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Publication 129  

  1. Catalytic Intramolecular Palladium-Ene Reactions. Preliminay Communication
    Oppolzer, W.; Gaudin, J.-M.
    Helv. Chim. Acta 1987, 70, 1477-1481

Pd(dba)2[dba = dibenzylideneacetone]/PPh3-or Pd(PPh3)4-catalyzed cyclizations of acetoxy-dienes 2 → 3 and 10 → 11 gave 1-vinyl-2-methylidene-subsituted cyclopentances and cyclohexanes in high yield, consistent with a palladium-ene/β-elimination mechanism (D → E → F, Scheme 2). The efficient and highly stereoselective cyclizations 7 → 7 and 8 → 9 illustrate intramolecular allylpalladium insertions into 1,2-dialkyl-, trialkyl-, trialkyl-, and cyclic alkenes followed by elimination of the exocyclic β–H giving 1,2-divinylcyclopentanes. These new olefin insertions proceed faster in AcOH (compared to THF) and occur preferentially cis relative to the Pd (13 → 14 → 15).

DOI : 10.1002/hlca.19870700604 

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