P,S ligands

A variety of enantiopure or enantiomerically enriched phosphines, diphosphines, phosphites, diphosphites, phosphinephosphites, thiols, dithiols, P,N-ligands, and P,S-ligands have been developed as chiral modifiers of rhodium and platinum catalysts [1-7], Representative chiral ligands discussed in this chapter are shown in Figure 7.1. 

Evans showed that his P,S-ligand 36 was also efficient for the monoalkylation of cis- 1,4-diacetoxycyclopentene 76. Reaction of dimethyl malonate/BSA gave 77 in 85% yield and 96% ee (Eq. 6) [95]. The same reaction and the intramolecular cyclization of a biscarbamate has also been reported using a polymer-supported Trost-type catalyst with excellent results [166,167]. 

Scheme 8 Technetium nitrido complexes with bidentate mixed P,S ligands...

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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