Development of highly sensitive NMR spectroscopic techniques and their application to structural analysis of natural products

在订购开发高度敏感的核磁共振技术时，该技术将使复杂的自然产品的满足性工厂结构信息仅在较小数量中可用，我们将尝试通过修改2D-核磁共振技术来创建新的脉冲序列，以实现1D-核磁共振版本。在这些过程中，我们发现了一个具有非常高选择性的辐射场，可以通过使用时间共享栅极衰减（TSD）来创造，为这些目的提供了非常好的结果。由于部署了这个辐射场和90度复合脉冲，我们成功地开发了一种新的Noe技术，命名为时间共享门控解码Noe （TSD-NOE），在传统的Noe实验上有一些进步。作为下一步，我们应用TSD来获得解码差异规格，并可能开发新的脉冲技术，命名为TSD-COSY和TSD-ayed-COSY。在这些技术中，TSD创建了一个高度选择性的辐射场，用于饱和一个特定的质子，从而导致了质子对饱和质子的信号强度的下降。在进一步详细的实验之后，我们成功地设置了最好的实验条件，在几个实验因素上释放了诸如延迟时间和字段强度等方面，然后我们开发了一种新的技术，命名为选择性HOHAHA-CH，该技术被用于揭示一个给定质子的关系和附着在同一质子自旋系统中的碳原子。因此，由于这项技术的应用，它可能会非常有效地携带复杂分子的结构分析工作。一种新的核苷酸抗生物移植物的结构是通过应用于这个新的脉冲序列来确定的。在补充中，我们报告了HMBC对自然产品的结构研究，如多甲基化合物和萜类的结构研究。

In order to develop highly sensitive NMR techniques, which enable to obtain satisfactory structural information of complicated natural products only available in a small quantity, we attempted to create new pulse sequences by modification of 2D-NMR techniques to 1D-NMR version. During these process, we found that an irradiation field with very high selectivity, which could be created by the use time sharing gated decoupling (TSD), gave very good results for these purposes. By employing this irradiation field and 90゜ composite pulse, we succeeded in developing a new noe technique named time sharing gated decoupling noe (TSD-NOE) which has several advantages over conventional noe experiments.As a next step, we applied TSD for obtaining decoupling difference spectra and could develop new pulse techniques named TSD-COSY and TSD-relayed-COSY. In these techniques, a highly selective irradiation field created by TSD was employed to saturate a specific proton to cause the decrease of signal intensities of the protons coupled to the saturated protons. After further detailed experiments, we succeeded in set up best experimental conditions which relied upon several experimental factors such as delay time and field strength.Next we developed a new technique named selective HOHAHA-CH which facilitated to reveal the relationship of a given proton and the carbons attached to the protons involved in the same proton spin system. Thus, by application of this technique, it has become possible to carry out very efficiently the structural analytical works of complex molecules. The structure of a new nucleoside antibiotic portmicin was determined by application of this new pulse sequence. In addition, we reported that HMBC wasparticularly useful for structural studies of natural products such as polyketides and terpenes with many methyl groups.