Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Access Right: Open AccessAuthor: search.filters.author.Akpınar, Gürkan Eray

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  • Article
    Citation - WoS: 21
    Citation - Scopus: 21
    Regio- and Stereoselective Synthesis of 2,3,5-Trienoates by Palladium-Catalyzed Alkoxycarbonylation of Conjugated Enyne Carbonates
    (American Chemical Society, 2014) Karagöz, Ezgi Şule; Kuş, Melih; Akpınar, Gürkan Eray; Artok, Levent
    Palladium-catalyzed carbonylation of 2,4-enyne carbonates in an alcohol and under balloon pressure of CO proceeds through 1,5-substitution to yield (E)-2,3,5-trienoates. The olefin geometry of the substrate is important to control the overall stereochemistry of this alkoxycarbonylation method. The reaction proceeds through successive formation of π-allylpalladium with an R3 group oriented syn and σ-allenyl palladium complexes.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 15
    Rhodium- and Palladium-Catalyzed 1,5-Substitution Reactions of 2-En Acetates and Carbonates With Organoboronic Acids
    (American Chemical Society, 2011) Üçüncü, Muhammed; Karakuş, Erman; Kuş, Melih; Akpınar, Gürkan Eray; Aksın Artok, Özge; Krause, Norbert; Karaca, Sıla; Elmaci, Nuran; Artok, Levent
    Two methods involving the rhodium-catalyzed reaction of 2-en-4-yne acetates and the palladium-catalyzed reaction of 2-en-4-yne carbonates with organoboronic acids were investigated; both afforded exclusively the (E)-configured vinylallenes. The coordinative interaction of the rhodium with the acetate group promoted the δ-elimination of Rh(I)-OAc from the alkenylrhodium intermediate II in both syn and anti modes, with the syn-elimination being the major path. DFT calculations revealed that a conformer of this intermediate (II), which can lead to the (E)-configured vinylallene product via the syn-elimination mode, is energetically the most favorable conformer. The rhodium-catalyzed procedure is not applicable to reactions involving (E)-configured enyne acetates, because the geometry of the alkenylrhodium intermediate that is derived from the corresponding (E)-enyne acetate would not allow such coordinative interaction to occur. The palladium-catalyzed method, which proceeds through formation of the σ-vinylallenylpalladium intermediate, B, is suitable for both the (E)- and (Z)-configured enyne carbonates and appears to have a wider scope for both organoboronic acids and enyne substrates. The palladium-catalyzed reaction of an enantiomerically enriched enyne carbonate proceeded with racemization.