- Highly disordering nanoporous frameworks of lanthanide-dicarboxylates for catalysis of CO2 cycloaddition with epoxides
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A series of nanoporous [LnIII4(di-nitro-BPDC)4(NO2)3(OH)(H2O)5]·n(methanol) (LnIII ?= ?PrIII, NdIII, SmIII, EuIII, GdIII, PrIII/GdIII and PrIII/EuIII; di-nitro-BPDC2- ?= ?2,2′-dinitrobiphenyl-4,4′-dicarboxylate) was synthesized and characterized. Founded on Lewis acidic LnIII possessing vacant coordination sites and functional groups of di-nitro-BPDC2-, their catalytic activities were evaluated based on the CO2 cycloaddition reactions with epoxides under ambient pressure and solvent-free conditions. Depending on catalytic conditions, satisfying turnover number and turnover frequency of 1106 and 276 h-1, respectively, could be yielded with ≥79(±4)% conversion and 87(±1)% selectivity. The correlation between the catalysis performance and structural factors is proposed on a basis of experimental and computation results. These include the restrained transportation even in the nanoporous framework and crystallographic disorder in the LnIII coordination environment. The excellent robustness of the catalysts, effects of lanthanide contraction, and synergistic activities of the heterometallic PrIII/GdIII and PrIII/EuIII catalysts are also included.
- Chiangraeng, Natthiti,Konno, Takumi,Kuwamura, Naoto,Nimmanpipug, Piyarat,Rujiwatra, Apinpus,Thammakan, Supaphorn
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- Asymmetric Synthesis of Functionalized trans-Cyclopropoxy Building Block for Grazoprevir
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A practical and asymmetric synthesis of a functionalized trans-cyclopropoxy building block for the preparation of the HCV NS3/4a protease inhibitor grazoprevir is reported. Intramolecular SN2 displacement-ring closure, followed by a Baeyer-Villiger oxidation, yields the desired trans-cyclopropanol with full control of diastereoselectivity. A terminal alkyne is then effectively installed using LiNH(CH2)2NEt2. Starting from (S)-epichlorohydrin, the cyclopropoxy building block is prepared in 51% overall yield with >99.8% optical purity without isolation of any intermediates.
- Xu, Feng,Zhong, Yong-Li,Li, Hongming,Qi, Ji,Desmond, Richard,Song, Zhiguo J.,Park, Jeonghan,Wang, Tao,Truppo, Matthew,Humphrey, Guy R.,Ruck, Rebecca T.
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supporting information
p. 5880 - 5883
(2017/11/10)
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- Trihaloisocyanuric Acid/Triphenylphosphine: An Efficient System for Regioselective Conversion of Epoxides into Vicinal Halohydrins and Vicinal Dihalides under Mild Conditions
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A new synthetic method has been developed for the regioselective conversion of epoxides to vicinal chloro-/bromohydrins and vicinal dihalides by reaction with the system trihaloisocyanuric acid/tri?phenylphosphine in acetonitrile under mild and neutral conditions. The reactions proceed smoothly in high yield at room temperature and at reflux, respectively, over a short time.
- De Andrade, Vitor S. C.,De Mattos, Marcio C. S.
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p. 1381 - 1388
(2016/05/19)
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- 1,3,2,4-diazadiphosphetidine-based phosphazane oligomers as source of P(III) atom economy reagents: Conversion of epoxides to vic -haloalcohols, vic -dihalides, and alkenes in the presence of halogen sources
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1,3,2,4-Diazadiphosphetidines (P1-P3), as easily prepared, stable, and heterogeneous P(III) compounds, were used for the efficient conversion of epoxides to vic-halohydrins, vic-dihalides, or alkenes in the presence of different halogen sources in CH3CN. Of these phosphazanes, P3 is most suitable and contains 4 phosphorous atoms with the advantage of having greater atom economy and its phosphorus oxide byproduct can be easily separated from the reaction mixture by simple filtration. The nitrogen atoms in this molecule can also act as acid scavengers in the reaction.
- Iranpoor, Nasser,Firouzabadi, Habib,Etemadidavan, Elham
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p. 1165 - 1173
(2014/10/16)
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- Synthesis of Di-, Tri-, and tetrasubstituted oxetanes by rhodium-catalyzed O-H insertion and C-C bond-forming cyclization
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Oxetanes offer exciting potential as structural motifs and intermediates in drug discovery and materials science. Here an efficient strategy for the synthesis of oxetane rings incorporating pendant functional groups is described. A wide variety of oxetane 2,2-dicarboxylates were accessed in high yields, including functionalized 3-/4-aryl-and alkyl-substituted oxetanes and fused oxetane bicycles. Enantioenriched alcohols provided enantioenriched oxetanes with complete retention of configuration. The oxetane products were further derivatized, while the ring was maintained intact, thus highlighting their potential as building blocks for medicinal chemistry.
