• Title/Summary/Keyword: Asymmetric epoxidation

Search Result 9, Processing Time 0.017 seconds

Design and Synthesis of Binaphthol-Derived Chiral Ketone Catalysts for Dioxirane-Mediated Asymmetric Epoxidation of Olefins

  • 김양희;이교철;최대윤;이상기;송충의
    • Bulletin of the Korean Chemical Society
    • /
    • v.20 no.7
    • /
    • pp.831-834
    • /
    • 1999
  • Binaphthol-derived chiral ketones 1a-c were synthesized and were shown to serve as active catalysts for asymmetric epoxidation of olefins using Oxone, although their enantioselectivities were not high. However, very interestingly, the stereochemical outcome of the resulting epoxides implicates that in the epoxidation using 1a-c, the planar transition state may be more favorable than the spiro transition state.

Selective Epoxidation and Reduction of Rigid Cyclic ${\alpha},{\beta}$-Unsaturated Carbonyl Compounds (환상 ${\alpha},{\beta}$-불포화 카르보닐 화합물의 선택적 에폭시화 및 환원)

  • Ma, Eun-Sook
    • YAKHAK HOEJI
    • /
    • v.49 no.6
    • /
    • pp.443-448
    • /
    • 2005
  • Diosgenin (25 (R) - spirost-5-en-3$\beta$ -ol) was oxidized with 2,3-dichloro -5,6-dicyano-1,4-benzoquinone to form 25(R)-1,4,6-spirostatrien-3-one (1) as rigid cyclic $\alpha$,$\beta$-unsaturated carbonyl compound. This compound was reacted with $H_{2}O_{2}$, m-chloroperoxybenzoic acid (mCPBA), NaOCl in the presence with (R,R)- or (S,S)-Jacobsen catalyst, tert-butyl-hydroperoxide (TBHP) in Mo$(CO)_{6}$, and in VO $(acac)_{2}$ catalyst, respectively, 25(R) -1,4,6-spirostatrien -3-one (1) was reduced with $NaBH_{4}$ L-Selectride, $LiAIH_{4}$,$BH_{3}$ $\cdot$$(CH_{3})_{2}S$, Superhydride, Red-Al, and lithium tri-tert-butoxyaluminium hydride. And 25(R)-4,6-spirostadien-3$\beta$-ol (4) was treated with $H_{2}O_{2}$, mCPBA, TBHP in D - (-) - and L-(+)-diisopropyltar-trate and $Ti(OiPr)_{4}$ condition (Sharpless asymmetric epoxidation), TBHP in $Mo(CO)_{6}$, and in $VO(acac)_{2}$ catalyst, respectively.

Biocatalysis and Biotransformation for the Production of Chiral Epoxides (바이오촉매 및 생물전환을 이용한 광학활성 에폭사이드 제조)

  • Kim, Hee-Sook;Lee, Ok-Kyung;Lee, Eun-Yeol
    • Journal of Life Science
    • /
    • v.15 no.5 s.72
    • /
    • pp.772-778
    • /
    • 2005
  • Chiral epoxides are important chiral synthons in organic synthesis for the production of chiral pharmaceuticals and functional food additives. Chiral epoxides can be synthesized by enantioselective introduction of oxygen to double bond of substrate by monooxygenase. Peroxidase also carry out asymmetric epoxidation of alkene in the presence of hydrogen peroxide. Kinetic resolution of racemic epoxides via enantioselective hydrolysis reaction by epoxide hydrolase (EH) is a very promising method since chiral epoxides with a high optical purity can be obtained from cheap and readily available racemic epoxides. In this review, various biocatalytic approaches for the production of chiral epoxides with several examples are presented and their commercial potential is discussed.