Proline-Catalyzed Enantioselective Michael Additions of Ketones to Nitrostyrene

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

References

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1

On leave from the Department of Synthetic Chemistry, Faculty of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.

11

The reaction using (S)-proline in DMSO resulted in an enantiomeric excess of 7% ee and a yield of 97%. [7a]

12

The reaction in DMSO gave (S,R)-3f in high yield but low enantioselectivity by employing 15 mol% of (S)-proline. [7a]