- Davis, Owen A.,Bull, James A.
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supporting information
p. 14230 - 14234
(2015/02/19)
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- Mild organic ammonium tribromide-mediated regioselective ring opening of epoxides with alcohols, water, acetic anhydride, and amines under solvent-free reaction conditions
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Organic ammonium tribromide (OATB), N-methylpyrrolidine-2-one hydrotribromide (MPHT) was found to be an efficient catalyst for the regioselective ring opening of epoxides with various nucleophiles under solvent free conditions. This procedure occurs under neutral and mild reaction conditions with out adding any additive and afforded high yields of products.
- Singhal, Sweety,Jain, Suman L.,Sain, Bir
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experimental part
p. 1829 - 1837
(2011/06/19)
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- Synthesis of benzodioxepinone analogues via a novel synthetic route with qualitative olfactory evaluation
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Marine odorants represent a minor yet diverse class of substances within the fragrance industry, of which 7-methyl-2H-1,5-benzodioxepin-3(4H)-one (1) is commercially known as Calone 1951, a synthetic first in the area of marine-fragrance chemistry. To determine the extent to which the characteristic marine odor of Calone 1951 corresponds to the substitution at the benzo portion of the molecule, a variety of aromatic substituents were incorporated into the benzodioxepinone structure (Scheme 1, Table 3). In light of the difficulty experienced in applying patented literature to deriving the analogues 12-18, particularly those with electron-withdrawing substituents, an alternative synthetic scheme was implemented for the construction of all analogues in favorable yields (Scheme 4, Table 3). Formation of the hydroxy-protected dihalo alkylating agent 24 via epoxide cleavage of epichlorohydrin (Scheme 3) allowed etherification favoring dihalo displacement and subsequent intramolecular ring closure (-→26a-g). THP Deprotection followed by oxidation of the alcohols 27a-g to the ketones 12-18 provided a general pathway to the benzodioxepinone products. The influence of the substituent nature on odor activity revealed a diverse scope of olfactory character (Table 4).
- Drevermann, Britta,Lingham, Anthony R.,Huegel, Helmut M.,Marriott, Philip J.
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p. 1006 - 1027
(2008/02/04)
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- Monobromoborane-dimethyl sulfide - A highly promising reagent for the regio- and chemoselective brominative cleavage of terminal epoxides into vicinal bromohydrins
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Monobromoborane?dimethyl sulfide (BH2Br?SMe2) is a highly regio- and chemoselective reagent useful for the brominative cleavage of the epoxy moiety into bromohydrins in the presence of alkenes, alkynes, ethers, acetals, ketals, and acetonides at 0°C, besides being an excellent hydroborating reagent. Several reactive functional groups, such as chloride, ketones, esters, nitriles, nitros, and thioethers, have been accommodated during such transformations. Although the reduction of acetophenone was completely suppressed at ?25°C, 4-chlorobenzaldehyde still underwent 12?13% reduction of an aldehydic group. CSIRO 2007.
- Roy, Chandra D.,Brown, Herbert C.
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p. 139 - 145
(2008/02/11)
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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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- 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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p. 169 - 174
(2007/10/03)
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- Dimethoxyboron bromide - A new, efficient, regio- and chemoselective reagent for the conversion of terminal epoxides into bromohydrins
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Dimethoxyboron bromide, (MeO)2BBr, easily prepared in excellent yield from boron tribromide and trimethyl borate, is a new, efficient, regio- and chemoselective reagent useful for the halogenative cleavage of compounds containing epoxy groups into vicinal bromohydrins in the presence of ether, acetal, ketal, N-oxide, and sulfoxide groups, at low temperatures (-78°C).
- Roy, Chandra D.,Brown, Herbert C.
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p. 639 - 641
(2007/10/03)
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- Ionic liquid as reagent. A green procedure for the regioselective conversion of epoxides to vicinal-halohydrins using [AcMIm]X under catalyst- and solvent-free conditions
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A variety of structurally diverse epoxides undergo facile cleavages by ionic liquid, [AcMIm]X without any catalyst and solvent to produce the corresponding vicinal halohydrins in high yields. The cleavages are considerably fast and highly regioselective.
