Nickel-Catalyzed Dimerization of [5]Cumulenes (Hexapentaenes)
Bibliographic Information
- Other Title
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- Nickel Catalyzed Dimerization of 5 Cumulenes Hexapentaenes
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Abstract
<jats:title>Abstract</jats:title> <jats:p>Tetraaryl[5]cumulenes react with low-valent nickel complexes at the second double bond to produce novel [4]radialene derivatives that are head-to-head dimers of [5]cumulenes. The head-to-head dimers are also synthesized by a stepwise route. On the other hand, the nickel-catalyzed dimerization of [5]cumulenes with bulky substituents produces other types of extended [4]radialenes and [5]radialenones depending on the bulkiness of the terminal alkyl substituents. Thus, tetrakis-t-butyl[5]cumulene and 1,4-bis(2,2,6,6-tetramethylcyclohexylidene)[3]cumulene react at the central double bond to give the corresponding [4]radialene and [5]radialenone, whereas 1,4-bis(2,2,5,5-tetramethylcyclopentylidene)[3]cumulene and its benzo-annelated derivative react at the second double bond in a head-to-tail manner to afford the corresponding extended [4]radialenes. Tetrakis-t-butyl[5]radialenone was converted into [5]radialene by using a methylation–dehydration procedure. The extended [4]- and [5]radialenes and [5]radialenones have been fully characterized by spectroscopic analyses, X-ray crystallography, and/or independent chemical synthesis. The properties of these novel exocyclic π-electron systems have been investigated in detail. The aryl-substituted [4]radialenes exhibit facile bond rotation with low energy barriers. The [5]radialene and [5]radialenone form the corresponding cations easily by the addition of an acidic proton. The selectivity of the nickel-catalyzed dimerization of [5]cumulenes is discussed on the basis of theoretical calculations.</jats:p>
Journal
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- Bulletin of the Chemical Society of Japan
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Bulletin of the Chemical Society of Japan 78 (12), 2188-2208, 2005
Tokyo : Chemical Society of Japan
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Details
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- CRID
- 1520291855874957568
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- NII Article ID
- 10017074742
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- NII Book ID
- AA00580132
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- ISSN
- 00092673
- 13480634
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- NDL BIB ID
- 7741492
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- Text Lang
- en
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- NDL Source Classification
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- ZP1(科学技術--化学・化学工業)
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- Data Source
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- NDL
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