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Search for "hydride" in Full Text gives 482 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Synthesis, biophysical properties, and RNase H activity of 6’-difluoro[4.3.0]bicyclo-DNA

  • Sibylle Frei,
  • Adam K. Katolik and
  • Christian J. Leumann

Beilstein J. Org. Chem. 2019, 15, 79–88, doi:10.3762/bjoc.15.9

Graphical Abstract
  • the presence of persilylated thymine to produce the iodine intermediates 2α/β (Scheme 1, Table 1, entry 1). These instable intermediates were then directly reduced with tributyltin hydride (Bu3SnH) to yield the tricyclic nucleosides 5α/β as main compounds. However, we observed the occurrence of the
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Published 08 Jan 2019

Regioselective addition of Grignard reagents to N-acylpyrazinium salts: synthesis of substituted 1,2-dihydropyrazines and Δ5-2-oxopiperazines

  • Valentine R. St. Hilaire,
  • William E. Hopkins,
  • Yenteeo S. Miller,
  • Srinivasa R. Dandepally and
  • Alfred L. Williams

Beilstein J. Org. Chem. 2019, 15, 72–78, doi:10.3762/bjoc.15.8

Graphical Abstract
  • recently showed that 3-alkoxy-substituted N-acylpyrazinium salts can be selectively reduced by tributyltin hydride to afford 1,2-dihydropyrazines in good to excellent yields [9]. There have been other reports involving the addition of TMS-ketene acetals to pyrazinium salts [10][11][12]. A double
  • , Table 1). Changing the solvent to diethyl ether showed no improvement in the yield of 3a but when THF was used, an excellent yield of 87% was produced (entries 4 and 5, Table 1). Based on our previously developed selective tin hydride reduction of monosubstituted pyrazinium salts [9], we expected the
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Published 08 Jan 2019

A simple and effective preparation of quercetin pentamethyl ether from quercetin

  • Jin Tatsuzaki,
  • Tomohiko Ohwada,
  • Yuko Otani,
  • Reiko Inagi and
  • Tsutomu Ishikawa

Beilstein J. Org. Chem. 2018, 14, 3112–3121, doi:10.3762/bjoc.14.291

Graphical Abstract
  • solution [38] (run 2 in Table 1) and with Me2SO4 and K2CO3 in 0.023 M solution [39] (run 3 in Table 1) afforded 1 in 86% and 72% yields, respectively. In the remaining reaction the use of sodium hydride (NaH) as a base produced 1 in 84% yield [40] (run 4 in Table 1). We at first re-examined these reactions
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Published 28 Dec 2018

A convenient and practical synthesis of β-diketones bearing linear perfluorinated alkyl groups and a 2-thienyl moiety

  • Ilya V. Taydakov,
  • Yuliya M. Kreshchenova and
  • Ekaterina P. Dolotova

Beilstein J. Org. Chem. 2018, 14, 3106–3111, doi:10.3762/bjoc.14.290

Graphical Abstract
  • dispersion in native form [18][19][25], we have found that mineral oil should be removed before the synthesis. The results of the optimization experiments are summarized in Table 1. The safest way to remove oil is by washing sodium hydride by means of decantation directly in the reaction flask. This
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Published 27 Dec 2018

6’-Fluoro[4.3.0]bicyclo nucleic acid: synthesis, biophysical properties and molecular dynamics simulations

  • Sibylle Frei,
  • Andrei Istrate and
  • Christian J. Leumann

Beilstein J. Org. Chem. 2018, 14, 3088–3097, doi:10.3762/bjoc.14.288

Graphical Abstract
  • persilylated thymine in the presence of NIS (Scheme 2), followed by radical reduction of the iodide intermediate with tributyltin hydride (Bu3SnH) generated an anomeric mixture of nucleoside 6α/β with the β-anomer as major component (α/β ratio = 1:4.5 according to 1H NMR). The inseparable anomers of nucleoside
  • the nucleobase was conducted by 1H,1H-ROESY experiments (Supporting Information File 1). The β-anomer 7β then was subjected to Luche reduction [55][56] producing selectively the desired S-configuration at the C(5’) position due to hydride delivery from the less hindered exo-side of the carbonyl group
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Published 20 Dec 2018

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion

  • Rudolf Knorr and
  • Barbara Schmidt

Beilstein J. Org. Chem. 2018, 14, 3018–3024, doi:10.3762/bjoc.14.281

Graphical Abstract
  • preponderant product) may be encountered when the deprotonating base is added to the alcohol 13 either too slowly or in a less than stoichiometric amount. For instance (bottom line of Scheme 3), the heterogeneous, slow deprotonation of 13 in THF by the insoluble base potassium hydride (KH) afforded 11 and 1 as
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Published 11 Dec 2018

