- Oxoammonium-Mediated Allylsilane–Ether Coupling Reaction
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A new C(sp3)?H functionalization reaction consisting of the oxidative α-allylation of allyl- and benzyl- methyl ethers has been developed. The C?C coupling could be carried out under mild conditions thanks to the use of cheap and green oxoammonium salts. The scope of the reaction was studied over 27 examples, considering the nature of the substituents on the two coupling partners.
- Carlet, Federica,Bertarini, Greta,Broggini, Gianluigi,Pradal, Alexandre,Poli, Giovanni
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supporting information
p. 2162 - 2168
(2021/04/02)
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- Highly pH-Dependent Chemoselective Transfer Hydrogenation of α,β-Unsaturated Aldehydes in Water
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The pH-dependent selective Ir-catalyzed hydrogenation of α,β-unsaturated aldehydes was realized in water. Using HCOOH as the hydride donor at low pH, the unsaturated alcohol products were obtained exclusively, while the saturated alcohol products were formed preferentially by employing HCOONa as the hydride donor at high pH. A wide range of functional groups including electron-rich as well as electron-poor substituents on the aryl group of α,β-unsaturated aldehydes can be tolerated, affording the corresponding products in excellent yields with high TOF values. High selectivity and yields were also observed for α,β-unsaturated aldehydes with aliphatic substituents. Our mechanistic investigations indicate that the pH value is critical to the chemoselectivity.
- Luo, Nianhua,Liao, Jianhua,Ouyang, Lu,Wen, Huiling,Liu, Jitian,Tang, Weiping,Luo, Renshi
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p. 3025 - 3031
(2019/08/30)
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- Straightforward chemo- and stereoselective fluorocyclopropanation of allylic alcohols: Exploiting the electrophilic nature of the not so elusive fluoroiodomethyllithium
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An unprecedented direct fluorocyclopropanation of allylic alcohols is reported. This simple method involves the not so elusive fluoroiodomethyllithium, a carbenoidic intermediate that under the developed conditions discloses its electrophilic nature. Gratifyingly, the reaction turned out to be highly chemo- and stereoselective, and DFT calculations provided insights into the structure and nature of this new type of carbenoid.
- Colella, Marco,Tota, Arianna,Gro?johann, Angela,Carlucci, Claudia,Aramini, Andrea,Sheikh, Nadeem S.,Degennaro, Leonardo,Luisi, Renzo
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supporting information
p. 8430 - 8433
(2019/07/22)
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- Synthesis of α,β-unsaturated aldehydes as potential substrates for bacterial luciferases
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Bacterial luciferase catalyzes the monooxygenation of long-chain aldehydes such as tetradecanal to the corresponding acid accompanied by light emission with a maximum at 490?nm. In this study even numbered aldehydes with eight, ten, twelve and fourteen carbon atoms were compared with analogs having a double bond at the α,β-position. These α,β-unsaturated aldehydes were synthesized in three steps and were examined as potential substrates in vitro. The luciferase of Photobacterium leiognathi was found to convert these analogs and showed a reduced but significant bioluminescence activity compared to tetradecanal. This study showed the trend that aldehydes, both saturated and unsaturated, with longer chain lengths had higher activity in terms of bioluminescence than shorter chain lengths. The maximal light intensity of (E)-tetradec-2-enal was approximately half with luciferase of P. leiognathi, compared to tetradecanal. Luciferases of Vibrio harveyi and Aliivibrio fisheri accepted these newly synthesized substrates but light emission dropped drastically compared to saturated aldehydes. The onset and the decay rate of bioluminescence were much slower, when using unsaturated substrates, indicating a kinetic effect. As a result the duration of the light emission is doubled. These results suggest that the substrate scope of bacterial luciferases is broader than previously reported.
