- The Application of 2-Benzyl-1,4-naphthoquinones as Pronucleophiles in Aminocatalytic Synthesis of Tricyclic Derivatives
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This study demonstrates an unprecedented reactivity of 2-substituted-1,4-naphthoquinones. By applying the principle of vinylogy, they have been employed as vinylogous pronucleophiles in the organocatalytic cascade reaction for the first time. This novel catalytic activation of 1,4-naphthoquinones enables access to carboannulated naphthalen-1(4H)-one derivatives of biological importance. The site-selectivity and stereoselectivity of a process proved possible to control by the proper choice of reaction conditions.
- Skrzyńska, Anna,Romaniszyn, Marta,Pomiklo, Dominika,Albrecht, Lukasz
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p. 5019 - 5026
(2018/05/17)
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- Asymmetric Epoxidation of 1,4-Naphthoquinones Catalyzed by Guanidine-Urea Bifunctional Organocatalyst
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An enantioselective nucleophilic epoxidation of 2-substituted 1,4-naphthoquinones in the presence of a newly developed guanidine-bisurea bifunctional organocatalyst with tert-butyl hydroperoxide (TBHP) as an oxidant is presented. 1,4-Naphthoquinones bearing substituents at C6, C7, and C2 were available for the reaction, and the corresponding epoxides were obtained with 88:12-95:5 er in 71-98% yields. DFT calculations indicated that substituents at C2 and C6 in the terminal Ar group of the catalyst 9k play a key role in controlling the stereochemical outcome.
- Kawaguchi, Masaki,Nakano, Katsuhiro,Hosoya, Keisuke,Orihara, Tatsuya,Yamanaka, Masahiro,Odagi, Minami,Nagasawa, Kazuo
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supporting information
p. 2811 - 2815
(2018/05/29)
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- Electroorganic reactions. Part 56: Anodic oxidation of 2-methyl- and 2-benzylnaphthalenes: Factors influencing competing pathways
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A systematic investigation of the anodic oxidation in nucleophilic media of 2-methyl and 2-benzylnaphthalenes, substituted at the 6-position in the naphthalene nucleus and at the 4-phenyl position of the benzylic side chain, has been carried out to identify factors favouring side-chain substitution. Cyclic voltammetry confirms that 6-substitution has a profound effect on the oxidation potentials of the naphthalene nucleus and 13C chemical shifts indicate polar effects at the benzylic carbon. However, little side-chain anodic oxidation is observed under any conditions tried; the radical-cations of electron-rich substrates preferentially dimerise and a strongly electron-withdrawing substituent at the 6-position (EtOSO2) promotes nuclear substitution. In contrast, oxidation with DDQ in aqueous acetic acid gives efficient side-chain oxidation for electron rich substrates, consistent with hydride transfer, possibly intramolecularly via a charge transfer complex.
- Utley, James H.P,Rozenberg, Gregor G
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p. 5251 - 5265
(2007/10/03)
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