Palladium phosphine derivatives

This operation effectively removes the remaining palladium-containing compounds, phosphine derivatives, and borane residues. 

Hydrosilylation of o-allylstyrene (82) with trichlorosilane in the presence of 0.3mol% of a palladium catalyst bearing triphenylphosphine has been found to produce a mixture of indane (83) and the open-chain products (84) and (85) (Scheme 11). The reaction of styrene with trichlorosilane gave a quantitative yield of 1-phenyl-l-(trichlorosilyl)ethane whereas allylbenzene did not give silylation products under the same reaction conditions. These results show that the hydropalladation process is operative in the hydrosilylation of styrene derivatives with trichlorosilane catalysed by palladium-phosphine complexes." ... 

One of the major problems with these palladium-phosphine catalysts is in that they are rather unstable under the process conditions and gradual loss of the catalytic activity and precipitation of palladium black can often be observed. The introduction of appropriately substituted DPPP derivatives (Scheme 7.16) not only increased the activity over all previous values but largely improved the stability of the catalysts, as well [57],... 

The palladium-phosphine-catalyzed cycloaddition reactions of vinyloxetanes 530 with aryl isocyanates or diaryl-carbodiimides led to 4-vinyl-l,3-oxazin-2-ones 531 or l,3-oxazin-2-imines 532, respectively (Scheme 101). In the absence of phosphine ligands (PPhs, bis(diphenylphosphino)ethane (DPPE), l,3-bis(diphenylphosphino)propane (dppp), no conversion of heterocumulenes was observed. Starting from fused-bicyclic vinyloxetanes, both types of cycloadditions proceeded in a highly stereoselective fashion, affording only the r-isomers of alicycle-condensed 1,3-oxazine derivatives <1999JOC4152>. 

Vinylation of various azoles (pyrrole, indole, carbazole, and their derivatives) with vinyl bromides catalyzed by palladium/phosphine complexes results in the A -vinylazoles in 30-99% yields (Equation 49) <20020L623>. This reaction with cis- and /ra r-P-bromostyrenes is stereospecific giving the respective products with full retention of configuration. 

Fluoride derivatives of palladium(II) and platinum(II), all of which are phosphine derivatives, can be most simply grouped into one of two subsections, namely neutral or cationic species. The neutral species are all of the form [MXF(PPh3)2] (M = Pd, Pt) where X can be Cl, Br, I, H, methyl, phenyl and C6F5. The synthetic route into these compunds involves either addition of HF to a metal phosphine dihalide or... 

Dienes.1 (E)-l-Alkenylalanes, readily obtained by hydroalumination of 1-al-kynes,2 couple with vinyl iodides in the presence of this Pd(0) catalyst and zinc chloride to give 1,3-dienes with retention of the configuration. Alkenylzinc derivatives may be the actual reactants. Nickel catalysts are less stereoselective than palladium-phosphine catalysts. 

By Replacement of Zerovalent Isocyanide Derivatives. This method was described for preparing the tris and tetrakis palladium (0) derivatives with tertiary aromatic phosphines and phosphites 129). It might be extended to nickel. 

By Synthesis from the Metal and the Phosphine. Some nickel (0) derivatives with tertiary aromatic chelating diphosphines have been obtained by reaction of metallic nickel with these ligands 43) and, similarly, the palladium (0) derivative of o-C6H4(PEt2)2 was obtained from the metal (44)-... 

Because of an increasing demand for these products in the pharmaceutical industry, a number of companies have paid special interest to the synthesis of profenes [32] such as ibuprofen, naproxen, ketoprofen and others from 1-arylethanol derivatives. Catalysts used for this transformation are palladium-phosphine complexes in concentrated hydrochloric acid, and to a lesser extent nickel-phosphine complexes in the presence of alkyl iodides or rhodium salts (cf. Section 2.9). 

Tom and coworkers published three new types of phosphines derived from diarylsul-fones, tritylimidazole or 2-bromobenzophenone (Figure 13). Their activity in palladium-catalyzed amination of aryl bromides is not general, but they do catalyze the coupling of certain substrates. For example, the coupling of morpholine with l-bromo-4-nitrobenzene (97% with 47), 4-bromo-f-butylbenzene (81% with 48) and 4-bromoanisole (96% with 49) was achieved in high yields160. 

More recently, Bergbreiter et al. have used palladium complexes associated with phosphines derived from poly(AT-isopropyl)acrylamide-c-(Ar-acryloxysuc-... 

A palladium catalyst derived from this polymeric phosphine gave yields almost identical with its homogeneous counterpart in Reaction 5.32. There was no decrease in activity after five cycles of use.132... 

Asymmetric palladium-catalyzed alkylation of various allylic acetates occurred in water or in an aqueous/organic biphasic medium, using as ligands phosphines derived from carbohydrates [29], amphiphilic resin-supported MOP and P,N-chelating ligands [30, 31], or BINAP in the presence of surfactants [32] enantio-selectivities up to 85%, 98%, and 92% have been obtained in the alkylation of 1,3-diphenyl-2-propenyl acetate, respectively. 

Ackermann has shown that palladium complexes derived from heteroatom-substituted secondary phosphine oxides are efficient for couplings of siloxanes and activated aryl chlorides (Equation 2.53) [53]. 

Palladium complexes derived from stericaUy encumbered electron-rich phosphines such as QPhos (362) are well-suited catalysts for the reaction of aryl bromides with zinc enolates of esters [259] or amides [260] and also of aryl chlorides with the Reformatsky reagents [261]. As exemplified with the efficient formation of 361 (Scheme 4.82), only mono-arylation is observed, and the... 

Well-defined palladium complexes are interesting from an academic point of view. In 2013, Shi, Cao and their co-workers prepared a well-defined fer-rocenyl functionalized NHC-palladium complex and applied it as an efficient catalyst for Larock heteroannulation. 2,3-Disubstituted indoles were isolated in good yields (69-90%) with high regioselectivity from the reactions between 2-iodoanilines or 2-bromoanilines and their derivatives with various internal alkynes (Scheme 2.98). The reactions occur in a broad scope and with a high tolerance of functional groups. NHC-palladium complexes could be excellent candidates to replace expensive palladium-phosphine complexes for Larock indole catalysis. 

---