- Brodl, Eveline,Ivkovic, Jakov,Tabib, Chaitanya R.,Breinbauer, Rolf,Macheroux, Peter
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p. 1487 - 1495
(2017/02/18)
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- Total synthesis and in vitro bioevaluation of clavaminols A, C, H & deacetyl clavaminol H as potential chemotherapeutic and antibiofilm agents
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A highly concise and expedient total synthesis of bioactive clavaminols (1-4) has been executed using commercially available achiral compound decanol. The synthetic strategy relied on trans-Wittig olefination, Sharpless asymmetric epoxidation, regioselective azidolysis and in situ detosylation followed by reduction as key reactions with good overall yield. Based on biological evaluation studies of all the synthesized compounds, it was observed that the clavaminol A (1) exhibited good cytotoxicity against DU145 and SKOV3 cell lines with IC50 value of 10.8 and 12.5 μM, respectively. Clavaminol A (1) and deacetyl clavaminol H (3) displayed selective promising inhibition towards Gram-positive pathogenic bacterial strains and showed good antifungal activity against the tested Candida strains. In addition, compounds 1 and 3 have demonstrated significant bactericidal activity. Compound 3 was found to be equipotent to the standard drug Miconazole displaying MFC value of 15.6 μg/mL against Candida albicans MTCC 854, C. albicans MTCC 1637, C. albicans MTCC 3958 and Candida glabrata MTCC 3019. Compounds 1 and 3 were also able to inhibit the biofilm formation of Micrococcus luteus MTCC 2470 and Staphylococcus aureus MLS16 MTCC 2940. Clavaminol A (1) increased the levels of reactive oxygen species (ROS) accumulation in M. luteus MTCC 2470.
- Vijai Kumar Reddy,Jyotsna,Prabhavathi Devi,Prasad,Poornachandra,Ganesh Kumar
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- Photoredox Activation of SF6for Fluorination
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We report the first practical use of SF6as a fluorinating reagent in organic synthesis. Photoredox catalysis enables the in situ conversion of SF6, an inert gas, into an active fluorinating species by using visible light. Under these conditions, deoxyfluorination of allylic alcohols is effected with high chemoselectivity and is tolerant of a wide range of functional groups. Application of the methodology in a continuous-flow setup achieves comparable yields to those obtained with a batch setup, while providing drastically increased material throughput of valuable allylic fluoride products.
- McTeague, T. Andrew,Jamison, Timothy F.
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p. 15072 - 15075
(2016/11/25)
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- Total synthesis and antifungal activity of (2S,3R)-2-aminododecan-3-ol
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We report the total synthesis of (2S,3R)-2-aminododecan-3-ol has been achieved starting from commercially available 10-undecenoic acid. The key steps involved are Sharpless asymmetric epoxidation, Miyashita's boron-directed C-2 regioselective azidolysis, generated the asymmetric centers and in situ detosylation and reduction of azido tosylate. The antifungal activity of the synthesized (2S,3R)-2-aminododecan-3-ol was evaluated on several Candida strains and was comparable to miconazole, a standard drug.
- Vijai Kumar Reddy,Prabhavathi Devi,Prasad,Poornima,Ganesh Kumar
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p. 4678 - 4680
(2012/08/07)
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- Structure-Activity relationship of aliphatic compounds for nematicidal activity against pine wood nematode (Bursaphelenchus xylophilus)
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Nematicidal activity of aliphatic compounds was tested to determine a structure-activity relationship. There was a significant difference in nematicidal activity among functional groups. In a test with alkanols and 2E-alkenols, compounds with C8-C11 chain length showed 100% nematicidal activity against pine wood nematode, Bursaphelenchus xylophilus, at 0.5 mg/mL concentration. C6-C10 2E-alkenals exhibited >95% nematicidal activity, but the other compounds with C 11-C14 chain length showed weak activity. Nematicidal activity of alkyl acetates with C7-C11 chain length was strong. Compounds belonging to hydrocarbons, alkanals, and alkanoic acetates showed weak activity at 0.5 mg/mL concentration. Nematicidal activity of active compounds was determined at lower concentrations. At 0.25 mg/mL concentration, whole compounds except C8 alkanol, C8 2E-alkenol, and C7 alkanoic acid showed >80% nematicidal activity. C 9-C11 alkanols, C10-C11 2E-alkenols, C8-C9 2E-alkenals, and C9-C10 alkanoic acids showed >80% nematicidal activity at 0.125 mg/mL concentration. Only C11 alkanol exhibited strong nematicidal activity at 0.0625 mg/mL concentration, the lowest concentration that was tested. 2010 American Chemical Society.
