| Research Abstract |
In our studies on total synthesis of alkaloids, aldeemin, amiauromine, flustramine, and peudophynrynaminol, consisting the pyrrolo[2,3-b]indole structure, we have succeeded in synthesis of the desired 3a-allylpyrrolo[2,3-b]indole and in first total synthesis of marine natural product, flustramine C ;
1.We found the new methodology for synthesis of 3a-allylpyrrolo[2,3-b]indole ; the tandem reactions, olefination, isomerization, and Claisen rearrangement of 2-(3,3-dimethylallyl)indolin-3-one produced 3,3-disubstituted oxindole, which was reduced to give 3a-(1, 1-dimethylallyl)-pyrrolo[2,3-b]indole. We succeeded in the first total synthesis of marine natural product, flustramine C utilizing our methodology.
2.The tandem reactions introduced directly two different substituents to 3-site of indole nucleus, and this procedure is a general method for synthesis of 3,3-disubstituted oxindoles.
3.The asymmetric version of the above-mentioned tandem reactions was tried ; olefination, isomerization and Claisen rearrangement of optically active 2-allylindolin-3-one, which was derived from optical active allyl alcohol and 2-bromoindolin-3-one, proceeded stereoselectively to give optically active oxindole in good yield.
4.The reaction of a several kind of 2-allylindolin-3-ones with optically active ylides, followed by isomerization to proceed diastereoselective Claisen rearrangement to afford the oxindole, of which diastereomers were easily separated by silica gel column chromatography to give optically active oxindoles.
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