Allenes as carbon nucleophiles in palladium-catalyzed reactions: observation of anti attack of allenes on (pi-allyl)palladium complexes.

In the palladium-catalyzed cyclization of allenic allylic esters using Pd(dba)2 as catalyst, it was shown that the allene acts as a carbon nucleophile. Intermediates were isolated and stereochemical studies established that the double bond of the allene has attacked the (pi-allyl)palladium intermediate on the face opposite to that of palladium.