Triphenylphosphine using

In 1961, Vaska and Diluzio6 showed that hydride-carbonylphosphine complexes of the formula MHX(CO)(PPh3)3 (M = Ru, Os X = Cl, Br) can be directly obtained from the metal halides and triphenylphosphine, using 2-methoxyethanol or ethylene glycol at 120-190°C. In agreement with this, in 1971, Moers7 reported the... 

The excess triphenylphosphine used in the preparation can be recovered by addition of water to the ethanol filtrates until precipitation begins. After allowing the solutions to stand 2 to 3 days in a stoppered flask, the triphenylphosphine crystallizes out. Recrystallization from ethanol and ethanol-benzene (1 1) removes triphenylphosphine oxide contaminant. 

Figure 10.6 Substituted triphenylphosphine used to solubilize [Rh(nbd)(acac)] (nbd = nor-bornadiene, acac = acetylacetonate) precursor for the synthesis of poly(phenyl acetylene) in scC02...

The same approach was applied again to the synthesis of lamellarin G trimethyl ether as shown in series b. The first three steps proceeded as expected, however the oxidation of compound 47b with manganese dioxide gave lamellarin G trimethyl ether in a disappointing yield (20%). The by-product was found to be the quinone derivative 50 formed by the preferred oxidation of the electron-rich phenolic ring. For this reason the oxidation was carried out with bromobenzene, palladium acetate and triphenylphosphine using DMF as the solvent and potassium carbonate as the base. Lamellarin G trimethyl ether was formed in 80% yield. 

If the orange crystals of [PPN] [NS3] are redissolved in acetonitrile a blue solution containing NS4 is formed. If recrystallization is necessary, acetonitrile containing PhjPS should be used as the solvent. The compound [Ph4As] [NS3] is prepared from [PI14AS] [NS4] and triphenylphosphine using a similar procedure. 

Table I. Activation of RhCl(PPh J3 Catalyzed Alkene Hydrogenations Inhibited by Triphenylphosphine Using PS-S03Ag.a J J...

Catalytic oxidation of alcohols by nickel (11) Schiff base complexes containing triphenylphosphine using NaOCl has been studied by Bhat et al. [25],... 

The most common way to construct the pyrazine ring is the condensation of 1,2-diamines with 1,2-dicarbonyl compounds followed by the aromatization. Pritchard and co-workers developed an efficient procedure to prepare pyrazines, quinoxalines and 1,2,4-triazines by such condensations <01JCS(PI)668>. Dicarbonyl component 193, prepared by coupling amino acid 192 with (terf-butoxycarbonylmethylene)triphenylphosphine using DCC-DMAP, underwent ozonolysis to give 194. Then, 194 was treated with 1,2-ethylenediamine followed by aromatization with Pd-C to give pyrazine 195 in good yield. 

The coupling with triflates often fails to proceed because of the decomposition of catalysts, precipitating palladium black at an early stage of the reaction. Presumably, triphenylphosphine used as a ligand of palladium reacts with triflates to give phospho-nium salts (Scheme 17). Addition of 1 equiv of lithium or potassium bromide is effective in preventing such decomposition of the catalyst, which is known to convert the labile cationic palladium species to organopalladium(II) bromide. 

Nucleophilic attack. Current literature underestimates the importance of nucleophilic attack as a mechanism for the catalytic decomposition of phosphines, especially with nucleophiles such as acetate, methoxy, hydroxy and hydride. For examples of nucleophihc attack at coordinated phosphorus see references [20-25]. A very facile decomposition of alkylphosphines and triphenylphosphine (using palladium acetate, one bar of hydrogen and room temperature) has been reported [20] using acetate or hydride as the nucleophile. 

Mitsunobu-type N-AIkylation of l,2,4-Dithiazolidine-3,5-dione (1). Despite its high acidity suggesting that it should be an excellent nucleophile in Mitsunobu displacement reactions of alcohols (cf. phthalimide. " ), the parent heterocycle 1 is degraded by the triphenylphosphine used in this process (see later). Similar stereoselective displacement reactions of alcohols with 1 can, however, be mediated using the readily prepared betaine reagent 7. ... 

Mechanistic studies on the quaternisation reaction were performed by Salin and co-workers. They investigated the strong acceleration of the quaternization of triphenylphosphine using maleic and ds-aconitic acids as electrophiles. The kinetic effect was rationalized on the basis of spatial structures of the generated zwitterions. 

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