- Oxidative Alkoxycarbonylation of Alkynes by Means of Aryl α-Diimine Palladium(II) Complexes as Catalysts
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The straightforward in situ synthesized bis(2,6-diisopropyl)acenaphthenequinonediimine palladium triflate catalyst was generally employed for both the mono-alkoxycarbonylation of terminal alkynes, and the bis-alkoxycarbonylation of 1,2-disubstituted alkynes by using mild reaction conditions [carbon monoxide pressure (PCO)=4 bar, temperature=20 °C]. Utilizing low catalyst loading (down to 0.5 mol%), a variety of propiolic esters were synthesized with good to excellent isolated yields. Most importantly the system was very efficient not only with methanol but also with a range of different alcohols, starting from the less hindered benzyl alcohol to the most hindered ones, such as isopropyl alcohol and tert-butyl alcohol. In addition, aromatic and aliphatic 1,2-disubstituted alkynes were converted into maleic acid derivatives, together with an acid-catalyzed isomerization reaction, showing modest to good selectivity and excellent combined yields. In particular 3-hexyne showed a satisfactory degree of selectivity for the maleic diesters of methanol and benzyl alcohol, obtaining the corresponding products with good isolated yields. (Figure presented.).
- Beltrani, Michela,Carfagna, Carla,Milani, Barbara,Mancuso, Raffaella,Gabriele, Bartolo,Fini, Francesco
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p. 3244 - 3253
(2016/10/21)
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- Synthesis and rearrangement of dewar benzenes into biaryls: Experimental evidence for conrotatory ring opening
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Rearrangement of aryl-substituted Dewar benzenes into the corresponding biaryls may serve as an alternative pathway for synthesis of sterically hindered biaryls. The kinetic data obtained from thermal rearrangements of Dewar benzenes provide experimental
- Jankova, Stepanka,Dracinsky, Martin,Cisarova, Ivana,Kotora, Martin
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- Synthesis of sterically hindered biaryls by Zr-mediated Co-cyclotrimerization of alkynes
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Treatment of zirconacyclopentadienes with ortho-substituted arylpropynoates in the presence of stoichiometric amounts of CuCl or NiBr 2(PPh3)2 represents a novel approach to the synthesis of biaryls, formed in good yields. The CuCl-mediated reaction proceeded through two reaction mechanisms, also affording Dewar benzenes together with the corresponding biaryls Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Dufkova, Lenka,Kotora, Martin,Cisarova, Ivana
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p. 2491 - 2499
(2007/10/03)
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- Enantioselective synthesis of axially chiral phthalides through cationic [Rh1(H8-binap)]-catalyzed cross alkyne cyclotrimerization
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(Chemical equation presented). Easy access to axially chiral phthalides that bear one or two oxymethylene functionalities is provided by an enantioselective cross alkyne cyclotrimerization in the presence of the cationic complex [Rh1{(S)-H8-binap}]+. The axial chirality is introduced during the formation of the benzene ring with high enantioselectivity.
- Tanaka, Ken,Nishida, Goushi,Wada, Azusa,Noguchi, Keiichi
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p. 6510 - 6512
(2007/10/03)
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