Chlorocyclopropanes (CCPs) conjugated to alk‐yn‐enes occur in a unique family of polyketide natural products from marine sponges. Synthesis of several optically enriched analogs of CCPs and measurement of their UV–vis spectra and electronic circular dichroism (ECD) spectra reveal unusually strong hyperconjugation that constrains and aligns the cyclopropyl C‐C bond with the π‐plane of the distal ene‐bond
与
炔烃共轭的
氯环丙烷(CCP)存在于海洋海绵的独特的聚酮化合物
天然产物家族中。几种CCP的光学富集类似物的合成以及它们的UV-vis光谱和电子圆二色性(
ECD)光谱的测量揭示了异常强的超共轭,该超共轭将环丙基C-C键约束并与远侧烯键的π平面对齐。该对准施加至少5.0kcal·mol -1的旋转障碍。手性CCP中红移棉效应的比较表明,该屏障独立于烯烃取代基,并为其他含CCP
天然产物的分配建立了经验规则。