- Enantioselective epoxidation of 2-substituted 1,4-naphthoquinones using gem-dihydroperoxides
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New gem-dihydroperoxides were successfully used for DBU-promoted enantioselective epoxidation of 2-substituted 1,4-naphthoquinones. The corresponding 1,4-naphthoquinone epoxides were obtained in yields up to 97% and ee's up to 82%.
- Bunge, Alexander,Hamann, Hans-Jürgen,McCalmont, Eve,Liebscher, Jürgen
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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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p. 2811 - 2815
(2018/05/29)
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