安定に単離できる5員環アルキン化合物 [in Japanese] Stable Five-Membered Cyclic Alkynes [in Japanese]
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It is generally known that small cyclic alkynes such as cyclopentyne is extremely reactive and unstable. Therefore it has been believed impossible to isolate cyclopentyne compounds.<BR>We recently reported that low-valent group 4 metallocenes reacted with 1, 2, 3-butatrienes to give 1-metallacyclopent-3-yne complexes and that resulted compounds are surprisingly stable and isolable. We succeeded in determination of their molecular structures by X-ray diffraction analyses, and showed that these are five-membered cyclic alkynes, while π, π-interaction of butatriene was also suggested. In this review, the preparation, structure and reactivity of these 1-metallacyclopent-3-yne compounds are described.<BR>The 1-zirconacyclopent-3-yne complexes reacted with another 'zirconocene' to form bimetallic complexes in which the cyclic alkyne coordinated to the other zirconocene moiety, indicating that the zirconacyclopentyne behaved as an alkyne. Seven-membered cyclic alkynes were also prepared from 1, 2, 3-butatriene and a zirconocene-alkyne compound. Protonolysis and subsequent nucleophilic attack to aldehyde gave allenyl or dienyl alcohol depending on proton source.
- J. Synth. Org. Chem. Jpn.
J. Synth. Org. Chem. Jpn. 65(4), 347-357, 2007-04-01
The Society of Synthetic Organic Chemistry, Japan