New asymmetric catalysis by (salen)cobalt(III) complexes (salen = [bis(salicylidene)ethylenediaminato] = {{2,2′-[ethane-1,2-diyl]bis[(nitrilo-κN) methylidyne]bis[phenolato-κO]}(2-)}) of cis-β-structure: Enantioselective Baeyer-Villiger oxidation of prochiral cyclobutanones

Tatsuya Uchida, Tsutomu Katsuki, Katsuji Ito, Suemi Akashi, Ayako Ishii, Tomomi Kuroda

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Abstract

A series of chiral (salen)cobalt(III) complexes (salen=[bis(salicylidene)ethylenediaminato]={{2,2'-[(ethane-1, 2-diyl)bis[(nitrilo-κN)methylidyne]bis[phenolato-κ0]}(2-)}) of cis-β structure were prepared and used for the enantioselective Baeyer-Villiger oxidation of prochiral cyclobutanones with hydrogen peroxide as terminal oxidant. Both cationic (salen)cobalt(III) and neutral iodo(salen)cobalt(III) complexes 3-5 and 7-12, respectively, all having a chiral binaphthalenediamine unit, were found to be effective catalysts for the enantioselective Baeyer-Villiger oxidation (Tables 1, 3, and 4). In particular, complex 8 bearing electron-withdrawing F-atoms showed a good level of enantioselectivity (75-79% ee) in the reactions of 3-arylcyclobutanones (Scheme 4). On the other hand, complex 12 bearing 'Bu groups at C(3) and C(3') and electron-withdrawing NO2 groups at C(5) and C(5') (trivial numbering) exhibited a high enantioselectivity of 98% ee in the reaction of a tricyclic cyclobutanone (Table 4).

Original languageEnglish
Pages (from-to)3078-3089
Number of pages12
JournalHelvetica Chimica Acta
Volume85
Issue number10
DOIs
Publication statusPublished - Nov 26 2002

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All Science Journal Classification (ASJC) codes

  • Catalysis
  • Biochemistry
  • Drug Discovery
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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