V. Branchadell et al., Density functional study on the regioselectivity of nucleophilic attack in1,3-disubstituted (diphosphino) (eta(3)-allyl)palladium cations, ORGANOMETAL, 18(24), 1999, pp. 4934-4941
A density functional study has been performed to analyze the influence of e
lectronic effects on the regioselectivity of the Tsuji-Trost reaction. Opti
mized geometries of model (diphosphino)(eta(3)-allyl)palladium cations 6 an
d 7 show that for unsymmetrical allyl ligands the shortest Pd-C(terminal) b
ond is the one closest to the most electron-withdrawing group. The calculat
ed energy barriers for the attack of an ammonia molecule at each one of the
terminal allyl carbon atoms of 7b-d predict that nucleophilic attack would
take place preferentially on the carbon atom remote from the most electron
-withdrawing group, in excellent agreement with experimental observations o
n allylic precursors of cations 4.