Stereoselective dimerization of 3-arylisoxazoles to cage-shaped bis-β-lactams syn 2,6-diaryl-3,7-diazatricyclo[4.2.0.02,5]octan-4,8-diones induced by hindered lithium amides
作者:Leonardo Di Nunno、Paola Vitale、Antonio Scilimati、Laura Simone、Francesco Capitelli
DOI:10.1016/j.tet.2007.09.040
日期:2007.12
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。