Palladium complexes phosphino

In 2005, Carretero et al. reported a second example of chiral catalysts based on S/P-coordination employed in the catalysis of the enantioselective Diels-Alder reaction, namely palladium complexes of chiral planar l-phosphino-2-sulfenylferrocenes (Fesulphos). This new family of chiral ligands afforded, in the presence of PdCl2, high enantioselectivities of up to 95% ee, in the asymmetric Diels-Alder reaction of cyclopentadiene with A-acryloyl-l,3-oxazolidin-2-one (Scheme 5.17). The S/P-bidentate character of the Fesulphos ligands has been proved by X-ray diffraction analysis of several metal complexes. When the reaction was performed in the presence of the corresponding copper-chelates, a lower and opposite enantioselectivity was obtained. This difference of results was explained by the geometry of the palladium (square-planar) and copper (tetrahedral) complexes. 

Helmchen and coworkers employed a,co-amino-1,3-dienes as substrates [51]. By using palladium complexes with chiral phosphino-oxazolines L as catalysts, an enantiomeric excess of up to 80 % was achieved. In a typical experiment, a suspension of Pd(OAc)2, the chiral ligand L, the aminodiene 6/1-90 and an aryltriflate in dimethylformamide (DMF) was heated at 100 °C for 10 days. Via the chiral palladium complex 6/1-91, the resulting cyclic amine derivative 6/1-92 was obtained in 47% yield and 80% ee (Scheme 6/1.23). Using aryliodides the reaction time is shorter, and the yield higher (61 %), but the enantiomeric excess is lower (67% ee). With BINAP as a chiral ligand for the Pd°-catalyzed transformation of 6/1-90 and aryliodide, an ee-value of only 12% was obtained. 

Dinuclear palladium complexes catalyze m-hydroarylation of alkynes with arenes.56 The reaction of 3-hexyne with benzene in the presence of a dinulear palladium complex Pd2R2(M-OH)(//-dpfam) [dpfam = j/V,Ar -bis[2-(diphenyl-phosphino)phenyl]formamidinate, R=/>-Tol] and tri(/z-butyl)borane at 100 °C for 4h affords ( )-3-phenyl-3-hexene quantitatively (Equation (53)). The hydroarylation of 3-hexyne with monosubstituted benzenes ( )-3-aryl-3-hexenes with a 2 1 ratio of the meta- and ra -isomers. This regioselectivity is different from that of the hydroarylation of diphenylacetylene catalyzed by Rh4(GO)12.57... 

Heck reactions have also been used by Helmchen et al. for a two-component domino process of a,co-amino-1,3-dienes.1721 By using palladium complexes with chiral phosphino-oxazolines as catalysts an enantiomeric excess of up to 80 % is achieved. In a... 

Tests made in a batch-wise system showed that Go-5 had a lower activity than the corresponding monomeric phosphino ester palladium complex. Although less active, the metallodendrimer Go-5 displayed higher stability... 

Figure 3.91 Decomposition of a palladium II) phosphino functionalised NHC complex with...

The two dimeric complexes illustrated in Scheme 7-36 are related to the diphenyl-phosphino-palladium complexes above described. 

Methods for the synthesis of C-functionalised arylphosphines based on the direet introduetion of phosphino groups into aryl halides or tosylates, eatalysed by a variety of metals, have eontinued to develop. The reaetions of seeondary phosphines (and seeondary phosphine oxides) with bromo- or iodo-arenes, eatalysed by palladium aeetate or other palladium complexes, have been used... 

Pozzi, Sinou, and co-workers prepared a fluorous chiral phosphine, (R)-2- bis[4-(1 H,1 H-perfluorooctyloxy)phenyl]phosphino -2 -(l H,1 H-perfluorooctyloxy)-l, 1 -binaphthyl (F content = 52%, partition coefficient n-perfluorooctane/toluene = 0.23, n-perfluorooctane/CHjOH = 7.42) and used for a chiral ligand of palladium complex in an asymmetric aUyHc alkylation of 1,3-diphenylprop-2-enyl acetate [8]. The reaction was carried out at room temperature in BTF or toluene and gave the corresponding product in 99% and 88% chemical yields and 81% ee and 87% ee, respectively after the nonfluorous MOP complex gave the product in 95% yield and 99% ee in toluene at 0 °C [9]) [Eq. (1)]. When toluene was used as a solvent, the simple extraction of the reaction mixture with n-perfluorooctane (twice) allowed the complete removal of the ligand and of the palladium complex. However, the recovered palladium complex did not have catalytic activity for the reachon. 

Baceiredo and Bertrand combined the two privileged coordination moieties to an (amino)(phosphino)carbene ligand [117], after which the palladium complex formed by reaction of this ligand and PdCl2(cod) was isolated and structurally characterized. Whilst the results of the amination experiments were not... 

Chatt J, Hitchcock PB, Pidcock A, Warrens CP, Dixon KR (1982) Synthesis and P n.m.r. spectroscopy of platinum and palladium complexes containing side-bonded diphenyldi phosphene. The X-ray crystal and molecular structure of [Pd(PhP = PPh) bis(diphenyl-phosphino)ethane ]. J Chem Soc Chem Commun 932-933... 

Garcia Mancheno O, Gomez Arrayas R, Carretero J-C (2005) Palladium complexes of chiral planar l-phosphino-2-sulfenylferrocenes as efflcient catalysts in enantioselective Diels-Alder reactions. Organometallics 24 557-561... 

The new arsino(phosphino)methanes with bulky substituents at the two donor centers can behave both as chelating and bridging ligands toward palladium(II). Besides neutral and mono- as well as di-nuclear cationic compounds, in which these ligands are bonded in a chelating fashion, a di-nuclear complex of the A-frame type could also be generated (see Scheme 5).396... 

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