Chemistry of palladium phosphinite (PPh₂(OR)) and phosphonite (P(OPh)₂(OH)) complexes: catalytic activity in methoxycarbonylation and Heck coupling reactions

Abstract

The new phosphinite and phosphonite complexes (1-8) are very efficient catalysts for the methoxycarbonylation of iodobenzene and Heck cross-coupling of bromobenzene with butyl acrylate. High catalytic activity of these complexes can be explained by their in situ transformations during the reaction, stimulated by the presence of water, acid (HCl) or base (NEt(3)). Hydrolysis of phosphinite palladium complexes of the form trans-PdCl(2)[PPh(2)(OR)](2) (R = C(6)F(5), 2, (t)Bu 3, or O-menthyl 4) results in the formation of the dimeric complex [mu-ClPd(PPh(2)OH)(PPh(2)O)](2) 5, which is deprotonated by NEt(3), producing a polymeric complex of formula [Pd(P(O)PPh(2))(2)](n) 8. The reverse reaction, protonolysis of 8 with HCl, leads back to 5 and the monomeric complex 5a. The phosphinite complex PdCl(2)[PPh(2)(OBu)](2)1 with a more lipophilic ligand, PPh(2)(OBu), does not undergo hydrolysis under the same conditions. In the reaction of PdCl(2)(cod) with P(OPh)(2)(OH), the new dimer [mu-ClPd(P(OPh)(2)OH)(P(OPh)(2)O)](2) 6 was obtained, whereas reaction of Pd(OAc)(2) with P(OPh)(2)(OH) leads to the polymeric complex [Pd[P(O)(OPh)(2)](2)](n) 7. Protonolysis of 7 with HCl results in the formation of 6.

Crystal structure of bis(μ 2-chlorido)-bis(di-p-tolylhydroxyphosphine-κP)-bis(di-p-tolylphosphite-κP)dipalladium(II), C56H58Cl2O4P4Pd2

“…Palladium catalysts, more speci cally those containing phosphine ligands have been intensively studied in homogeneous catalytic reactions such as the Heck and Suzuki cross coupling reaction [1][2][3][4][5][6]. The title compound forms part of an ongoing research study on the synthesis of highly selective and air stable phosphine ligands coordinated to platinum and palladium to ensure minimal by-product formation and to strengthen catalyst stability.…”

Anionic phosph(in)ito (“phosphoryl”) ligands: Non-classical “actor” phosphane-type ligands in coordination chemistry

“…Lately, bidentate mono O−anionic  1 -P(III)−phosph(in)ite complexes have been involved in a large number of catalytic transformations [176,177,[200][201][202][203][204][205][206].…”

2-Aminophenyl diphenylphosphinite as a new ligand for heterogeneous palladium-catalyzed Heck–Mizoroki reactions in water in the absence of any organic co-solvent

“…33,34 We have also reported an imidazolium-based phosphinite ionic liquid as a medium and a ligand in the Heck-Mizoroki reaction, dehalogenation and homocoupling of aryl halides in the presence of PdCl 2 . 32 Now, we report efficient Heck-Mizoroki reaction of various aryl halides in the presence of an easily prepared 2-aminophenyl diphenylphosphinite as a ligand in water in the absence of any organic co-solvent.…”