Asymmetric Epoxidation of Terminal Olefins with Binaphthyl Strapped Porphyrin Catalysts: (-( Stacking Interaction and Steric Effects on the Enantioselectivities

Two binaphthyl strapped porphyrins with similar chiral auxiliaries 1b and 2b were used as efficient catalysts for asymmetric epoxidation of both styrene derivatives and non‐aromatic olefin substrates. Theoretical calculation of styrene approach to both catalysts has been performed. The subtle differ...

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Bibliographic Details
Published in:Chinese journal of chemistry 2009-05, Vol.27 (5), p.895-899
Main Authors: REN, Qizhi, WANG, Aiqing, LIU, Shuangyan, DING, Xiaojian
Format: Article
Language:English
Subjects:
asymmetric epoxidation
chiral porphyrin
enantioselectivity
π-π stacking interaction
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Summary:Two binaphthyl strapped porphyrins with similar chiral auxiliaries 1b and 2b were used as efficient catalysts for asymmetric epoxidation of both styrene derivatives and non‐aromatic olefin substrates. Theoretical calculation of styrene approach to both catalysts has been performed. The subtle difference of the chiral cavities between two porphyrins has been analyzed by 1H NMR. The π‐π stacking interaction between aromatic substrates and catalysts might be one factor for the dramatic different enantioselectivities. Besides, the steric effect of the binaphthyl handle of 1b and 2b also causes the high ee values for non‐aromatic olefin epoxidations. For efficient asymmetric epoxidation of styrene derivatives catalyzed by two porphyrins with similar chiral auxiliaries, the steric effect of the binaphthyl handle and the π‐π stacking interaction between substrates and catalysts might be two factors for the dramatic reversed enantioselectivities.
ISSN:1001-604X
1614-7065
DOI:10.1002/cjoc.200990151