title: Mercaptobenzoic acid-palladium(0) complexes as active catalysts for S-benzylation with benzylic alcohols via (η(3)-benzyl)palladium(II) cations in water.
abstract: Mercaptobenzoic acid-palladium(0) complexes show high catalytic activity for S-benzylation with benzylic alcohols via the (η(3)-benzyl)palladium(II) cation in water. Notably, these palladium(0) complexes could play an important role in formation of active (η(3)-benzyl)palladium(II) cation complexes followed by S-benzylation. Hammett studies on the rate constants of S-benzylation by various substituted alcohols show good correlation between log(kX/kH) and the σ(+) value of the respective substituents. From the slope, negative ρ values are obtained, suggesting that there is a build-up of positive charge in the transition state. Water plays an important role in the catalytic system for sp(3) C-O bond activation and stabilization of the activated Pd(II) cation species. The catalytic system can be performed using only 2.5 mol% Pd2(dba)3 without the phosphine ligand or other additives.
authors.affiliation: Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan. hidemasa.hikawa@phar.toho-u.ac.jp isao.azumaya@phar.toho-u.ac.jp.
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Hikawa
authors.forename: Isao
authors.initials: I
authors.lastname: Azumaya
mesh_terms: D001565:Benzoates / Q000737:chemistry*; D019905:Benzyl Alcohol / Q000737:chemistry*; D002384:Catalysis; D002412:Cations; D004220:Disulfides / Q000737:chemistry; D007700:Kinetics; D010165:Palladium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D001565:Benzoates; D002412:Cations; D004220:Disulfides; D012997:Solvents; D013438:Sulfhydryl Compounds; D014867:Water; D010165:Palladium; D019905:Benzyl Alcohol