Abstract：
Structural elucidation has always been challenging, and misassignment remains a stringent issue in the field of natural products. The growing interest in discovering unknown, complex natural structures accompanies the increasing awareness concerning misassignments in the community. The combination of various spectroscopic methods with molecular modeling has gained popularity in recent years. In this work, we demonstrated, for the first time, its power to fully elucidate the 2-dimensional and 3-dimensional structures of two epimers in an epimeric mixture of 6-hydroxyhippeastidine. DFT calculation of chemical shifts was first performed to assist the assignment of planar structures. Furthermore, relative and absolute configurations were established by three different ways of computer-assisted structure elucidation (CASE) coupled with ORD/ECD/VCD spectroscopies. In addition, the significant added value of OR/ORD computations to relative and absolute configuration determination was also revealed. Remarkably, the differentiation of two enantiomeric scaffolds (crinine and haemanthamine) was accomplished via OR/ORD calculations with cross-validation by ECD and VCD.
摘要：
结构阐明一直是具有挑战性的，在天然产品领域，错误分配仍然是一个严格的问题。对发现未知的兴趣日益增长，复杂的自然结构伴随着人们对社区中错误分配的认识日益提高。近年来，各种光谱方法与分子建模的结合已越来越流行。在这项工作中,我们展示了，第一次,它的能力，以充分阐明2维和3维结构的两个差向异构体的6-羟基hipopethidine的混合物。首先进行化学位移的DFT计算以辅助平面结构的分配。此外，通过三种不同的计算机辅助结构阐明(CASE)结合ORD/ECD/VCD光谱学方法建立了相对和绝对构型.此外,还揭示了OR/ORD计算对相对和绝对构型测定的显著附加价值.值得注意的是,通过OR/ORD计算并通过ECD和VCD进行交叉验证,实现了两种对映体支架(crinine和血色素胺)的分化.
