide.
- Bell, Thomas W.,Ciaccio, James A.
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p. 827 - 830
(2007/10/02)
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- DILITHIUM TETRABROMONICKELATE (II) AS A SOURCE OF SOFT NUCLEOPHILIC BROMIDE: REACTION WITH EPOXIDES
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Dilithium tetrabromonickelate (II) in THF serves as a source of "soft" nucleophilic bromide and reacts regioselectively with epoxides to give bromohydrins in high yield.
- Dawe, Robert D.,Molinski, Tadeusz F.,Turner, John V.
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p. 2061 - 2064
(2007/10/02)
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