The invention relates to a process for the preparation of 5-(1-hydroxy-2-urethanethylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione derivatives, which are precursors of chiral tetramic acid derivatives. According to this process, an N-urethane-protected .alpha.-amino acid N-carboxy-anhydride is reacted with Meldrum's acid in an inert organic solvent medium in the presence of a tertiary amine. This process makes it possible to conserve the chirality of the starting material and in particular to simplify the synthesis of 4-amino-3-hydroxy acids and the derivatives thereof via the tetramic acid route.
本发明涉及一种制备5-(1-羟基-2-
脲乙基亚甲基)-2,2-二甲基-1,3-二氧杂环戊-4,6-二酮衍
生物的方法,该衍
生物是手性四元酸衍
生物的前体。根据该方法,在惰性有机溶剂介质中,在三级胺的存在下,将N-
脲保护的
α-氨基酸N-
羧酸酐与梅尔德鲁姆酸反应。该方法使得起始物的手性得以保留,特别是通过四元酸途径简化合成4-
氨基-3-羟基酸及其衍
生物的方法。