Regioselective hydroesterification of styrene catalyzed by cationic palladium(II) complexes under mild conditions was written by Oi, S.;Nomura, M.;Aiko, T.;Inoue, Y.. And the article was included in Journal of Molecular Catalysis A: Chemical in 1997.Electric Literature of C33H25OP This article mentions the following:
The cationic palladium(II) complex [Pd(MeCN)2(PPh3)2](BF4)2 was found to be an active catalyst for hydroesterification (alkoxycarbonylation) of styrene using CO and methanol under very mild conditions. The system, Pd(OAc)2-PPh3–p-toluenesulfonic acid, which should give rise to a cationic species in situ, was also effective to produce the branched ester regioselectively in an excellent yield at ambient temperature Asym. hydroesterification of styrene by the use of chiral phosphines as ligands was also studied. The hydroesterification of 4-isobutylstyrene gave α-methyl-4-(2-methylpropyl)benzeneacetic acid Me ester (i.e., ibuprofen Me ester). Also prepared was (S)-6-methoxy-α-methyl-2-naphthaleneacetic acid Me ester. In the experiment, the researchers used many compounds, for example, (S)-(2′-Methoxy-[1,1′-binaphthalen]-2-yl)diphenylphosphine (cas: 134484-36-9Electric Literature of C33H25OP).
(S)-(2′-Methoxy-[1,1′-binaphthalen]-2-yl)diphenylphosphine (cas: 134484-36-9) belongs to chiral phosphine ligands. The synthesis of novel trialkylphosphines can be quite difficult, thereby limiting the scope of their chiral variants. Indeed, very little research on chiral tertiary phosphine-catalyzed asymmetric reactions occurred prior to the year 2000.Electric Literature of C33H25OP
Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis