Abstract
Proline-catalyzed Michael additions of ketones to nitrostyrene were examined to obtain
optically active γ-nitro ketones. The catalytic asymmetric 1,4-additions afforded
the desired γ-nitro ketones in medium to excellent yields and up to 97% de of the syn-diastereomers and 76% ee.
Key words
asymmetric synthesis - asymmetric catalysis - Michael additions - nitro ketones -
nitroalkenes
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On leave from the Department of Synthetic Chemistry, Faculty of Engineering, Yokohama
National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
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The reaction using (S)-proline in DMSO resulted in an enantiomeric excess of 7% ee and a yield of 97%.
[7a]
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The reaction in DMSO gave (S,R)-3f in high yield but low enantioselectivity by employing 15 mol% of (S)-proline.
[7a]