Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C-H Activation

Chang Sheng Wang, Sabrina Di Monaco, Anh Ngoc Thai, Md Shafiqur Rahman, Benjamin Piaoxiang Pang, Chen Wang, Naohiko Yoshikai

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

A catalytic system comprising a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines and related azines, imidazo[1,2-a]pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic systems for analogous transformations, the present catalytic systems not only feature convenient setup using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp) but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Meanwhile, the present catalytic system proved to promote exclusively C5-selective alkenylation of imidazo[1,2-a]pyridine derivatives. Mechanistic studies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkenyl(carbamoyl)cobalt intermediate.

Original languageEnglish
Pages (from-to)12878-12889
Number of pages12
JournalJournal of the American Chemical Society
Volume142
Issue number29
DOIs
Publication statusPublished - 2020 Jul 22
Externally publishedYes

ASJC Scopus subject areas

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

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