McMurry reactions of (脦脦⁵-acetylcyclopentadienyl) cobalt-(脦脦⁴-tetraphenylcyclobutadiene) with benzophenone: ketone couplings and a pinacol/pinacolone rearrangement

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• 作者：Ortin ; Yannick ; Grealis ; John ; Scully ; Conor ; M脙脙ller-Bunz ; Helge ; Manning ; Anthony R. ; McGlinchey ; Michael J.
• 关键词：Cyclobutadiene脙脙脙脙脙脙cobalt complexes ; McMurry couplings ; X-ray crystallography ; Pinacol rearrangement
• 刊名：Journal of Organometallic Chemistry
• 出版年：2004
• 期刊代码：64_0022328x
• 类别：ch
• 出版时间：December 6, 2004
• 卷：689
• 期：25
• 页码：4683-4690
• 文件大小：663 K

摘要

The reaction of (脦脦⁴-C₄Ph₄) Co[脦脦⁵-C₅H₄脦脦脦C(O)Me], 5, with benzophenone under McMurry conditions (TiCl₄/Zn/THF) gives the hetero-coupled product (脦脦⁴-C₄Ph₄)Co[脦脦⁵-C₅H₄脦脦脦C(Me)CPh₂], 7, together with the dicobalt species: trans-(脦脦⁴-C₄Ph₄)Co[(脦脦⁵-C₅H₄脦脦脦C(Me)C(Me)-脦脦⁵-C₅H_4脦脦脦)] Co(脦脦⁴-C₄Ph₄), 9, and the pinacolone Me[(脦脦⁴-C₄Ph₄)Co(脦脦⁵-C₅H₄)]₂C脦脦脦C(O)Me, 10. The latter is apparently formed from the pinacol by migration of an (脦脦⁴-C₄Ph₄)Co[(脦脦⁵-C₅H₄) group. Preferential migration of the cobalt sandwich moiety rather than a methyl group is rationalized in terms of a favored transition state involving a metal-stabilized cation. The products 7, 9 and 10, and also the ketone (脦脦⁴-C₄Ph₄)Co[脦脦⁵- C₅H₄脦脦脦C(O)Et], 6, were all characterized by X-ray crystallography.