34 天然有機化合物の構造解析を指向した立体化学を考慮する^<13>C-NMR化学シフト予測システムCAST/CNMRの開発(口頭発表の部)

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Stereochemistry is an essential attribute for accurate NMR chemical shift prediction. We have developed a new computer system CAST/CNMR for ^<13>C-NMR chemical shift prediction considering stereochemistry, efficiently, for structure analyses of natural products. Prediction by CAST/CNMR is based on a structure-observed ^<13>C-NMR chemical shift database where structural information including stereochemistry are systematically and canonically described by the CAST (CAnonical-representation of STereochemistry) coding method, which was developed for this purpose. CAST code is based on dihedral angles that are uniquely defined by a molecular tree structure. A model database was constructed by using data of terpenoids, polyketides, and polyethers for the applications. Synthetic compounds are also used for construction of the database. The prediction is performed by matching with the database considering structures from an atom to be predicted to arbitrary level specified by the user. In the present study, structural environments including relative stereochemistry to γ-level are mainly considered. Size of rings was also considered in some applications for more highly accurate prediction. Predictions of ^<13>C-chemical shifts by CAST/CNMR were examined for some terpenoids such as arisugacin F, 17-deoxyaphidicolin, 20-hydroxyecdysone, deoxoscalarin-3-one (1), and 12-epi-deoxoscalarin-3-one (2). Highly accurate ^<13>C-NMR chemical shifts were predicted for them by considering stereochemistry. Some miss-assignments in literatures were also found during the examinations. CAST/CNMR gave good results to assign the ^<13>C-NMR chemical shift for hemibrevetoxin B (3).
天然有機化合物討論会の論文
2001-09-01

34 天然有機化合物の構造解析を指向した立体化学を考慮する^<13>C-NMR化学シフト予測システムCAST/CNMRの開発(口頭発表の部)

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