Synthesis and Structural Characterization of Novel Organometallic Dehydroannulenes with Fused CpCo-Cyclobutadiene and Ferrocene Units Including a Cyclic Fullerenyne Segment

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• 作者：Uwe H. F. Bunz ; Gaby Roidl ; Markus Altmann ; Volker Enkelmann ; and Ken D. Shimizu
• 刊名：Journal of the American Chemical Society
• 出版年：1999
• 出版时间：November 24, 1999
• 年：1999
• 卷：121
• 期：46
• 页码：10719 - 10726
• 全文大小：298K
• 年卷期：v.121,no.46(November 24, 1999)
• ISSN：1520-5126

文摘

The synthesis of fused organometallic dehydroannulenes containing cyclobutadiene(cyclopentadienyl)cobalt or ferrocene units separated by butadiyne linkers is presented. Starting from the corresponding 1,2-diethynylated sandwich complexes, either Eglinton, Hay, or Vögtle-type coupling furnishes the desireddehydroannulenes. The choice of the coupling variant is critical for the success of this reaction. It was foundthat for diethynylferrocene a variant of the classic Eglinton system utilizing a Cu₂Cl₂/CuCl₂ mixture in pyridineworks successfully, while for the case of the cyclobutadiene(cyclopentadienyl)cobalt complexes the Vögtlecoupling utilizing Cu(OAc)₂ in acetonitrile gave the most impressive results, leading to a 87% yield of cyclizedmaterial. To obtain perethynylated organometallic dehydroannulenes, a novel synthesis of tetraethynylatedcyclobutadiene complexes was developed. Flash vacuum pyrolysis of a bisbutadiynylated CpCo-ligatedcyclobutadiene furnishes the desired tetraethynylated cyclobutadiene complex via a Bergman-type rearrangement.The two TMS and two TIPS substituents of the cyclobutadiene complex are oriented pairwise ortho withrespect to each other. Removal of the TMS groups accesses a monomer, which under the conditions of theVögtle coupling cyclizes to novel trimeric and tetrameric, perethynylated, cyclobutadieno fused, organometallicdehydroannulenes.