ARYLATION OF STYRENE BY PALLADIUM ACETATE-PHOSPHINE COMPLEXES

When phenylation of styrene was carried out in the presence of Pd(OAc) (2) and PPh(3) in benzene, trans-stilbene was obtained in good yield ( 566%) with high selectivity (98%) under mild condition (55.degrees C, 50 psi O-2, 20 h). Since trans-stilbene could be produced not only fro m benzene but also from phenyl group of PPh, by migration of its pheny l group to Pd, the competitiveness of benzene and the migratory aptitu de of aryl group of triarylphosphine toward styrene has been investiga ted with various phosphines (PR(3):P(p-C6H4CH3)(3), P(p-C6H4 OCH3)(3), P(p-C6H4F)(3), P(p-C(6)H(4)C1)(3), P(C6H5)(3), P(OC4H9'')(3), P(CH2C6 H5)(3), P(CH2C6H5)(3) and P(C6F5)(3)). The yield and selectivity towar d trans-stilbene are increased as the basicity of the phosphines incre ases. The composition of arylated olefin from arylphosphine, in turn, increases as the electronegativity of the substituent on the aryl grou p of arylphosphines increases.