Cross dimerization of terminal alkynes catalyzed by [(Et2N) 3U][BPh4]

Jiaxi Wang, Moshe Kapon, Jean Claude Berthet, Michel Ephritikhine, Moris S. Eisen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

The cationic complex [(Et2N)3U][BPh4] reacts with a mixture of terminal alkynes inducing the synthesis of the cross dimerization products. For equimolar amounts of aliphatic alkynes ( iPrCCH, tBuCCH) the head-to-tail geminal dimer of iPrCCH and the geminal cross dimer resulting from the insertion of iPrCCH into the U-CCR (R=iPr, tBu) moiety are obtained. When a mixture of PhCCH is reacted with either iPrCCH or tBuCCH, different products are obtained depending on the molar ratio of the alkynes. The dimerization of iPrCCH with an excess of PhCCH produces the geminal head-to-tail cross dimer issued from the insertion of the aliphatic alkyne into the U-CCPh moiety, and the geminal dimer of PhCCH. Inverting the molar ratio of the alkynes and using the deuterium labeled aliphatic alkyne iPrCCD, the deuterated geminal head-to-tail cross dimer is obtained preferentially with small amounts of the deuterated head-to-tail dimer of iPrCCD. The mixture of tBuCCH and PhCCH is converted into the geminal head-to-tail cross dimer in good yield if the former alkyne is in large excess. The addition of external EtNH2 in the cross dimerization of iPrCCH with PhCCH induces a different chemoselectivity producing mainly the cis-dimer of PhCCH. The use of a bulky amine, tBuNH2, with tBuCCH causes the decomposition of the catalytic complex, forming the salt [tBuNH 3][BPh4tBuNH2.

Original languageEnglish
Pages (from-to)183-192
Number of pages10
JournalInorganica Chimica Acta
Volume334
DOIs
StatePublished - 30 May 2002
Externally publishedYes

Keywords

  • Alkynes
  • Borate complex
  • Cationic uranium complex
  • Cross dimerization
  • Dimerization

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