1998 Fiscal Year Final Research Report Summary
Development of New Skeletal Transformations of Polycyclic Methylenecyclobutyl Ketones and Their Application
| Project/Area Number |
09650959
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Synthetic chemistry
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| Research Institution | NARA INSTITUTE OF SCIENCE AND TECHNOLOGY |
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Principal Investigator |
KAKIUCHI Kiyomi NARA INSTITUTE OF SCIENCE AND TECHNOLOGY,GRADUATE SCHOOL OF MATERIALS SCIENCE,PROFESSOR, 物質創世科学研究科, 教授 (60152592)
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| Co-Investigator(Kenkyū-buntansha) |
KUROSAWA Hideo OSAKA UNIVERSITY,SCHOOL OF ENGINEERING,PROFESSOR, 大学院工学研究科, 教授 (40029343)
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| Project Period (FY) |
1997 – 1998
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| Keywords | polycyclic compounds / methylenecyclobutyl ketone / skeletal transformations / pentalenene / mediterraneol B / taxol / acid catalysts / bridgehead substituents |
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| Research Abstract |
In this research, we have carried out the systematic investigation of skeletal rearrangements of polycyclic methylenecyclobutyl ketones prepared easily by photocycloaddition of corresponding cyclic enones to allene to develop the new method for construction of functional and useful polycyclic compounds. Furthermore, in order to exemplify the utility of the method, we have also done the synthetic study of some terpenoids. Reactions of 6-4-fused ketones bearing alkyl substituents at the C6 with acids such as H2S0_4, p-TsOH, CF_3SO_3H, BF_3 OEt2, FeCl_3, AlCl_3, TiCl_4, and BCl_3 gave various kinds of products. In the cases of the methyl and ethyl derivatives, cyclooctenones were obtained mainly using TiCl_4 and BCl_3, while cyclohexenones were major products using the other acids. In the cases of isopropyl and tert-butyl derivatives, however, bicyclo[4.2.1]nonanones were formed in good yields with TiCl_4 and BCl_3, and bicyclo[4.3.0]nonanones were produced with the other acids. The difference of the reactivity toward acids may be explained by the affinity of the acid to the carbonyl group of the substrate prefer to the exo-methylene moiety. Also, the products can be divided into two groups by acid used, and the difference may be attributed to the stability of the carbocation intermediates dependent on the bridgehead substituents. Utilizing this rearrangement protocol as a key step, total syntheses of (*)-pentalenene and (*)-tetramethylmediterraneol B have been achieved. Furthermore, the synthetic study on the anticancer terpenoid taxol is in progress.
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