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Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes
Published on: September 8, 2013
Iridium-catalyzed arene ortho-silylation by formal hydroxyl-directed C-H activation
Eric M Simmons1, John F Hartwig
1Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA.
Abstract:
A strategy for the ortho-silylation of aryl ketone, benzaldehyde, and benzyl alcohol derivatives has been developed in which a hydroxyl group formally serves as the directing element for Ir-catalyzed arene C-H bond activation. One-pot generation of a (hydrido)silyl ether from the carbonyl compound or alcohol is followed by dehydrogenative cyclization at 80-100 °C in the presence of norbornene as a hydrogen acceptor and the combination of 1 mol % [Ir(cod)OMe]2 and 1,10-phenanthroline as a catalyst to form benzoxasiloles. The synthetic utility of the benzoxasilole products is demonstrated by conversion to phenol or biaryl derivatives by Tamao-Fleming oxidation or Hiyama cross-coupling. Both of these transformations of the C-H silylation products exploit the Si-O bond in the system and proceed by activation of the silyl moiety with hydroxide, rather than fluoride.
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