The invention provides novel compounds and methods to carry out organocatalytic Michael additions of aldehydes to nitroethylene catalyzed by a proline derivative to provide α-substituted-γ-nitroaldehydes. The reaction can be rendered enantioselective when a chiral pyrrolidine catalyst is used, allowing for Michael adducts in nearly optically pure form (e.g., 96-99% e.e.). The Michael adducts can bear a single substituent or dual substituents adjacent to the carbonyl. The Michael adducts can be efficiently converted to protected γ
2
-amino acids, which are essential for systematic conformational studies of γ-peptide foldamers.
Peptide Catalyzed Asymmetric Conjugate Addition Reactions of Aldehydes to Nitroethylene—A Convenient Entry into γ<sup>2</sup>-Amino Acids
作者:Markus Wiesner、Jefferson D. Revell、Sandro Tonazzi、Helma Wennemers
DOI:10.1021/ja801027s
日期:2008.4.1
The peptide H-D-Pro-Pro-Glu-NH2 is a highly effective catalyst for conjugateadditionreactions between aldehydes and nitroethylene. Only 1 mol % of H-d-Pro-Pro-Glu-NH2 and a 1.5-fold excess of aldehyde with respect to nitroethylene suffice to obtain gamma-nitroaldehydes and, after reduction, monosubstituted gamma-nitroalcohols in excellent yields and optical purities. The products can be readily converted
The invention provides novel compounds and methods to carry out organocatalytic Michael additions of aldehydes to nitroethylene catalyzed by a proline derivative to provide α-substituted-γ-nitroaldehydes. The reaction can be rendered enantioselective when a chiral pyrrolidine catalyst is used, allowing for Michael adducts in nearly optically pure form (e.g., 96-99% e.e.). The Michael adducts can bear a single substituent or dual substituents adjacent to the carbonyl. The Michael adducts can be efficiently converted to protected γ
2
-amino acids, which are essential for systematic conformational studies of γ-peptide foldamers.