Enantioselective epoxidation of 2-substituted 1,4-naphthoquinones using gem-dihydroperoxides
摘要:
New gem-dihydroperoxides were successfully used for DBU-promoted enantioselective epoxidation of 2-substituted 1,4-naphtlloquinones. The corresponding 1,4-naphthoquinone epoxides were obtained in yields up to 97% and ee's up to 82%. (C) 2009 Elsevier Ltd. All rights reserved.
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