高等学校化学学报

高等学校化学学报 ›› 1998, Vol. 19 ›› Issue (S1): 23.

• Plenary, Keynote and Invited Lectures • 上一篇    下一篇

C2, Symmetric Dibenzosuberanes as Templates for the Chirality Determination of Helicenes and Their Applications as Optically Switchable Memory Device

Y. C. Chou, J. I. Gao, C. T. Chen   

  1. Department of Chemistry, National Taiwan Normal University, #88, Sec. 4, Ding-Jou Road, Taipei, Taiwan
  • 出版日期:1998-12-31 发布日期:1998-12-31

C2, Symmetric Dibenzosuberanes as Templates for the Chirality Determination of Helicenes and Their Applications as Optically Switchable Memory Device

Y. C. Chou, J. I. Gao, C. T. Chen   

  1. Department of Chemistry, National Taiwan Normal University, #88, Sec. 4, Ding-Jou Road, Taipei, Taiwan
  • Online:1998-12-31 Published:1998-12-31

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摘要： We have recently developed a new type of chiral templates, dibenzosuberanes. Thess C2, symmetric diaryl modifiers have been successfully applied to the synthesis of chiral triarylcarbenium ions. They can serve as catalysts in the asymmetric Mukaiyama aldol reactions with moderate enantioselectivities of up to 50% [1]. We have subsequently found that one major side reaction between the catalyst and the substrate-silyl ketene acetal which releases extra silyl-X species is responsible for the erosion of asymmetric induction. The dibenzosuberane scaffold was found essential to prevent this type of side reaction. For the selection of carbenium counter ions, we have resorted to the chloride in order to completely suppress the undesired silyl catalysis [2].

Abstract: We have recently developed a new type of chiral templates, dibenzosuberanes. Thess C2, symmetric diaryl modifiers have been successfully applied to the synthesis of chiral triarylcarbenium ions. They can serve as catalysts in the asymmetric Mukaiyama aldol reactions with moderate enantioselectivities of up to 50% [1]. We have subsequently found that one major side reaction between the catalyst and the substrate-silyl ketene acetal which releases extra silyl-X species is responsible for the erosion of asymmetric induction. The dibenzosuberane scaffold was found essential to prevent this type of side reaction. For the selection of carbenium counter ions, we have resorted to the chloride in order to completely suppress the undesired silyl catalysis [2].

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