Chemistry - A European Journal
10.1002/chem.201605610
COMMUNICATION
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pattern of Lewis acid catalysis (B) and the other in the form of
zinc enolate (A), respectively. In the stereoselectivity-
determining step, the LUMO-lowered cyano cation approaching
the enolate plane from Si face got the transition state (C)
arranged very effectively as a result of π-π interactions between
substrate and cyanate and the ligand.
2 2
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In summary, a highly enantioselective α-cyanation of cyclic
β-keto carbonyls has been developed using readily available 4-
acetylphenyl cyanate as the cationic cyano source for the first
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excellent yields and up to 97% ee under mild conditions. This α-
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2
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Keywords: asymmetric catalysis • cyanation • enantioselectivity
•
nitrile • Lewis acid
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