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

  • Christiane Schultze and
  • Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

Graphical Abstract
  • catalyst A in dichloromethane at ambient temperature, higher dilution and after prolonged reaction time. For the synthesis of furanocoumarins 3 the allyl ethers 9 were first subjected to a Ru hydride-catalyzed double bond isomerization [55][56] to furnish enol ethers 10 as inseparable mixtures of
  • subjected to the isomerization conditions previously used for the synthesis of furanocoumarin precursors 10 (see Table 2) we observed no conversion. A plausible explanation is the formation of a stable six-membered Ru–O–chelate complex following hydroruthenation, which inhibits a subsequent β-hydride
  • elimination and thus interrupts the catalytic cycle. For these reasons we started from the MOM-protected 8-allylcoumarins 7, which underwent the Ru-hydride catalyzed double bond migration smoothly. The MOM group was cleaved off without isolation of the intermediate products and the required 7-hydroxy-8-(prop
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Published 05 Dec 2018

Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step

  • Pierre-Antoine Nocquet,
  • Aurélie Macé,
  • Frédéric Legros,
  • Jacques Lebreton,
  • Gilles Dujardin,
  • Sylvain Collet,
  • Arnaud Martel,
  • Bertrand Carboni and
  • François Carreaux

Beilstein J. Org. Chem. 2018, 14, 2949–2955, doi:10.3762/bjoc.14.274

Graphical Abstract
  • obtained for the desired products due to the formation of substantial amounts of ring-opened byproducts 10 resulting from the hydride addition to the carbonyl group of the oxazolidinone ring [33][34]. The alcohols 9 were then subjected to a Swern oxidation followed by a Wittig reaction to generate the
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Published 29 Nov 2018

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

  • Glwadys Gagnot,
  • Vincent Hervin,
  • Eloi P. Coutant,
  • Sarah Desmons,
  • Racha Baatallah,
  • Victor Monnot and
  • Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

Graphical Abstract
  • -amino esters, we tried their preparation via a C-methylation of α-nitroester 6a in DMF using sodium hydride and methyl iodide. Upon purification, this gave 46% of the nitro compound 9 with 94% purity (as assessed by 1H NMR). Despite this modest yield, the ensuing reduction using zinc and hydrochloric
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Published 15 Nov 2018

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

  • Iveta Tichá,
  • Gábor Benkovics,
  • Milo Malanga and
  • Jindřich Jindřich

Beilstein J. Org. Chem. 2018, 14, 2829–2837, doi:10.3762/bjoc.14.261

Graphical Abstract
  • introduced by Sinaÿ et al. [10] and continued in the studies by Sollogoub et al. [11][12]. The addition of diisobutylaluminum hydride (DIBAL-H) to perbenzylated CDs exclusively formed a single AD regioisomer on the primary rim of α-CD. Conversely, the direct, straightforward modification is mostly performed
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Published 13 Nov 2018

Carbonylonium ions: the onium ions of the carbonyl group

  • Daniel Blanco-Ania and
  • Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2018, 14, 2568–2571, doi:10.3762/bjoc.14.233

Graphical Abstract
  • replacement of carbon atoms by the heteroatoms oxygen, nitrogen and sulfur, respectively. Thus, “oxacarbenium ion” would denote a carbenium ion whose carbon atom is replaced by an oxygen atom, that is, an oxonium ion (3; Figure 2). Although if a coherent structure by formal subtraction of hydride from the
  • ” (divalent carbon atom bound to a parent hydride) and “oxonium ion” (or “oxidanium ion”) forming “carbenoxonium ions” (or “carbenoxidanium ions”). These other terms are as long as the names currently used in the literature commented above, but they lack the stem of the functional group they come from and
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Commentary
Published 04 Oct 2018

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

  • Nicholas G. Jentsch,
  • Jared D. Hume,
  • Emily B. Crull,
  • Samer M. Beauti,
  • Amy H. Pham,
  • Julie A. Pigza,
  • Jacques J. Kessl and
  • Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

Graphical Abstract
  • synthesis method through the one-pot acylation of ethyl acetoacetate with isatoic anhydrides followed by dehydrative intramolecular cyclization to access the desired quinoline scaffold 10 [18]. We replaced sodium hydride as the base required to generate the enolate of ethyl acetoacetate with sodium
  • hydroxide [19][20]. The use of sodium hydride is of particular concern upon reaction scale-up due to limited solubility in organic solvents and the production of flammable hydrogen gas [21][22]. Sodium hydroxide avoids the off-gassing of hydrogen and produces water instead, thereby avoiding the use of any
  • intramolecular 6-exo-trig cyclization and subsequent proton transfer to the aminal oxygen D. Elimination of the 2-hydroxy group from D then affords the 4-quinolone E that tautomerizes via [1,5]-hydride shift to form quinoline 10. Given the success of employing ethyl acetoacetate in the quinoline
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Published 28 Sep 2018

