| Research Abstract |
This project aimed to synthesize novel Terpenoids having ring-fused macrocyclic skeleton, especially trinervitane diterpenoids with tricyclo[7.2.0^<1.16>] hexadecane carbocycle.
1. By applying kinetic resolution of (±)-4-methyl-Hajos-Parrish ketone using baker's yeast reduction, optically pure (R)-2,6-dimethylbicyclo[4.3.0]nona-l-ene-3,7-dione was obtained in good yield. By controlling the reaction time, it was possible to obtain the enantiomer in high optical purity.
2. Synthesis of trinervitane diterpene was examined. Starting from (R)-2,6-dimethylbicyclo[4.3.0]nona-l-ene-3,7-dione described above, various compounds with requisite side chains and oxygen functionarities were prepared. However, attempted formation of the third 11-menbered ring was unsuccessful in almost cases. The desired tricyclic compound was oobtained only by the intramolecular alkylation of a-sulfenyl anion in low yield.
3. Stereoselective synthesis of glabrescol, a novel mneso-type triterpene with five continuously linked tetrahydrofuran rings, was investigated. By applying baker' yeast reduction, asymmetric epoxidation, and asymmetric dihydroxylation as chilarity induction method, a compound having the structure reported for glabrescol was synthesized. But the spectral data were not identical to those of the natural product. Comparison of NMR spectra of Natural and synthetic compounds suggested that the stereochemistry around the central part of molecule is different. However, synthesized meso-compound with different configuration at the central THF ring was not identical to the natural product again. Thus, we could point out that the reported structure of glabrescol is incorrect. But, we could not propose the correct structure.
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