Triarylphosphine oxides

Intermediate 134 could then collapse to 136, which upon loss of the trialkyl- or triarylphosphine oxide would give the enamine (137). The conversion of 134 to 137 is probably best viewed as a concerted process. 

Finally, Cristau and coworkers have reported on a quite efficient preparation of triphenylphosphine oxide (Figure 2.13) by a similar addition-elimination reaction of red phosphorus with iodobenzene in the presence of a Lewis acid catalyst followed by oxidation of an intermediate tetraarylphosphonium salt.42 This approach holds the potential for the preparation of a variety of triarylphosphine oxides without proceeding through the normally used Grignard reagent. Of course, a variety of approaches is available for the efficient reduction of phosphine oxides and quaternary phosphonium salts to the parent phosphine, including the use of lithium aluminum hydride,43 meth-ylpolysiloxane,44 trichlorosilane,45 and hexachlorodisilane.46... 

Furukawa, N. Ogawa, S. Matsumura, K. Fuji-hara, H. Extremely facile ligand-exchange and disproportionation reactions of diaryl sulfoxides, selenoxides, and triarylphosphine oxides with organolithium and Grignard reagents. 

Trialkyl and triarylphosphine oxides are also prepared by oxidation of trialkyl and triarylphosphine sulfides and selenides (equation 540) [1007, 1194]. 

D. The calculations confirm that the negative end of the dipole is towards phosphorus. - The calculated dipole moments of phosphole (1.9 D) and pyrrole (2.0 D) are similar, and, unlike furan, the positive ends of the dipoles are towards the heteroatoms. Dipole moments have been used, in combination with results from other methods of study, to estimate the preferred conformations of the dichloride (179), of the phosphites (180), and of triarylphosphine oxides. The use of dipole moments to aid stereochemical studies of compounds has been reviewed. Additive polarizability parameters should not be used in the calculations, and it has been recommended that data should be obtained from model compounds containing identical environments for the phosphorus atoms. The sensitivity of bond moments to structural changes has been studied perfluoroalkyl groups lower the phosphoryl bond moment, and the P—N bond moment is very sensitive to the valence state of the phosphorus atom. The conformational analyses of phospho-nates, phosphonamides, silyl phosphates, and a number of dioxaphosphori-nans (181) - have been reported. The P—Se bond moment has been estimated to be 1.24 D. The zwitterionic structure (182) was identified by its high dipole... 

The triarylphosphine oxides are sohds, and those which do not contain nitro- or amino-groups substituted in the benzene ring yield double salts with many metal chlorides, such derivatives ha dng well-defined crystalline forms. 

Triarylphosphine oxide moieties can be incorporated directly in the backbone of the PA. ° The polar group enhances the solubility of the PAs and imparts flame retardancy. 

Triarylphosphine oxides are prepared by coupling aryl halides or triflates with diphenylphosphine oxide (36), and they are reduced to triarylphosphine with HSiCls. Selective monophosphination of 2, 2 -bis-triflate of binaphthol (35) with diphenylphosphine oxide occurred to give the optically active phosphine oxide (37) using DPPB or DPPP. No bis-substitution was observed [6,7], The phosphine oxide 37 can be converted to the phosphine by treatment with HSiCls and an amine. Various optically active monodentate phosphines such as MeO-MOP (VI-12) are prepared from 37 via 38. On the other hand, bis-substitution of 35 takes place to afford the bis-phosphine when NiCl2(dppe) is utilized as a catalyst, and the reaction is used for the preparation of BINAP (XV-1) [8]. 

Reaction of 2-bromobenzaldehyde (39) with diarylphosphine oxide using Pd(OAc)2 and DPPP afforded the mixed triarylphosphine oxide 40, which was converted to the chiral phosphine ligand 40a [9]. 

This reaction can be used to synthesize different trialkyl- or triarylphosphine oxides. 

Several triarylphosphine oxides and related compounds have been reported. The tri-o-tolylphosphine, phosphine oxide, and phosphine selenide structures have been determined in order to study the rotational isomerism of the P-C(aryl) bonds. The geometry at the phosphorus is normal, with P-C... 

A triarylphosphine oxide type monomer was prepared by the Grignard reaction of Ph2P(0)Cl, followed by dinitration and double reduction steps (Scheme 46). ... 

Disproportionation complexes are formed by thermal reaction of either trialkyl or triarylphosphine oxides with Fe(CO)s in polar or nonpolar solvents (H. Alper and E. C. H. Keung, unpublished). Irradiation of PhaPO and Fe(CO)5 at 80° gave similar products (Hieber and Lipp, 1959). Treatment of phosphineimines with Fe(CO)5 in THF results in a unique deoxygenation of a carbonyl group of the metal carbonyl to give PI13PO and isonitrile complexes (Alper and Partis, 1972). 

Stereochemical aspects of the Wittig reaction have been investigated by NMR spectroscopy of the oxaphosphetane intermediates. User-friendly silanes, such as tetramethyldisiloxane and poly(methylhydrosilane) were applied in the deojygenation of different phosphine oxides. Optically active 1-all l- and l-atyl-3-phospholene oxides were also reduced by silanes, and the resulting phospholenes were utilized as P-ligands in Pt complexes.A novel deojygenation of triarylphosphine oxides was elaborated using oxalyl chloride and a Hantzsch ester (Scheme 59). ... 

Triarylphosphine oxide containing polymers have recently received considerable attention due to their enhanced thermal / oxidative and ignition resistant... 

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