Phosphines Commercially available

There are many phosphines which are commercially available. It is possible to buy triaryl phosphines with many different aromatic substituents, and phosphines containing a variety of alkyl chains are also easily available. There are about 20 different chiral phosphines commercially available. In addition, there are commercially available phosphines that are useful as synthons. A few examples are given in Table 2.1. 

Phosphites, such as triisopropyl and triphenyl phosphite, are weaker electron donors than the corresponding phosphines, but they are used in some reactions because of their greater rr-accepting ability. The cyclic phosphite trimethylol-propane phosphite (TMPP) or 4-ethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]oc-tane (8), which has a small cone angle and small steric hindrance, shows high catalytic activity in some reactions It is not commercially available, but can be prepared easily[27]. 

While certain TSILs have been developed to pull metals into the IL phase, others have been developed to keep metals in an IL phase. The use of metal complexes dissolved in IL for catalytic reactions has been one of the most fruitful areas of IL research to date. LLowever, these systems still have a tendency to leach dissolved catalyst into the co-solvents used to extract the product of the reaction from the ionic liquid. Consequently, Wasserscheid et al. have pioneered the use of TSILs based upon the dissolution into a conventional IL of metal complexes that incorporate charged phosphine ligands in their stmctures [16-18]. These metal complex ions become an integral part of the ionic medium, and remain there when the reaction products arising from their use are extracted into a co-solvent. Certain of the charged phosphine ions that form the basis of this chemistry (e.g., P(m-C6H4S03 Na )3) are commercially available, while others may be prepared by established phosphine synthetic procedures. 

From a practical point of view, it is worth noting that Heck reactions catalyzed by Pd/P( -Bu)3 do not typically require rigorously purified reagents or solvents. In addition, the palladium and phosphine sources, Pd[P(7-Bu)3]2 and Pd2(dba)3, are commercially available and can be handled in air. 

A potentially interesting development is the microwave-assisted transition-metal-free Sonogashira-type coupling reaction (Eq. 4.10). The reactions were performed in water without the use of copper(I) or a transition metal-phosphine complex. A variety of different aryl and hetero-aryl halides were reactive in water.25a The amount of palladium or copper present in the reaction system was determined to be less than 1 ppm by AAS-MS technique. However, in view of the recent reassessment of a similarly claimed transition-metal-free Suzuki-type coupling reaction, the possibility of a sub-ppm level of palladium contaminants found in commercially available sodium carbonate needs to be ruled out by a more sensitive analytical method.25 ... 

Initiator (233), and a polymer-supported analog,641 are commercially available and have found widespread use in the ring-closing metathesis (RCM) and ROMP of functionalized substrates. In addition, water-soluble variants such as (234) and (235) have been synthesized using aliphatic ionic phosphines and employed in aqueous media.642-645... 

In a related study, Srivastava and Collibee employed polymer-supported triphenyl-phosphine in palladium-catalyzed cyanations [142]. Commercially available resin-bound triphenylphosphine was admixed with palladium(II) acetate in N,N-dimethyl-formamide in order to generate the heterogeneous catalytic system. The mixture was stirred for 2 h under nitrogen atmosphere in a sealed microwave reaction vessel, to achieve complete formation of the active palladium-phosphine complex. The septum was then removed and equimolar amounts of zinc(II) cyanide and the requisite aryl halide were added. After purging with nitrogen and resealing, the vessel was transferred to the microwave reactor and irradiated at 140 °C for 30-50 min... 

Materials. The commercially available aldehydes were distilled prior to use and stored at 0°C under argon. The cyclohexene- and cyclopentene- aldehydes, and the indane aldehyde (see Table) were gifts from Professor E. Piers of this department. The Ru(TPP)(PPh3)2 complex (1) was prepared from Ru(TPP)(CO)(EtOH) and PPh3 (1,7), while Ru(TPP)(CO)(tBu2POH), was prepared from the carbonyl (ethanol) adduct by treatment with tBu2PCl (1). The phosphines were from Strem Chemicals, and the ruthenium was obtained as RuCl Ol O from Johnson, Matthey Limited. 

Commercially available tetraphenyldiphosphine adds to terminal alkynes in the presence of a radical initiator (V-40) and Ph2PCl in refluxing benzene (Equation (63)).164 After treatment of the reaction mixture with sulfur, phosphine sulfides are obtained as a mixture of stereoisomers. 

CYCLOHEXEN-l-ONE. Importantly, only 1.6 equivalents of Ag20 are required for efficient coupling. The final preparation in this series illustrates the hydrosilation of racemic 3-butyn-2-ol catalyzed by a phosphine based platinum(O) catalyst. The resultant racemic (E)-vinylsilane is then resolved with a commercially available lipase and subjected to a Johnson ortho ester Claisen rearrangement to afford [3R- AND 3S-]-(4E)-METHYL... 

Figure 15 shows the phosphine hgands in frans-Co2(CO)6(phosphine)2 investigated with the static solubihty measurement setup. They were synthesized or are commercially available. 

Example 29 iV,Ar-diisopropyl-bis[(trimethylsilyl)ethyl]phosphoroamidite have been prepared from commercial available dichloro(diisopropy-lamino)phosphine and 2-(trimethylsilyl)-ethanol [60] in 65% yield after purification by chromatography. Chao et al. have used this phosphitylating reagent in a way which is compatible with the Fmoc/tcrt-butyl strategy for the synthesis of phosphotyrosine containing peptides [61]. 

Reetz et al. (16) functionalized commercially available DAB-dendrimers with diphenylphosphine groups at the periphery (1) via a double phosphination of the amines with diphenylphosphine and formaldehyde. The transition metal complexes la-le have been prepared in which the dendrimer-N-(CH2PPh2)2 groups act as bidentate ligands. 

Mowery and DeShong used the commercially available hypervalent silicate complex TBAT as a phenylating agent for the cross-coupling reaction with allylic esters. They later reported on the use of the same organosilane for the coupling with aryl iodides and triflates and electron-deficient aryl bromides. The reactions were catalyzed by either Pd(dba)2 or [Pd(allyl)Cl]2 without the need of added phosphine ligands. 

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