PREPARATION OF CONJUGATED HETEROCYCLES BY [4pi+6pi] CYCLOADDITION OF MESOIONIC COMPOUNDS
| Project/Area Number |
03640446
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
有機化学一般
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| Research Institution | SHINSHU UNIVERSITY |
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Principal Investigator |
KATO Hiroshi SHINSHU UNIVERSITY, FACULTY OF SCIENCE, DEPARTMENT OF CHEMISTRY, PROFESSOR, 理学部, 教授 (80020650)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Tomoshige SHINSHU UNIVERSITY, FACULTY OF SCIENCE, DEPARTMENT OF CHEMISTRY, ASSISTANT, 理学部, 助手 (40170336)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1991: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Mesoionic / Tropone / Fulvene / Cycloaddition / Selectivity / Periselectivity / Ylide / 4+6 / 周辺選択性 |
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| Research Abstract |
The in situ formation of a mesoionic 4-oxazolone allowed the formation of the [4pi+6pi] cycloadduct with tropone in good yield. The yields of a pyrazolotropone via [4pi+2pi] cycloadducts of a sydnone and the[4pi+6pi] adduct with a 1,3-dithiolone were increased by addition of copper(II) acetate.
The reaction of mesoionic 5-thiazolones with tropone gave products by deep-seated rearrangement of the cycloadduct. The interrelationship among the products as well as the structures have been discussed.
Theoretical consideration of the regio- and peri-selectivities of these cycloadditions based on PM3-MO calculation has led to the conclusion that the selectivity is governed mainly by steric factors and not by electronic interaction.
A series of photoisomerization of a [4pi+6pi] adduct of a mesoionic 4-oxazolone with tropone was discovered. The structures of the products and mechanism leading to the photoproducts have been elucidated.
A useful method for a practical preparation of 2-t-butyl-6-(dimethylamino)-fulvene has been established. This fulvene reacted with a sydnone, mesoionic 1,3-dithiolone, 1,3,2-oxathiazolone, and 4-oxazolone in a [4pi+6pi] mode. The cycloadducts underwent extrusion of a group of atoms and elimination of dimethylamine under the reaction conditions to give the desired fully unsaturated cyclopenta-thiapyrane, -pyridazine, -thiazine, and -pyrane derivatives, in one step and generally in good yields. These products have been found to have electronic structures isoelectronic with azulene.
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Report
(3 results)
Research Products
(4 results)
