Regioselective palladium-catalyzed electrophilic allylic substitution in the presence of hexamethylditin.
[reaction: see text]. Palladium-catalyzed electrophilic allylic substitution of functionalized allyl chlorides and allyl acetates can be achieved in the presence of hexamethylditin under mild reaction conditions. The substitution reaction occurs with very high regioselectivity at the branched allylic terminus. Regioselective tandem bisallylation reaction could be performed by employing benzylidenemalonitrile as substrate. The reaction mechanism can be explained by involvement of a bisallylpalladium intermediate. A particularly interesting mechanistic feature of this reaction is that palladium catalyzes up to three different transformations in the same catalytic cycle. DFT calculations indicate that the regioselectivity is determined by the location of the allylic substituent in the eta1-allyl moiety of the reaction intermediate.
Wallner
Olov A
OA
Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
Szabó
Kálmán J
KJ