Transition-metal-promoted or -catalyzed exocyclic alkyne insertion via zirconacyclopentene with carborane auxiliary: Formation of symmetric or unsymmetric benzocarboranes
Publication in refereed journal

香港中文大學研究人員
替代計量分析
.

其它資訊
摘要Reactions of Cp
2Zr(μ-Cl)(μ-C
2B
10H
10)Li(OEt
2)
2 with alkynes R
1C≡CR
2 gave as insertion products zirconacyclopentenes incorporating a carboranyl unit, 1,2-[Cp
2ZrC(R
1)=C(R
2)]-1,2-C
2B
10H
10 (1). Treatment of 1 with another type of alkyne R
3C≡CR
4 in the presence of stoichiometric amounts of NiCl
2 and FeCl
3 or a catalytic amount of NiCl
2 afforded symmetric or unsymmetric benzocarboranes. The regioselectivity was dominated by the polarity of the corresponding alkynes. These reactions could also be carried out in one pot, leading to the equivalent of a three-component [2 + 2 + 2] cycloaddition of carboryne and two different alkynes promoted by transition metals. A reaction mechanism was proposed after the isolation and structural characterization of the key intermediate nickelacycle. These results show that nickel complexes are more reactive than the iron ones toward the insertion of alkynes but that the latter do not initiate the trimerization of alkynes, making the insertion of activated alkynes possible. This work also demonstrates that a catalytic amount of nickel works as well as a stoichiometric amount of nickel in the presence of excess FeCl
3 for the reactions. Such a catalytic reaction may shed some light on the development of zirconocene-based catalytic reactions. © 2012 American Chemical Society.
著者Ren S., Qiu Z., Xie Z.
期刊名稱Journal of the American Chemical Society
出版年份2012
月份2
日期15
卷號134
期次6
出版社American Chemical Society
出版地United States
頁次3242 - 3254
國際標準期刊號0002-7863
語言英式英語

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