Rhodium-Catalyzed Silylative and Germylative Cyclization with Dehydrogenation Leading to 9-Sila- and 9-Germafluorenes: A Combined Experimental and Computational Mechanistic Study

Masahito Murai, Ryo Okada, Sobi Asako, Kazuhiko Takai

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Stoichiometric amounts of oxidants are widely used as promoters (hydrogen acceptors) in dehydrogenative silylation of C−H bonds. However, the present study demonstrates that silylative and germylative cyclization with dehydrogenation can proceed efficiently, even without hydrogen acceptors. The combination of [RhCl(cod)]2 and PPh3 was effective for both transformations, and allowed a reduction in reaction temperature compared with our previous report. Monitoring of the reactions revealed that both transformations had an induction period for the early stage, and that the rate constant of dehydrogenative germylation was greater than that of dehydrogenative silylation. Competitive reactions in the presence of 3,3-dimethyl-1-butene indicated that the ratio of dehydrogenative metalation and hydrometalation was affected by reaction temperature when a hydrosilane or hydrogermane precursor was used. Further mechanistic insights of oxidant-free dehydrogenative silylation, including the origin of these unique reactivities, were obtained by density functional theory studies.

Original languageEnglish
Pages (from-to)10861-10870
Number of pages10
JournalChemistry - A European Journal
Volume23
Issue number45
DOIs
Publication statusPublished - Jan 1 2017

Keywords

  • C−H activation
  • dehydrogenation
  • germylation
  • rhodium
  • silylation

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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