The cover picture displays a class of novel isosteroidal alkaloids isolated from Fritillaria verticillata Willd. Among them, compounds 1—3 were unprecedented cis-fused D/E (13α,17α) cevanine alkaloids; compound 6 was one rarely cis-fused E/F (22α) cevanine alkaloid. Their structures were determined by the solid data acquired from diverse methods. In addition, some proton and carbon signals α to nitrogen in 6 and 7 are unobservable due to the ¹⁴N nuclear quadrupolar relaxation, based on the NMR experiments in different solvents, calculated NMR method and X-ray technology, their structures were determined. The NMR characteristics of cevanine alkaloids to distinguish orientation of long-pair on nitrogen atom with β-hydroxyl at C-20 were also concluded. More details are discussed in the article by Pei et al. on page 1945–1956.

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内封底

封面图片展示了从贝母中分离出的一类新型异甾体生物碱。其中，化合物1-3是前所未有的顺式融合D/E(13α,17α)鬼臼碱生物碱；化合物 6 是一种很少顺式融合的 E/F (22α) cevanine 生物碱。它们的结构是由从各种方法获得的可靠数据确定的。此外，由于¹⁴N核四极弛豫，基于不同溶剂中的核磁共振实验，计算核磁共振方法和X射线技术，确定了它们的结构。还总结了cevanine生物碱的NMR特征，以区分氮原子上的长对与C-20处的β-羟基的取向。Pei 等人的文章中讨论了更多细节。1945-1956 页。