- Seo, Seon-M.I.,Junheon, Kim,Eunae, Kim,Park, Hye-M.I.,Kim, Young-Joon,Park, I.L.-Kwon
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experimental part
p. 1823 - 1827
(2010/09/09)
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- The reactivity of epoxides with lithium 2,2,6,6-tetramethylpiperidide in combination with organolithiums or grignard reagents
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(Chemical Equation Presented) The scope and limitations of lithium 2,2,6,6-tetramethylpiperidide (LTMP)-modified reductive alkylation of epoxides is detailed. A variety of organolithiums are added to terminal and 2,2-disubstituted epoxides in the presence of LTMP to generate alkenes in a completely regio- and highly stereoselective manner. Arylated alkenes, dienes, allylsilanes, and enynes are accessed using this procedure. The methodology is applied in the synthesis of the roller leaf moth pheromone, (3E,5Z)-dodecadienyl acetate. The corresponding reaction without LTMP has also been examined, and a study using deuterated epoxides provides insight into the mechanism. In the presence of LTMP, Grignard reagents are also shown to produce E-alkenes directly from epoxides.
- Hodgson, David M.,Fleming, Matthew J.,Stanway, Steven J.
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p. 4763 - 4773
(2008/02/04)
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- Asymmetric dihydroxylation and one-pot epoxidation routes to (+)- and (-)-posticlure: A novel trans-epoxide as a sex pheromone component of Orgyia postica (Walker)
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A highly enantioselective synthesis of (+)- and (-)-posticlure has been achieved. The synthesis features the Sharpless asymmetric dihydroxylation and one-pot epoxidation as the key steps.
- Fernandes, Rodney A,Kumar, Pradeep
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p. 6685 - 6690
(2007/10/03)
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- Posticlure: A novel trans-epoxide as a sex pheromone component of the tussock moth, Orgyia postica (Walker)
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A single EAG-active component was found in a pheromone extract from virgin females of the tussock moth, Orgyia postica. This compound named posticlure possesses a trans-epoxy ring and was identified as (6Z,9Z,11S,12S)-11,12-epoxyhenicosa-6,9-diene by means of GC-MS, 1H NMR and chiral HPLC analyses, and further chemical derivation followed by the GC-MS analysis. In a field test with the pheromone synthesized stereoselectivity, the male moths were specifically attracted to the (11S,12S)-isomer but not to the antipode.
- Wakamura, Sadao,Arakaki, Norio,Yamamoto, Masanobu,Hiradate, Syuntaro,Yasui, Hiroe,Yasuda, Tetsuya,Ando, Tetsu
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p. 687 - 689
(2007/10/03)
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- A simple synthetic method for chiral 1,2-epoxides and the total synthesis of a chiral pheromone epoxide
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Chiral 1,2-epoxyalkan-3-ol tosyl esters 4a-h were successfully synthesized from alkynols or allyl chlorides in three steps using Sharpless AD reaction as a key step in good yields. The chiral insect pheromone epoxide (6Z,9S,10R)-9,10-epoxyhenicos-6-ene 9 was thus smoothly synthesized from the corresponding key intermediate 4g.
- Zhang, Zhi-Bo,Wang, Zhi-Min,Wang, Yu-Xiu,Liu, Huan-Quan,Lei, Gui-Xin,Shi, Min
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- Fleming-Tamao oxidation and masked hydroxyl functionality: Total synthesis of (+)-pramanicin and structural elucidation of the antifungal natural product (-)-pramanicin
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The total synthesis of (+)-pramanicin (41b) is reported, thereby establishing the relative and absolute stereochemistry of the naturally occurring antifungal agent. The key steps involve (i) conjugate addition of the diethyl((diethylamino)diphenylsilyl)zincate to a suitably protected γ- lactam 3 and quenching of the resultant enolate with the α,β-unsaturated γ,δ-epoxy aldehyde 2 (X = H), (ii) Ni(acac)2-catalyzed hydroxylation of a β-dicarbonyl array, and (iii) Fleming-Tamao oxidation to reveal the masked C-3 hydroxyl group.
- Barrett, Anthony G. M.,Head, John,Smith, Marie L.,Stock, Nicholas S.,White,Williams
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p. 6005 - 6018
(2007/10/03)
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- A facile synthetic method for chiral 1,2-epoxides and the total synthesis of chiral pheromone epoxides
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Chiral 1,2-epoxy-3-alkanol tosylates were successfully synthesized from alkynols in three steps using the Sharpless AD reaction as a key step in good yields. Two chiral insect pheromone epoxides were smoothly obtained from the corresponding key intermediate.
