A novel approach for the synthesis of enamine derivatives of N-protected 3-acyltetramic acids is described. The synthetic procedure relies on α-C-acylation of β-enamino amides with N-protected α-amino acids and subsequent cyclisation of the obtained intermediates in refluxing TFA. The tetramic derivatives are obtained with very good enantiopurity (e.r. ≥95:5). Ring-enlarged analogues (piperidine-2,4-diones) can also be obtained from β-amino acids.

中文翻译：

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β-烯氨基酰胺和氨基酸中的3-酰基四酸的烯胺

描述了一种新的合成N-保护的3-酰基四酸的烯胺衍生物的方法。的合成方法依赖于α- Ç β-烯酰胺的酰化用ñ -保护所获得的中间体的α氨基酸和随后环在回流的TFA。获得具有良好对映体纯度（er≥95：5）的四级衍生物。环扩大的类似物（哌啶-2,4-二酮）也可以从β-氨基酸获得。