Ruthenium-catalyzed hydration of 1-alkynes to give aldehydes: Insight into anti-Markovnikov regiochemistry

Makoto Tokunaga, T. Suzuki, N. Koga, T. Fukushima, A. Horiuchi, Y. Wakatsuki

Research output: Contribution to journalArticlepeer-review

195 Citations (Scopus)

Abstract

The mechanism of the selective conversion of 1-alkynes to aldehydes by hydration was investigated by isolating organic and organometallic byproducts, deuterium-labeling experiments, and DFT calculations. The D-labeled acetylenic hydrogen of 1-alkyne was found exclusively in the formyl group of the resulting aldehydes. After the reaction, the presence of metal-coordinated CO was confirmed. All of the experimental results strongly suggest the involvement of a metal-acyl intermediate with the original acetylenic hydrogen also bound to the metal center as a hydride, with the next step being release of aldehyde by reductive elimination. Theoretical analyses suggest that the first step of the catalytic cycle is not oxidative addition of acetylene C-H or tautomerization of η2-alkyne to a vinylidene complex, but rather protonation of the coordinated 1-alkyne at the substituted carbon to form a metal-vinyl intermediate. This cationic intermediate then isomerizes to Ru(IV)-hydride-vinylidene via α-hydride migration of the vinyl group to the metal center, followed by attack of the vinylidene α-carbon by OH- to give the metal-hydride-acyl intermediate.

Original languageEnglish
Pages (from-to)11917-11924
Number of pages8
JournalJournal of the American Chemical Society
Volume123
Issue number48
DOIs
Publication statusPublished - Dec 5 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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