Preparation of Cyclophanes by Room-Temperature Ring-Closing Alkyne Metathesis with Imidazolin-2-iminato Tungsten Alkylidyne Complexes

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• 作者：Stephan Beer ; Kai Brandhorst ; J&ouml ; rg Grunenberg ; Cristian G. Hrib ; Peter G. Jones ; Matthias Tamm
• 刊名：Organic Letters
• 出版年：2008
• 出版时间：March 6, 2008
• 年：2008
• 卷：10
• 期：5
• 页码：981 - 984
• 全文大小：91K
• 年卷期：v.10,no.5(March 6, 2008)
• ISSN：1523-7052

文摘

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Room-temperature ring-closing alkyne metathesis of 1,2-, 1,3-, and 1,4-bis(3-pentynyloxymethyl)benzenes has been investigated in the presenceof catalytic amounts of an imidazolin-2-iminato tungsten alkylidyne complex. The m- and p-diynes selectively form the respective[10]metacyclophane or [10.10]paracyclophane, respectively, whereas a mixture of monomeric and dimeric cycloalkynes is obtained in the caseof the o-diyne. DFT calculations reveal that the different selectivities can be attributed to the relative thermodynamic stability of the emergingcyclophanes.