1992 Fiscal Year Final Research Report Summary
Synthesis and Reactions of 2-Aminotropone-imines Directed toward Synthesis of Tropones Having a Carbon Side-chain
| Project/Area Number |
03640458
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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 | Kumamoto University |
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Principal Investigator |
IMAFUKU Kimiaki Kumamoto University, Faculty of Science, Department of Chemistry, Associate Professor, 理学部, 助教授 (20040115)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Seven-membered aromatics / Tropolone / Carbon-chain introduction / Friedel-Crafts reaction / 2-Aminotroponeimine / Dihydro- 1H-cyclohepta[b]pyrazine / N-Acylation / Butyllithium-mediated acylation |
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| Research Abstract |
Friedel-Crafts reaction is an excellent method for introducing a carbon side chain onto an benzenoid aromatic ring. However, the reaction is not applicable to tropolone derivatives because tropolones form metal complexes with catalyst such as aluminum chloride. In order to overcome this defect, we studied the synthesis and reactions of N,N'-dialkyl- and N,N'-diaryl-2-aminotroponeimines.
(1) Synthesis of 2-Aminotroponeimines : Seven N,N'-dialkyl-2-aminotroponeimines were obtained by the reactions of cyclohepta[b]-[1,4]benzoxazine with aliphatic amines, while the reactions with aromatic amines did not give the corresponding 2-aminotroponeimines. The N,N'-diaryl-2-aminotroponeimines were prepared by the reactions of 1,7,7-trichlorotropilidene with anilines. A new synthon, 1,2-di-chlorotropylium salt, was also obtained.
(2) Reactions of 2-Aminotroponeimines : N,N'-Dialkyl-2-aminotroponeimines reacted with bromine and nitric acid to yield 5-bromo-and 5-nitro-N,N'-dialkyl-2-aminotroponeimines, respectively, but Friedel-Crafts acylation was not achieved. The reactions of 2,3-di-hydro-1H-cyclohepta[b]pyrazine, which is cyclic analog of 2-aminotroponeimines, with acyl chloride gave N-acylated products and pyrazine ring-opened ones. On the other hand, 5-bromo-N,N'-dibenzyl-2-amino-troponeimine reacted with ethyl acetate and methyl formate in the presence of buthyllithium to afford 5-acetyl- and 5-formyl-2-aminotroponeimine, respectively. The former was hydrolyzed to yield 5-acetyl-tropolone via 5-acetyl-2-benzylaminotropone.
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