Platinum and ruthenium chloride-catalyzed cycloisomerization of 1-alkyl-2-ethynylbenzenes: Interception of π-activated alkynes with a benzylic C-H bond

Mamoru Tobisu, Hiromi Nakai, Naoto Chatani

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102 Citations (Scopus)


(Chemical Equation Presented) Air-stable and commercially available alkynophilicmetal salts, such as PtCl2, PtCl4, and [RuCl2(CO)3]2, catalyze the cycloisomerization of 1-alkyl-2-ethynylbenzenes to produce substituted indenes even at an ambient temperature. Electrophilically activated alkynes can be intercepted by simple benzylic C-Hbonds at primary, secondary, and tertiary carbon centers. Mechanistic studies, such as labeling studies and kinetic isotope and substituent effects, indicate that the cycloisomerization proceeds through the formation of a vinylidene intermediate and turnover-limiting 1,5-shift of benzylic hydrogen.

Original languageEnglish
Pages (from-to)5471-5475
Number of pages5
JournalJournal of Organic Chemistry
Issue number15
Publication statusPublished - 2009 Aug 7
Externally publishedYes


ASJC Scopus subject areas

  • Organic Chemistry

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