摘要 : An easy and simple synthetic approach to optically active a,a-quaternary a-amino acids using asymmetric organocatalysis is presented. The addition of oxazolones to nitroalkenes catalyzed by thiourea cinchona derivatives provides t... 展开 An easy and simple synthetic approach to optically active a,a-quaternary a-amino acids using asymmetric organocatalysis is presented. The addition of oxazolones to nitroalkenes catalyzed by thiourea cinchona derivatives provides the corresponding a,a-quaternary a-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. 收起