PS-PAr₃ Hybrid: Metal Complexation and Catalytic Applications

Key words

cross-coupling - borylation - polystyrene - phosphine ligands

Significance

The polystyrene triarylphosphine hybrid 1 was prepared by radical emulsion polymerization of 4-tert-butylstyrene, divinylbenzene, and tris(4-vinylphenyl)phosphine (eq. 1). The cross-coupling of arylchlorides with phenylboronic acid and amines in the presence of Pd–1 complexes, generated in situ, gave the corresponding coupling products (eqs. 2 and 3). Supported phosphine 1 was also effective for the iridium- or rhodium-catalyzed borylation of C(sp³)–H bonds to afford the corresponding borylated products (eqs. 4–6).

Comment

PS-PAr₃ 1 was characterized with ¹³C and ³¹P CP-MAS NMR. In the Suzuki–­Miyaura cross-coupling of 4-chlorotoluene with phenylboronic acid, the catalyst was recovered by simple filtration and reused with a decrease in catalytic activity (1^st use: 91% yield, 3^rd reuse: 94% yield, 4^th reuse: 85% yield, 5^th reuse: 70% yield, 6^th reuse: 47% yield, 7^th reuse: 24% yield). After the third reuse, TEM analysis of the recovered catalyst showed the aggregation of palladium metal.