Stille phosphane ligands

Fig. 16.29. Two-component variant (upper example) and three-component variant (lower example) of Stille reactions to be used for the preparation of unsaturated ketones. The phosphane ligand in the lower example is dppf [for bis(diphenylphosphino)fer-rocene], a diphosphane the structure of this ligand can be derived from the Formulas B-D.

The selectivity to linear product is improved by using a cobalt trialkyl phosphine complex, but the major product is the corresponding alcohol. The use of rhodium triphenylphosphine hydrocarbonyl gives a still higher selectivity to linear aldehyde under milder conditions. These advantages are retained by using a water-soluble rhodium complex with sulphonated phosphane ligands, which provides a novel two-phase mode of operation (recently commercialized). ... 

While the q -bonding mode in the iron complex 3 has earlier been established crystallographically [11, 12], it is remarkable that this coordination mode is observed in a 17 electron iron(III) complex as well. Dixneuf et al. treated iron(III) chloride with magnesium and dichloride 2 in the presence of phosphane ligands and obtained the respective trimethylenemethane iron(II) complexes, which were then oxidized with silver triflate resulting in the formation of cationic trimethylenemethane complexes with the ligand still being q -coordinated [30]. Bazan et al. reported a distorted coordination to zirconium [31], and... 

Caminade and Majoral reacted phosphorus-containing dendrimers with various transition metal complexes (Fig. 7) [ 113 ]. Via phosphane, diphosphane, or P=N-P=S ligands, they were able to incorporate several metals (Pd, Pt, Rh, Au, Fe, W, Zr) either in the core or in the periphery of their dendrimers. The dendritic palladium and ruthenium complexes 7 have been introduced in Stille couplings, Knoevenagel condensations and diastereoselective Michael additions. A positive dendritic effect and high stability of dendritic Pd complexes has been observed. Separation occurred by precipitation with ether and reuse was reported. 

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