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DOI: 10.1055/s-0028-1083574
A New Catalyst for the Desymmetrization of Cyclic Anhydrides
Rezensent(en):Benjamin List, Steffen MüllerUniversity of Toronto, Canada; Sungkyunkwan University, Suwon and AmorePacific Corporation, Yongin, Korea
A Highly Reactive and Enantioselective Bifunctional Organocatalyst for the Methanolytic Desymmetrization of Cyclic Anhydrides: Prevention of Catalyst Aggregation
Angew. Chem. Int. Ed. 2008, 47: 7872-7875
Publikationsverlauf
Publikationsdatum:
20. November 2008 (online)
Key words
cyclic anhydrides - desymmetrization - bifunctional catalysts - methanolysis
Significance
A new hydrogen-bonding cinchona alkaloid based organocatalyst was designed by focusing on the prevention of catalyst selfaggregation. Due to the lack of this deactivation mode, the resulting bifunctional chiral sulfonamide 1 showed unprecedented catalytic activity in the methanolytic desymmetrization of meso-anhydrides. The reaction proceeds at room temperature within few hours in excellent yields (88-97%) and enantioselectivities (er = 95.5:4.5 to 98.5:1.5).
Review: Y. Cheng, P. McDaid, L. Deng Chem. Rev. 2003, 103, 2965-2984.
Comment
The alcoholytic desymmetrization of meso-anhydrides with cinchona catalysts is a well established reaction in organocatalysis although turnover numbers are frequently moderate (see Review). Unfortunately, previously introduced hydrogen-bonding catalysts suffer from self-aggregation, coming along with lower reactivity and strongly temperature- and concentration-dependent enantioselectivities. Since 1 was especially designed to avoid this phenomenon, the catalyst showed an unprecedented reactivity beside excellent enantioselectivities. The application of 1 in other organocatalytic transformations seems promising.