- Zhang, Zhi-Bo,Wang, Zhi-Min,Wang, Yu-Xiu,Liu, Huan-Quan,Lei, Gui-Xin,Shi, Min
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p. 837 - 840
(2007/10/03)
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- Conformational mobility and preferences of Allyl-type organometallic intermediates : Dodec-2-eny lpotassium
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Alk-2-enylpotassium compounds having the endo conformation are synthetically very valuable precursors of (Z)-olefinic derivatives substituted at the outward allylic position. They may be generated by "stereoconservative" metalation of the readily available (Z)-alk-2-enes by using the superbasic mixture of butyllithium and potassium terf-butoxide or by metalation under similar conditions of stereorandom mixtures of alk-2-enes or alk-1-enes followed by torsional isomerization of the concomitantly formed exo conformers to the thermodynamically more stable endo species. The principal factors that dictate the rate and the extent of the endo/exo equilibration are the substrate geometry, the solvent, the temperature, the reagent stoichiometry, and catalysis Keywords: Torsional (ZIE) isomerization / Selectivity, regio- and stereo- / Allylsilanes / Allylic oxidation VCH Verlagsgescllschaft mbH.
- Franzini, Livia,Moret, Etienne,Schlosser, Manfred
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- 2,3-EPOXY DERIVATIVES AS ANTI RETROVITAL CHEMOTHERAPEUTIC AGENTS
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The present invention is related to compounds, compositions and methods of treating viral infections. Compounds of the present invention have the following general formula: STR1 wherein R is selected from--CH 2 OH,--CO 2 R 2,--CONR 3 R 4, or COR 5, wherein R 2 is hydrogen or a lower alkyl group, R 3 and R 4 are each independently hydrogen or a lower alkyl group, R 5 is an amino acid residue bound via a terminal nitrogen or peptide having at least two amino acid residues; and wherein R 1 is C 5-C 13 alkyl, aryl, aralkyl, aralkyl(lower alkyl) ether, or C 5-C. sub.13 alkyl (lower alkyl)ether.
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- Synthesis of the optical antipodes of 4-alkyl-γ-lactones
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Optical antipodes of 4-alkyl-γ-lactones 3 have been prepared by photochemical rearrangement of optically active α,β-epoxy diazomethyl ketones 1 in ethanol to give 4-hydroxy-alkenoates 2, followed by reduction of the alkene bond and subsequent lactonization.The required epoxy diazomethyl ketones 1 were obtained via the following sequence of reactions: alkylation of 2-propyn-1-ol, subsequent reduction to the alkenols 6, Sharpless epoxidation to 2,3-epoxy alcohols 7, oxidation to glycidic esters 8 and finally conversion to diazo ketones 1.The enantiomeric purities range from 84 to 100percent.
- Thijs, Lambertus,Waanders, Peter P.,Stokkingreef, Edwin H. M.,Zwanenburg, Binne
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p. 332 - 337
(2007/10/02)
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- PALLADIUM CATALIZED OXIDATION OF ALLYLSILANES WITH U.V. LIGHT AND MOLECULAR OXIGEN
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Photolysis of oxygenated acetone solutions of allylsilanes containing small amounts of palladium led to α,β-ethylenic alcohols, aldehydes or ketones.Efficient regiospecific oxidation can be observed when the allylsilane was substituted by an arylsulphonyl group.
- Riahi, A.,Cossy, J.,Muzart, J.,Pete, J. P.
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p. 839 - 842
(2007/10/02)
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- Synthesis of 4,5,8-Eicosatrienoic Acids
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The synthesis of (7(tert-butyldimethylsiloxy)hepta-3,4-dien-1-yl)triphenylphosphonium iodide (1) is described.The ylide derived from 1 undergoes highly stereoselective Wittig reactions with aliphatic aldehydes to give a series of (7Z)-nonadeca-3,4,7-trien-1-ols (4) which were transformed into arachidonic acid analogues including (8Z,11Z,14Z)-eicosa-4,5,8,11,14-pentaenoic acid (9).
- Patterson, John W.,Pfister, Jurg R.,Wagner, Paul J.,Murthy, D. V. Krishna
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p. 2572 - 2576
(2007/10/02)
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