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

  • Tetsuaki Fujihara and
  • Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

Graphical Abstract
  • mechanism for this transformation. First, transmetalation between the Rh(I) and Zn reagents generates ethyl–Rh(I) species A, from which β-hydrogen elimination occurs to yield the hydride-Rh intermediate B (step a). Subsequently, the hydrorhodation of the C–C double bond occurs, affording an alkyl-Rh(I
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Published 19 Sep 2018

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

  • Pamarthi Gangadhar,
  • Sayini Ramakrishna,
  • Ponneri Venkateswarlu and
  • Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

Graphical Abstract
  • -selective reduction [25] of alkyne 20 was easily achieved with sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al) as a hydride-transfer reagent to furnish the corresponding (E)-allylic alcohol 23. A Swern oxidation of 23 provided the corresponding aldehyde which was subjected to an addition reaction with
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Published 04 Sep 2018

One-pot synthesis of epoxides from benzyl alcohols and aldehydes

  • Edwin Alfonzo,
  • Jesse W. L. Mendoza and
  • Aaron B. Beeler

Beilstein J. Org. Chem. 2018, 14, 2308–2312, doi:10.3762/bjoc.14.205

Graphical Abstract
  • benzyl alcohol (1) in the presence of slight excess of tetrafluoroboric acid in diethyl ether (HBF4·Et2O) and tetrahydrothiophene (THT). Notably, the use of acetonitrile (MeCN) as a solvent was critical for maintaining a homogeneous reaction and a successful outcome. We also observed that sodium hydride
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Published 03 Sep 2018

The enzymes of microbial nicotine metabolism

  • Paul F. Fitzpatrick

Beilstein J. Org. Chem. 2018, 14, 2295–2307, doi:10.3762/bjoc.14.204

Graphical Abstract
  • solvent isotope effects established that the reaction catalyzed by LHNO is the same as other flavin amine oxidases, direct hydride transfer from the uncharged amine to the flavin (Scheme 4) [19][20]. Hydrolysis to form 6-hydroxypseudooxynicotine occurs in solution after release of the oxidized amine from
  • bond of the substrate methyl group by hydride transfer [40]. The resulting 4-aminobutryrate is likely a substrate for a chromosomally-encoded aminotransferase, producing α-ketoglutarate and succinate semialdehyde. Mao (γ-N-methylaminobutyrate oxidase) contains noncovalently-bound flavin and catalyzes
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Published 31 Aug 2018

Hydroarylations by cobalt-catalyzed C–H activation

  • Rajagopal Santhoshkumar and
  • Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

Graphical Abstract
  • strategies, remote C4-selective alkylation of pyridines [74] was also feasible with alkenes as Kanai et al. reported (Scheme 24a) [75]. The addition of pyridine (34) to alkenes in the presence of 1 mol % CoBr2, 20 mol % BEt3, and LiBEt3H as a hydride source provided branched-selective products 35a with
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Published 29 Aug 2018
Graphical Abstract
  • ]. Mechanistic studies showed that Et3SiH participates in the formation of a cobalt hydride intermediate that delivers a hydrogen atom to the less-substituted position of the alkene. The resulting alkyl radical is believed to abstract a second hydrogen atom from DHB to generate the reduced product [2]. This
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Published 28 Aug 2018

Synthesis of 1,4-imino-L-lyxitols modified at C-5 and their evaluation as inhibitors of GH38 α-mannosidases

  • Maroš Bella,
  • Sergej Šesták,
  • Ján Moncoľ,
  • Miroslav Koóš and
  • Monika Poláková

Beilstein J. Org. Chem. 2018, 14, 2156–2162, doi:10.3762/bjoc.14.189

Graphical Abstract
  • pyridine or TEA was sluggish. Subsequent substitution of the tosylate in 8 either with Super-hydride® (LiBHEt3) or with a cuprate generated in situ from MeMgBr and CuI afforded pyrrolidines 9 [31] and 12 in 68% and 44% yield, respectively (Scheme 1). In the course of tosylate substitution with the cuprate
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Published 17 Aug 2018

An amine protecting group deprotectable under nearly neutral oxidative conditions

  • Shahien Shahsavari,
  • Chase McNamara,
  • Mark Sylvester,
  • Emily Bromley,
  • Savannah Joslin,
  • Bao-Yuan Lu and
  • Shiyue Fang

