Oxidative Dimerization of Silylallenes via Activation
of the Allenic C(<i>sp</i><sup>2</sup>)–H Bond Catalyzed
by Copper(I) Chloride and <i>N</i>‑Hydroxyphthalimide
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Abstract
Novel
oxidative dimerization of silylallenes is described. Treatment
of silylallenes with a catalytic amount of copper(I) chloride, a substoichiometric
amount of <i>N</i>-hydroxyphthalamide, and a stoichiometric
amount of a terminal oxidant diacetoxyiodobenzene afforded head-to-head
dimers as the main products. Silyallenes containing a small ring afforded
only dimers, whereas as the ring size increased 1,3-enynes became
more favorable products. For silylallenes containing an acyclic substituent,
dimer formation is a norm with exceptions where <i>N</i>-hydroxyphthalimide reacts at the propargylic center to generate
the corresponding aminoxy ethers