68 マキ属植物のノルジテルペンジラクトン類の^<13>C-nmrについて

概要

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^<13>C-nmr spectra have been determined with some twenty members of the biologically active nor-diterpenoid dilactones obtained from Podocarpus nagi. The assignment of each carbon signal was confirmed by proton selective decouplings, J_<C-H> measurements and analogies with the model compounds (Table 1〜4). Detailed analyses were performed firstly with nagilactones, B (3), C (15), D (17) and E (22), and their acetates, relatively abundant dilactones in natural sources, and the results were then adjusted by comparisons with the spectra of other minor related lactones. Characteristic shieldings were observed on the particular carbon atoms, C^7, C^<11>, C^<14> and C^<15>, which would be caused by significant non-bonded interactions in these rigid molecules. Acetylation of the hydroxyl groups on ring A and B also gave rise to some shielding on the neighboring carbon atoms which may be interpreted by γ-effect of the acetyl carbonyl group.
天然有機化合物討論会の論文
1978-08-22