intramolecular opening of the 1-Boc-β-lactam, initiated by 7-exotrig ring closure from the NH2 of the Orn side chain. The synthetic route is applied to the stereoselective preparation of enantiomerically pure 4-amino-3-methyl-2-oxoazepane-4-carboxylate derivatives, for which the structure and configuration is confirmed by X-ray diffraction. Molecular modeling and NMR experiments indicate that these quaternary
为了进一步探索
氨基酸衍生的β-内酰胺的
化学性质,研究了它们向α,α-杂环季
氨基酸衍
生物的转化。后者的衍
生物含有2-氧杂氮杂
环庚烷作为α,α-取代基,是通过简单的Pd-C催化的Orn(Z)衍生的2-氮杂
环丁烷酮的氢解反应合成的。1-元-β-内酰胺的关键分子内开环驱动四元至七元内酰胺环的重排,该开环由NH 2的7-外环封闭而引发Orn侧链。该合成路线适用于对映体纯的4-
氨基-3-甲基-2-氧杂氮杂
环庚烷-4-
羧酸酯衍
生物的立体选择性制备,其结构和构型通过X射线衍射确定。分子建模和NMR实验表明,当掺入模型二肽衍
生物中时,这些季
氨基酸能够驱动β-turn二级结构的采用。