- Synthesis of α,β-Unsaturated Acylsilanes via Perrhenate-Catalyzed Meyer-Schuster Rearrangement of 1-Silylalkyn-3-ols
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We report the synthesis of α,β-unsaturated acylsilanes via the perrhenate-catalyzed Meyer-Schuster rearrangement of 1-silylalkyn-3-ols. Propargylic alcohols derived from TES-acetylene and substituted benzaldehydes can be converted to acylsilanes using a c
- Nikolaev, Andrei,Orellana, Arturo
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- Synthesis method of dienal or dienone compound
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The invention discloses a synthesis method of a dienal or dienone compound. The method comprises subjecting olefin aldehyde or ketene adopted as a starting raw material to one-step dehydrogenation ina polar organic solvent to obtain a (E,E)-dienal or (E,E)-dienone compound, by adopting a palladium compound as a catalyst, adopting oxygen as an oxidant and adopting trifluoroacetic acid as an additive. The method provided by the invention realizes synthesis of (E,E)-dienal and (E,E)-dienone compounds with single three-dimensional configuration through oxidative dehydrogenation catalyzed by a transition metal, and compared with traditional methods, the method has the advantages of cheap and easily available raw materials, simple operation, a wider substrate application range, higher reactionefficiency, environmental friendliness, a high yield and a high atom utilization rate.
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Paragraph 0013; 0014
(2019/12/02)
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- Total syntheses of the gregatins A-D and aspertetronin A: Structure revisions of these compounds and of aspertetronin B, together with plausible structure revisions of gregatin E, cyclogregatin, graminin A, the penicilliols A and B, and the huaspenones A and B
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Comprehensive comparisons of 1H and 13C NMR chemical shift values in the furanone cores a, b, and c provide plausible support for a reassessment of the furanone nuclei of the title compounds from b to c. Total syntheses via enantiomerically pure lactic esters were based on the Seebach-Frater "self-reproduction of stereocenters" methodology. Attachment of the hexadienyl side-chain in a trans,trans-selective manner was achieved by addition of the Seebach-Frater enolate to trans-hex-4-en-1-al rather than to trans-hex-3-en-1-al. The type-c furanone cores of the synthetic materials were reached by single or double acylation of a model γ-hydroxy-β-oxo ester (compound 50) and its hexadiene-containing counterpart 29. Our syntheses confirmed the novel connectivities in six compounds. In addition, they required revision of the configuration of a quaternary carbon atom in five cases. Moreover, they allowed elucidation of the configurations of four previously unassigned stereocenters. Hindsight analyses of why the furanone cores of the title compounds had been misinterpreted as a and/or b instead of c are given. Why the stereocenters in the heterocycles had been incorrectly configured, on the bases (a) of relay studies in the 1960s, and (b) of a 1984 total synthesis of gregatin B, is also discussed.
- Burghart-Stoll, Heike,Brueckner, Reinhard
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supporting information; experimental part
p. 3978 - 4017
(2012/10/18)
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- Palladium-catalyzed dienylations of chelated enolates
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Isomerization-free reactions of dienyl carbonates with chelated amino acid ester enolates at -78 °C provide important information concerning the mechanism of these dienylations. The formation of regioisomeric products can be explained by competing SN2/SN2′ reactions, and the product distribution can be influenced by the proper choice of the reaction conditions. Chiral allylic substrates show a significant transfer of chirality. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Basak, Sankar,Kazmaier, Uli
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supporting information; experimental part
p. 4169 - 4177
(2009/05/30)
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- Highly Stereoselective Isomerization of Ynones to Conjugated Dienones Catalyzed by Transition-Metal Complexes
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α,β-Ynones isomerize in the presence of a catalytic amount of IrH5(i-Pr3P)2, RuH2(Ph3P)4-Bu3P, or RuCl2(Ph3P)3-Ph3P in benzene at 35-80 deg C to give (E,E)-α,β:γ,δ-dienones in high yield with high stereoselectivity.This experimentally simple and economica
- Ma, Dawei,Yu, Yihua,Lu, Xiyan
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p. 1105 - 1109
(2007/10/02)
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- The Cycloaddition of the 1,3-Butadiene Radical Cation with Acrolein and Methyl Vinyl Ketone
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The 1,3-butadiene radical cation reacts with acrolein and methyl vinyl ketone to produce 'stable' adducts.The nature of the reaction and the structures of the adducts were investigated by collisional activation decomposition (CAD) combined with tandem mas
- Castle, Lyle W.,Gross, M. L.
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p. 637 - 646
(2007/10/02)
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- A NOVEL STEREOSELECTIVE SYNTHESIS OF CONJUGATED DIENONES
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(E,E)-α,β-γ,δ-Dienones are synthesized stereoselectively from the corresponding α,β-ynones in high yield under the catalysis of a ruthenium hydride complex.
- Ma, Dawei,Lin, Yingrui,Lu, Xiyan,Yu, Yihua
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p. 1045 - 1048
(2007/10/02)
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- Synthesis of Isoaspertetronin, Isogregatin and Related O-Methyltetronic Acids. Reassignment of 5-Methoxyfuran-3(2H)-one Structures to the Aspertetronin Group of Natural Products
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Reaction between (3E,5E)-octa-3,5-dien-2-one and the vinylic anion (10) derived from (9) leads, in one step, to the O-methyltetronic acid (12).The tetronate (12) was also obtained by treatment of the lithium anion derived from ethyl propiolate with the octadienone (11), followed by reaction of the resulting hydroxyester (17) with methanolic sodium methoxide.Metallation of the O-methyltetronic acid (12), followed by the tratment of the resulting C-2(α-)-vinylic anion (19) with methyl acetate and methyl (E)-butenoate then gave the acylated O-methyltetronic acids (20) and (22) respectively.The O-methyltetronic acids (20) and (22) are shown, by comparison of physical and spectroscopic data, to be enol ether isomers of the natural products gregatin B and aspertetronin A found in Aspergillus sp. and Cephalosporium gregatum.The aspertetronin (also known as gregatin and graminin) group of natural products are all shown to have the 5-methoxyfuran-3(2H)-one structure (25) rather than the previously assigned O-methyl tetronic acid structure e.g. (1).We propose the names isoaspertetronin and isogregatin B for the synthetic O-methyltetronic acids (22) and (20) respectively.
- Clemo, Nicholas G.,Pattenden, Gerald
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p. 2407 - 2412
(2007/10/02)
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