- Ranu, Brindaban C.,Banerjee, Subhash
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p. 4517 - 4519
(2007/10/03)
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- o-Phenylenediamine as a new catalyst in the highly regioselective conversion of epoxides to halohydrins with elemental halogens
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The regioselective ring opening of epoxides using elemental iodine and bromine in the presence of o-phenylenediamine as a new catalyst affords vicinal iodo alcohols and bromo alcohols in high yields. The major advantages of this method are versatility, high regioselectivity, a cheap and commercially available catalyst, mild and neutral reaction conditions, and short reaction times. Fourier transform Raman spectroscopy was used to study the reaction of iodine with o-phenylenediamine. The results indicate that the complex [(Diamine)I]+·I5- is formed, and we suggest that the major nucleophile is the pentaiodide ion. This bulky nucleophile has a fundamental role in the high regioselectivity observed attacking the less sterically hindered epoxide carbon. Springer-Verlag 2004.
- Eshghi, Hossein,Tayyari, Sayyed Faramarz,Sanchuli, Esmaiel
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p. 1101 - 1111
(2007/10/03)
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- Conversion of epoxides into halohydrins with elemental halogen catalyzed by thiourea
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A highly regioselective method for the synthesis of β-iodohydrins and β-bromohydrins by the direct ring opening of epoxides with elemental halogen in the presence of thiourea is described. This method occurs under neutral and mild conditions with high yields in various solvents even when sensitive functional groups are present.
- Sharghi, Hashem,Eskandari, Mohammad Mehdi
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p. 8509 - 8514
(2007/10/03)
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- Highly facile biomimetic regioselective ring opening of epoxides to halohydrins in the presence of β-cyclodextrin
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Highly regioselective ring opening of epoxides to halohydrins has been carried out in impressive yields with hydrogen and lithium halides in presence of β-cyclodextrin using water as solvent.
- Reddy, M.Arjun,Surendra,Bhanumathi,Rao, K.Rama
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p. 6003 - 6008
(2007/10/03)
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- Cleavage of epoxides into halohydrins with elemental iodine and bromine in the presence of 2,6-bis[2-(o-aminophenoxy)methyl]-4-bromo-1-methoxybenzene (BABMB) as catalyst
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The ring opening of epoxides with elemental iodine and bromine in the presence of 2,6-bis[2-(o-aminophenoxy)methyl]-4-bromo-1-methoxybenzene as a new catalyst affords vicinal iodo alcohols and bromo alcohols in high yields. This new procedure occurs regioselectively under neutral and mild conditions in various aprotic solvents even when sensitive functional groups are present.
- Niknam, Khodabakhsh,Nasehi, Taibeh
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p. 10259 - 10261
(2007/10/03)
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- Conversion of epoxides to halohydrins with elemental halogen catalyzed by phenylhydrazine
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The highly regioselective method for the synthesis of β-iodohydrins and β-bromohydrins by the direct ring opening of 1,2-epoxides with elemental halogen in the presence of phenylhydrazine is described. This method occurs under neutral and mild conditions with high yields in various aprotic solvents even when sensitive functional groups are present.
- Sharghi, Hashem,Eskandari, Mohammad Mehdi
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p. 1519 - 1522
(2007/10/03)
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- Studies into reactions of N-methylmorpholine-N-oxide (NMMO) and its hydrates with cyanuric chloride
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The course of the reaction between N-methylmorpholine-N-oxide (NMMO, 1a) and cyanuric chloride (2) is strictly dependent on the hydrate water content of the amine oxide. In solid phase, both substances undergo an explosion-like, extremely exothermic reaction. In solution, this process becomes controllable and leads to a quantitative degradation of NMMO into morpholine and formaldehyde, with 2 only acting as an inducing agent. The reaction can be conducted in a way that a clean deoxygenative demethylation is achieved. The monohydrate of NMMO (1b) is quantitatively converted into N-methylmorpholine and hypochlorous acid by the action of 2. This conversion can be used in synthesis either to deoxygenate tertiary amine N-oxide monohydrates, or to produce chlorohydrins in non-aqueous, organic media in superior yields. The semisesquihydrate of NMMO (1c) reacts with 2 under consumption of water until non-hydrated NMMO is present, which is then further converted into morpholine and HCHO, as in the case of 1a being directly employed as the starting material.
- Rosenau, Thomas,Potthast, Antje,Kosma, Paul
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p. 9809 - 9815
(2007/10/03)
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- Iron(III) trifluoroacetate as an efficient catalyst for solvolytic and nonsolvolytic nucleophilic ring opening of epoxides
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Iron(III) trifluoroacetate was used as an efficient and nonhygroscopic catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides. The addition of chloride, bromide, iodide, and nitrate ions to epoxides to produce the corresponding 2-halo and 2-nitratoalkanols and also the conversion of epoxides to acetonides and thiiranes were also performed efficiently in the presence of this catalyst.
