Catalysts phosphines

By the use of base catalysts phosphine and phenylphosphine for example can be cyanoethylated. Acrylonitrile and phosphine react together at room temperature in the presence of aqueous potassium hydroxide solution to give, depending on the reaction conditions, primary, secondary and tertiary 2-cyano-ethyl-phosphines... 

This quite remarkable process is based on simultaneous use of an insoluble lipase (ChiroCLEC, 10, Scheme 12.3) and vinyl pivaloate for conversion of one enantiomer (R) of the substrate alcohol and of the solid-phase-bound anhydride 11 in combination with the phosphine 5a for the conversion of the other enantiomer (S). This system meets the requirement that the soluble acyl donor (vinyl pivaloate) does not cross-react with the soluble catalyst (phosphine 5a). After completion of the reaction the solid-phase-bound (S) enantiomer can easily be separated from the (R) product which remains in solution. As summarized in Scheme 12.3, this three-phase system affords remarkable yields and enantiomeric purity of the acy-lated alcohols [13]. 

Phosphine is used as an insecticide for the fumigation of grains, animal feed, and leaf-stored tobacco, and as a rodenticide. Phosphine is also used as an intermediate in the synthesis of flame retardants for cotton fabrics, as a doping agent for -type semiconductors, as a polymerization initiator, and as a condensation catalyst. Phosphine is used in the semiconductor industry to introduce phosphorus into silicon crystals. 

Because homogeneous catalysts are typically organotransition metal complexes, it is relatively easy to modify these compounds in order to increase selectivity. As we shall see, phosphines appear commonly as ligands in homogeneous catalysts. Phosphines offer a wide variety of stereoelectronic properties that can substantially influence the course of a catalyzed reaction. 

Table 2 Relative rates of aryl group interchange between triphenylphosphine and tris-para-tolylphosphine cat yzed by group 8 transition metals. Reaction conditions 1000 ppm of metal catalyst phosphine metal mole ratio = 20 100 psi ofH2 C3H6(l l)...

Unmodified cobalt catalyst Phosphine modified cobalt catalyst Phosphine modified rhodium catalyst... 

Ozawa conditions Herrmann s catalyst, phosphine ligand CS2CO3, THF, 125 C, 24 h Fagnon conditions Pd(OAc)2, PivOH, K2CO3 DMAc, 95°C, 72 h... 

Catalyst Pd(PPh3)4 Pd(PPh3)4 or Pd(II) catalyst/Phosphine ligand Pd(PPh3)4... 

Polymerizations using Phosphorus-Based Catalysts Phosphines and Phosphazenes 86... 

The synthesis of bicyclic pyrrolidines has also been reported by the same group via the reaction of tethered iV-substituted cyclopentenyl amine with aryl bromide in the presence of the Pd2(dba)3 catalyst, phosphine ligand, and NaOf-Bu as the base (Scheme 40.6). " ... 

Carbon nucleophiles reactions facilitated by Lewis acid/base bifunctional catalysts Phosphine-boronates (354) have been developed as bifiinctional organocatalysts (combining a Lewis base and Lewis acid in the same molecule) for the Michael addition of malonates R CH(C02R )2 to CH2=CHCOMe. The -phosphonium enolate (355)... 

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