Tandem intramolecular silylformylation and silicon-assisted cross-coupling reactions. Synthesis of geometrically defined α,β-unsaturated aldehydes

Scott E. Denmark, Tetsuya Kobayashi

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Abstract

The palladium- and copper-catalyzed cross-coupling reactions of cyclic silyl ethers with aryl iodides are reported. Silyl ethers 3 were readily prepared by intramolecular silylformylation of homopropargyl silyl ethers 2 under a carbon monoxide atmosphere. The reaction of cyclic silyl ethers 3 with various aryl iodides 7 in the presence of [(allyl)PdCl]2, CuI, a hydrosilane, and KF·2H2O in DMF at room temperature provided the α,β-unsaturated aldehyde coupling products 8 in high yields. The need for copper in this process suggested that transmetalation from silicon to copper is an important step in the mechanism. Although siloxane 3 and the product 8 are not stable under basic conditions, KF·2H2O provided the appropriate balance of reactivity toward silicon and reduced basicity. The addition of a hydrosilane to [(allyl)PdCl]2 was needed to reduce the palladium(II) to the active palladium(0) form.

Original languageEnglish (US)
Pages (from-to)5153-5159
Number of pages7
JournalJournal of Organic Chemistry
Volume68
Issue number13
DOIs
StatePublished - Jun 27 2003

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ASJC Scopus subject areas

  • Organic Chemistry

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