- Iranpoor, Nasser,Adibi, Hadi
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p. 675 - 680
(2007/10/03)
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- Metalloporphyrins as New Catalysts in the Highly Regioselective Conversion of Epoxides to Halohydrins with Molecular Halogen
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The halogenative cleavage of epoxides occurs by addition of molecular iodine and bromine in the presence of catalytic amount of metalloporphyrins under mild conditions in various aprotic solvents. The corresponding vicinal iodohydrins and bromohydrins were obtained with highly regioselectivity in high yields.
- Sharghi, Hashem,Naeimi, Hossein
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p. 1357 - 1372
(2007/10/03)
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- Solvent-free organic reactions on silica gel supports. Facile transformation of epoxides to β-halohydrins with lithium halides
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The reaction of epoxides with lithium halides was efficiently promoted on the surface of silica gel in the absence of any solvent to give the corresponding β-halohydrins. The reactivity of lithium halides was shown to follow the order LiI > LiBr >> LiCl, and the reactivity of LiCl was dramatically increased by adding an equivalent amount of water to this system. On the other hand a similar reaction with α,β-epoxyketones produces the α-haloenone derivatives, presumably via halohydrin intermediates. The epoxide-opening reaction of (R)-(+)-styrene oxide was also investigated to clarify the stereochemical features of this reaction.
- Kotsuki, Hiyoshizo,Shimanouchi, Tomoyasu,Ohshima, Reiji,Fujiwara, Shunsuke
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p. 2709 - 2722
(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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- FeCl3·6H2O supported on SiO2 catalysed ring opening of epoxides with alcohols, acetic acid, water, chloride, bromide and nitrate ions
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FeCl3·6H2O absorbed on chromatographic silica gel can act as an efficient catalyst for alcoholysis, hydrolysis and acetolysis of epoxides. Methanolysis of (R)-styrene oxide proceeds with high stereospecificity and in excellent yield. This catalyst can also convert epoxides to their corresponding β-halohydrins and β-nitrato alcohols in the presence of chloride, bromide and nitrate ions respectively.
- Iranpoor, Nasser,Tarrian, Tahere,Movahedi, Zarangiz
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p. 1473 - 1476
(2007/10/03)
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- A facile conversion of epoxides to β-halohydrins with silica gel-supported lithium halides
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A variety of epoxides are efficiently converted to the corresponding β-halohydrins with lithium halides supported on silica gel in dry media.
- Kotsuki, Hiyoshizo,Shimanouchi, Tomoyasu
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p. 1845 - 1848
(2007/10/03)
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- Efficient routes to isotopically labelled epichlorohydrins ((chloromethyl) oxiranes)
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Efficient routes are developed for the synthesis of variously labelled 2H- and 13C- labelled epichlorohydrins prepared from appropriately labelled acetic acids and sodium borodeuteride. The route is versatile and can be used for strategic location of isotopes at C-I, C-2 and C-3 of epichlorohydrin. By way of demonstration [2-13C]-, [2-2H]-, [3-2H2] and [2-2H, 3-2H2]-epithlorohydrins have been prepared. In addition the syntheses can be adapted for the preparation of enantiomerically pure and isotopically labelled epichlorohydrins.
- O'Hagan,White,Jones
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p. 871 - 880
(2007/10/02)
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- Selective Additions of Gaseous Hydrochloric Acid to Crystalline Epoxides und Steroid-Epoxides
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Solid epoxides add gaseous HCl or KBr regioselectively and without melting, if the melting points are sufficiently high.Such additions proceed diastereoselectively with chiral epoxides.These gas/solid reactions are compared to similar transformations in solution.One observes interesting reaction sequences in the conversions of steroidal epoxides.Thus the opening of the epoxide ring may be followed by cationic rearrangements, or it occurs elimination od water, if it creates conjugation to a carbonyl group.
- Kaupp, Gerd,Ulrich, Anke,Sauer, Gerhard
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p. 383 - 390
(2007/10/02)
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- An Easy and Efficient Epoxide Opening to give Halohydrins using Tin(II) Halides
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Epoxides are readily converted into halohydrins by tin(II) halides in a variety of solvents.
- Einhorn, Cathy,Luche, Jean-Louis
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p. 1368 - 1369
(2007/10/02)
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