Cationic palladium(II)-acetylacetonate complexes containing phosphine and aminophosphine ligands and their catalytic activities in telomerization of 1,3-butadiene with methanol

The Pd(II) complexes [Pd(acac)(L)(n)]BF4 were synthesized by the reaction of [Pd(acac)(MeCN)(2)]BF4 with L (n = 2: L = PCyPh2, PCy2Ph, P(NMe2)(3), P(NEt2)(3), tri-2-furylphosphine, tri-2-thienylphosphine; n = 1: L = 2 dicyclohexylphosphino-2',6'-dimethoxybiphenyl, 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl). The structural features of the complexes were analyzed by NMR and FTIR spectroscopies. Complexes [Pd(acac)(PCyPh2)(2)]BF4 and [Pd(acac)(PCy2Ph)(2)]BF4 were characterized by X-ray diffractometry. The cationic palladium catalyst precursors were found to be active catalysts for telomerization of 1,3- butadiene with methanol under base-free conditions. Complexes [(acac)Pd(PCy2Ph)(2)]BF4 and [(acac) Pd(TOMPP)(2)]BF4 in terms of yield, selectivity, and stability are effective for the catalytic telomerization (TOMPP = tris(2-methoxyphenyl)phosphine). Using 0.001-0.0025 mol% palladium loading methoxy-2,7-octadienes were obtained with chemoselectivities of 76-94% and TON up to 60000 mol 1,3-butadiene per mol Pd. (C) 2020 Elsevier B.V. All rights reserved.