| Co-Investigator(Kenkyū-buntansha) |
HAGA Kazuo Utsunomiya University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (90008011)
KARIKOMI Michinori Utsunomiya University, Faculty of Engineering, Assistant, 工学部, 助手 (00224709)
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| Research Abstract |
Natural products possess various kinds of carbon skeletons and the development of the efficient preparation methods for these carbon skeletons is one of very important subjects in organic synthesis. In the course of our studies on the synthesis of natural products, we have already investigated the practical methods for the conversion of bridged bicyclic compounds into [m-n] fused-ring compounds, using an anionic [1,3] rearrangement as a key step. We attempted the total synthesis of (±)-junicedranol, a marine sesquiterpene-alcohol with a unique tricycliic skeleton, using the anionic [1,3] rearrangement followed by the Diels-Alder reaction strategy in order to elucidate the synthetic utility of the rearrangement, Moreover, (±)-2-thiocyanatoneopupukeanane, a marine sesquiterpene-thiocyanate with a tricyclo[4.3.1.0^<3,7>]decane skeleton, was prepared through a pinacol-type rearrangement of a bicyclo[2.2.2]oct-5-en-2-ol giving a bicyclo[3.2.1]oct-6-en-2-one derivative and an aldol reaction
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leading to the neopupukeanane framework.
We have also developed a novel methodology for the construction of unique diquinanes, possessing four contiguous methyl groups on their convex, by employing a combination of pinacol-type rearrangement and the anionic [1,3] rearrangement. This stratergy would be applicable to the total synthesis of natural diquinanes, such as ptychanolide and its related compounds. An efficient one-pot synthesis of a 10,10-ethylenebicyclo[5.2.1]dec-8-ene-4-one derivative, which can be considered as a synthetic intermediate for the taxane skelton, has been achieved by tandem anionic [1,3] and oxy-Cope rearrangements of 2-vinylbicyclo[3.2.1] oct-6-en-2-ol.
On the other hand, we have previously reported an efficient anionic [3,3] rearrangement of bridged compounds containing a 1-aryl-3-butenol unit, so-called aromatic oxy-Cope rearrangement. We have then developed a novel synthesis of 2-acetoxy[5]helicene, using this aromatic oxy-Cope rearrangement as a key step. In addtion, this strategy has been applied to a practicall method for the the synthesis of chiral [5]helicenes. The carbonyl groups of the above intermediates can be easily converted to other functional groups, so that these compounds are useful for further synthetic studies of chiral hedical compounds possessing a variety of functionalities. Application of this trategy to the synthesis of other hedical systems are under investigation. Less
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