Allenes as carbon nucleophiles in intramolecular attack on (pi-1,3-diene)palladium complexes : Evidence for trans carbopalladation of the 1,3-diene

• Reaction of allene-substituted cyclohexa- and cyclohepta-1,3-dienes with [PdCl2(PhCN)(2)] gave eta(3)-( 1,2,3)-cyclohexenyl- and eta(3)-(1,2,3)-cycloheptenylpalladium complexes. respectively. in which C-C bond formation between the allene and the 1.3-diene has occurred. Analysis of the (pi-allyl)palladium complexes by NMR spectroscopy. using reporter ligands, shows that the C-C bond formation has occurred by a trans carbopalladation involving nucleophilic attack by the middle carbon atom of the allene on a (pi-diene)palladium(n) complex. The stereochemistry of the (pi-allyl)palladium complexes was confirmed by benzoquinone-induced stereoselective transformations to allylic acetates.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

C-C coupling

carbopalladation

palladium

reaction mechanisms

Chemistry

Kemi

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ref (ämneskategori)

art (ämneskategori)