The base n-BuLi with sparteine allows a kinetic resolution of N-Boc-2-aryl-4-methylenepiperidines. The 2,2-disubstituted products and recovered starting materials were isolated with high enantiomeric ratios. From VT-NMR spectroscopy and DFT studies, the rate of rotation of the N-Boc group is fast. Lithiation and trapping of the enantioenriched starting materials gave 2,2-disubstituted piperidines with retention of stereochemistry. Functionalization of the 4-methylene group led to a variety of 2,4-disubstituted piperidines without loss of enantiopurity that could be useful building blocks for drug discovery.

中文翻译：

---

2-芳基-4-亚甲基哌啶对对映体富集功能化哌啶片段的动力学拆分

碱基n - BuLi 与 sparteine 可实现N -Boc -2-aryl-4-methylenepiperidines 的动力学拆分。以高对映体比率分离 2,2-二取代产物和回收的起始材料。根据 VT-NMR 光谱和 DFT 研究， N -Boc 基团的旋转速率很快。对映体富集的起始材料的锂化和捕获得到具有立体化学保留的 2,2-二取代哌啶。4-亚甲基的官能化产生了多种 2,4-二取代哌啶，而不会损失对映纯度，这可能是药物发现的有用构件。