Beilstein J. Org. Chem. 2018, 14, 1750–1757, doi:10.3762/bjoc.14.149

Graphical Abstract
  • , the dM-Dmoc group is expected to be more stable under nucleophilic conditions, which will allow many transformations including base hydrolysis of esters and amides, hydride reduction of carbonyl compounds, and a wide range of nucleophilic substitution reactions to be carried out without losing the
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Published 13 Jul 2018

Visible light-mediated difluoroalkylation of electron-deficient alkenes

  • Vyacheslav I. Supranovich,
  • Vitalij V. Levin,
  • Marina I. Struchkova,
  • Jinbo Hu and
  • Alexander D. Dilman

Beilstein J. Org. Chem. 2018, 14, 1637–1641, doi:10.3762/bjoc.14.139

Graphical Abstract
  • proposed mechanism is shown in Scheme 2. First, difluorinated iodide 1 interacts with boron hydride to form a small equilibrium concentration of a halogen-bonded complex [49][50]. This complex is activated by light to effect homolytic cleavage of the carbon–iodine bond with the formation of radical 4 and
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Published 02 Jul 2018

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

  • Yuichi Yoshimura,
  • Hideaki Wakamatsu,
  • Yoshihiro Natori,
  • Yukako Saito and
  • Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

Graphical Abstract
  • by manipulations of 5. After acetal hydrolysis and the subsequent hydride reduction, 4-thioarabinose derivative 9 was obtained in good yield. Introduction of a TBDPS group at the primary hydroxy group of 9, oxidation and Wittig reaction, followed by deprotection of the benzyl group, gave allyl
  • by intramolecular SN2 reaction at the 5-position by sulfur atom. Secondary, ring contraction from thiopyranose to thiofuranose occurred to produce 5-aldehyde 26. Finally, hydride reduction of 26 gave the 4-thiofuranose derivative 27. The Pummerer-type glycosylation reaction of 5-O-silylated sulfoxide
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Published 28 Jun 2018

Recent applications of chiral calixarenes in asymmetric catalysis

  • Mustafa Durmaz,
  • Erkan Halay and
  • Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

Graphical Abstract
  • sodium hydride in tetrahydrofuran and subsequent deprotection of Boc groups afforded L-proline immobilized calix[4]arene magnetic nanoparticles (Calix-Pro-MN) 86 (Scheme 23). In 2016, three new lower rim functionalized calix[4]arene-based L-proline catalysts 87–89 containing ester, amide and acid units
  • derivatives using R-(−)-2-methylbutanol as hydride source [71]. As shown in Scheme 34, independent of which calix[4]arene diastereomer (111 or 112) was employed, when ortho-fluorobenzophenone was used as substrate, the enantioselectivity remained at 20%. But the MPV enantioselectivity was found sensitive to
  • was used as a hydride donor. The data for MPV reduction of 113a at room temperature showed that the enantioselectivity was highly dependent on the steric bulk of catalyst (Scheme 36). Enantioselectivity of the reduction increased up to 20% when lower-rim substituent changed from α-phenylmethyl in 115a
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Published 08 Jun 2018

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

  • Anna Czarnecka,
  • Emilia Kowalska,
  • Agnieszka Bodzioch,
  • Joanna Skalik,
  • Marek Koprowski,
  • Krzysztof Owsianik and
  • Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

Graphical Abstract
  • diarylmethyl alcohols with hydride sources. These reactions require a preliminary C–OH bond activation by Brønsted or Lewis acids. Several reagent systems have recently been employed to achieve this goal, including: NaBH4–CF3COOH [26], ZnI2–NaBH3CN [27], HI–Pred [28], H3PO2–I2 [29][30], Mo(CO)6-Lawesson’s
  • hydride donors, such as NaBH4 and LiAlH4 in various combinations with ZnI2 and AlCl3 failed [61][62][63]. For instance, the reaction with NaBH4 itself and NaBH4/ZnI2/THF at room temperature and reflux only recovered the substrates. The same result was obtained at room temperature with NaBH4/AlCl3/THF
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Published 29 May 2018

One hundred years of benzotropone chemistry

  • Arif Dastan,
  • Haydar Kilic and
  • Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

Graphical Abstract
  • of p-toluenesulfonic acid (p-TsOH), the reduction of 175 with lithium aluminum hydride afforded the intermediate 176, which was converted to 2,3-benzotropone (12) under acidic conditions. 3.2. Reactions of 2,3-benzotropone (12) 3.2.1. Reactions via a carbonyl group: Among the most common reactions
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Published 23 May 2018
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