Stereochemistry of the so-obtained cage-shaped bis-β-lactams was assigned by X-ray diffraction analysis. Concerning the mechanism of formation of such hitherto unknown molecules, dimerization of an azetinone anion intermediate stereoselectively induced by Li+ chelation is suggested.
3-Arylisoxazoles与受阻的
锂酰胺反应生成顺式2,6-二芳基-3,7-二氮杂
三环[4.2.0.0 2,5 ] octan -4,8-二酮,收率良好。通过X射线衍射分析确定所获得的笼状双β-内酰胺的立体
化学。关于这种迄今未知分子的形成机理,提出了由Li +螯合立体诱导的氮杂
环丁烷酮阴离子中间体的二聚化。