Cobalt-Catalyzed E-Selective Cross-Dimerization of Terminal Alkynes: A Mechanism Involving Cobalt(0/II) Redox Cycles
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Updated: Jan 4, 2026

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Published on: November 9, 2019
Yohei Ueda1, Hayato Tsurugi1, Kazushi Mashima1
1Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
Abstract:
A highly E-selective cross-dimerization of terminal alkynes with either terminal silylacetylenes, tert-butylacetylene, or 1-trimethylsilyloxy-1,1-diphenyl-2-propyne in the presence of a dichlorocobalt(II) complex bearing a sterically demanding 2,9-bis(2,4,6-triisopropylphenyl)-1,10-phenanthroline, activated with two equivalents of EtMgBr, gives a variety of (E)-1,3-enynes. A well-characterized diolefin/cobalt(0) complex, with divinyltetramethyldisiloxane, acted as a catalytically active species without any activation, clearly indicating that a cobalt(0) species is involved in the catalytic cycle.
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