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Asymmetric 1,4-addition of oxazolones to nitroalkenes by bifunctional cinchona alkaloid thiourea organocatalysts: synthesis of alpha,alpha-disubstituted alpha-amino acids



Asymmetric 1,4-addition of oxazolones to nitroalkenes by bifunctional cinchona alkaloid thiourea organocatalysts: synthesis of alpha,alpha-disubstituted alpha-amino acids



Chemistry 14(35): 10958-10966



An easy and simple synthetic approach to optically active alpha,alpha-quaternary alpha-amino acids using asymmetric organocatalysis is presented. The addition of oxazolones to nitroalkenes catalyzed by thiourea cinchona derivatives provides the corresponding alpha,alpha-quaternary alpha-amino acid derivatives with good yields, excellent diastereoselectivities (up to 98 % dr), and from moderate to good enantioselectivities (up to 92 % ee). The reaction can be performed on a large scale. The optically active oxazolone-nitroalkene addition products can be opened in a one-pot reaction to the corresponding ester-amide derivatives. Additional transformations are also presented, such as the synthesis of amino esters, amino acids, and transformation into 3,4-disubstituted pyrrolidin-2-ones.

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Accession: 051695554

Download citation: RISBibTeXText

PMID: 18979472

DOI: 10.1002/chem.200802030


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