Development of Dinuclear Vanadium Catalysts for Enantioselective Coupling of 2-Naphthols via a Dual Activation Mechanism
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- Takizawa Shinobu
- The Institute of Scientific and Industrial Research, Osaka University
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This review describes our recent efforts in the development of chiral dinuclear vanadium complexes which work as dual activation catalysts for oxidative coupling of 2-naphthols. A chiral dinuclear vanadium(IV) complex (Ra,S,S)-1a possessing (S)-tert-leucine moieties at the 3,3′-positions of the (R)-binaphthyl skeleton was developed, and found to promote oxidative coupling of 2-naphthol to afford (S)-1,1′-bi-2-naphthol (BINOL) with 91% ee. To verify the dual activation mechanism, mononuclear vanadium(IV) complex (S)-10 was also prepared. Kinetic analysis revealed that the reaction rate of oxidative coupling of 2-naphthol promoted by (Ra,S,S)-1a is 48.3 times faster than that of (S)-10. In the coupling reaction, the two vanadium metals in the chiral complex activate two molecules of 2-naphthol simultaneously achieving a high reaction rate with high enantiocontrol. Since the dinuclear vanadium(IV) complex was found to be readily oxidized to afford a corresponding vanadium(V) species during preparation in air, a new synthetic procedure using VOCl3 and a convenient one-pot procedure using VOSO4 under O2 have been applied towards dinuclear vanadium(V) complexes (Ra,S,S)-2. The coupling of 2-naphthol was catalyzed by (Ra,S,S)-2 with reaction rates enhanced 2.3 times faster than that of (Ra,S,S)-1a, which is likely a precatalyst. To the best of our knowledge, (Ra,S,S)-1a, 2, and 3 show considerably higher catalytic activity than previously reported vanadium complexes for oxidative coupling of 2-naphthols.
収録刊行物
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- CHEMICAL & PHARMACEUTICAL BULLETIN
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CHEMICAL & PHARMACEUTICAL BULLETIN 57 (11), 1179-1188, 2009
公益社団法人 日本薬学会
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詳細情報 詳細情報について
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- CRID
- 1390282679146133888
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- NII論文ID
- 130000124805
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- NII書誌ID
- AA00602100
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- ISSN
- 13475223
- 00092363
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- NDL書誌ID
- 10412358
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
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