| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1998: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1997: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Synthetic methodologies for the construction of carbon-carbon unsaturated bond systems have been much attention because of their existence in a wide variety of organic compounds. This research project is concerned with the development of novel types of reactions providing simple, effective routes to construct unsaturated bond systems by using transition metal catalysts.
Conjugated enediyne compounds are of importance since they are known as a key structure of some antitumor agents. The investigator found a new synthetic route to enediynes starting from propargylic carbonates and terminal alkynes. In the presence of a palladium catalyst, a propargylic carbonate was coupled with 2 moles of terminal alkynes affording the corresponding coupling products having a conjugated enediyne structure in good yield. The reaction proceeded step by step in one pot, thus an unsymmetrical enediyne compound could be also synthesized by successive addition of two different alkynes.
In the course of the study, the investigator found that an allenylcyclopropane, one of the intermediate compounds in the coupling reaction described above, could be transformed into a methylenecyclopentene via a ring-expanding rearrangement, when it was treated with rhodium catalysts. This novel rhodium-catalyzed transformation reaction of allenylcyclopropanes afforded conjugated diene compounds having an exo-cyclic olefin, 3-methylenecyclopentenes, in a selective manner under quite mild conditions. Highly regioselective carbon-carbon bond cleavage of the cyclopropane ring was observed, when substituted allenylcyclopropanes were allowed to react in the presence of cationic rhodium complexes.
In summary, the investigator has developed two new reactions constructing carbon-carbon unsaturated bond systems by using transition metal catalysts.
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