作者:Roger R. Hill、David Birch、Graham E. Jeffs、Michael North
DOI:10.1039/b211914e
日期:2003.3.13
Selectivity in abiotic condensations of amino acids remains controversial and stereochemically little explored. We find that competitive activated couplings of N-acyl derivatives of glycine, alanine, valine, proline and phenylalanine with binary, ternary and quaternary mixtures of amides and esters of the same group of amino acids show little selectivity among the reactants, except with respect to configuration, where a consistent and significant preference for heterochiral outcomes, mostly >80%, is observed. One possible explanation of this selectivity predicts a predisposition to homochiral coupling under conditions that would require the two carboxyl functions to be co-facial in the activated complex.
无机物促成的氨基酸缩聚反应中选择性仍然备受争议,而立体化学方面的研究甚少。我们发现,以酰胺和酯组成的双组分、三组分以及四组分混合物为底物,对甘氨酸、丙氨酸、缬氨酸、脯氨酸和苯丙氨酸的N-酰基衍生物进行竞争性活化偶联的反应中,产物在底物分子层面选择性较低,但对映异构选择性较高,选择性系数大多大于80%。此类反应中优先生成异手性产物的一种可能的解释是,在两个羧基必须共面的活化复合物中,同手性偶联具有倾向性。