Tertiary phosphine oxides preparation

Preparation by Addition of Tertiary Phosphine Oxides to Acetylene... 

Preparation of a tertiary phosphine oxide from white... 

The lone structurally characterized imido complex is MoO(NH)Cl2(OPEtPh2)2.270 Here the oxo and imido ligands are cis to each other with Mo—0=1.66 and Mo—N = 1.70A, respectively. The N—H hydrogen has been located and the Mo—N—H angle is 157°. The orange-yellow complex was prepared by the reaction of MoOCl3 with Me3SiN3 followed by the addition of the tertiary phosphine oxide.270... 

Tambute, A., Gareil, R, Caude, M., and Rosset, R., Preparative separation of racemic tertiary phosphine oxides by chiral high-performance liquid chromatography, J. Chromatogr., 363, 81, 1986. 

A noteworthy synthetic application for the reaction of J with a,g-unsaturated phosphoryl compounds is represented by the addition involving hitherto unknown (-)-(Sp)-methylphenylvinylphosphine oxide J 2. The resulting tertiary phosphine oxides 13 with saturated carbon chains and known stereochemistry at phosphorus constitute attractive starting materials for the preparation of optically pure phosphines. The organophosphorus substrate 12 was obtained by decarbomenthoxylation of the enantiomeric ester... 

The tertiary phosphine oxides are most commonly prepared by simple oxidation of the parent phosphine with hydrogen peroxide,1 alkylation of a trihalophosphine oxide,2 or by oxidation of an appropriate phosphonium salt by moist silver(I) oxide.3 The simplest and quickest method is the peroxide oxidation of the parent phosphine. Inasmuch as appropriate syntheses... 

Tertiary phosphine oxides are also produced as significant by-products in several of the reactions of phosphines that have been noted previously, including the Wittig olefination and the conversions of alcohols to haloalkanes with triphenylphosphine as an adjunct reagent. The tertiary phosphine oxides produced in such reactions present a problem in chemical economics, as they themselves possess little chemical utility. The phosphine may be regenerated, but several steps are required, as previously noted with preparations of phosphines by reduction (see Section 3.2). 

This is a very useful route for the preparation of phosphines, especially chiral phosphines. Tertiary phosphine oxides (and sulfides) and phosphonium salts are often precursors of choice in these reduction procedures. The following sections highlight reagents and reaction conditions in forthcoming sections further examples will be given. 

The tetradentate ligand (114) was prepared in high yield (96%) by HSiCl3 reduction of the corresponding tetra(tertiary)phosphine oxide.230... 

The di-(TPPDS)239 and tri-sulfonated phosphines (116) (Scheme 8) (TPPTS)239 are also known, the latter being the most widely used water-solubilizing phosphine ligand, as of 2002. The synthesis of (116) is ostensibly similar to that of (115), although more recently it has been shown that addition of orthoboric acid to the sulfonation mixture reduces the amount of tertiary phosphine oxide side products.240 This general sulfonation procedure has been used for the preparation of various ditertiary (e.g., (117))241 242 and chiral sulfonated phosphines (e.g., (118)).241,243-245 Carboxylic acid- and carboxylate-modified phosphines (e.g., (119) and (120)) are also known.246,247... 

Notably, the only other routine method for preparing fluorinated phosphorusHII) ligands involves reduction of the corresponding tertiary phosphine oxide with HSiCl3/NEt3.91, 92... 

Interest in the preparation of tertiary phosphine oxides by this route has recently been revived by several groups of workers with the result being considerable improvement in the synthesis of tertiary phosphine oxides by this method (Kirsanov and coworkers) (for a summary see Table 1). 

The red metastable product, produced from P4 and KOH or KOEt, does not appear to be an intermediate in these, tertiary phosphine oxide syntheses, since when separately prepared, gave only minor amounts of phosphine oxide. This result indicates that the olefinic compounds must attack an earlier intermediate. The initial step was thought to involve nucleophilic attack of hydroxide ion on tetrahedral white phosphorus to give a phosphide ion that subsequently underwent a Michael-Addition to the electrophilic unsaturated compounds present (Rauhut, Bemheimer and Semsel). 

An elegant method of preparing tertiary phosphine oxides starts from elemental phosphorus and consists of using acrylonitrile or acrylamide to trap... 

This type of reaction is also observed on treatment of aliphatic aldehydes (except formaldehyde) with secondary phosphines containing electron-attracting substituents in strongly acidic solution at elevated temperature.85 It thus affords a method for preparing tertiary phosphine oxides. 

A simple method of preparing tertiary phosphine oxides is to alkylate, by alkyl halides, the metalated secondary phosphine oxides which are intermediates 425,426... 

The reactions of dialkyl phosphonates and secondary phosphine oxides with aldehydes have been used to prepare ct-hydroxyalkylphosphonates and various a-functionalized tertiary phosphine oxides. In contrast to previous reports, dialkyl phosphonates have been shown to react exothermically with benzophenone in the presence of base to give... 

The red metastable product obtained from potassium hydroxide and phosphorus does not appear to be an intermediate in this tertiary phosphine oxide synthesis. A solution of the red compound prepared separately in etlianol was not decolorized by acrylamide, and only minor amounts of the tertiary phosphine oxide were obtained. This result... 

Most assuredly the conversion of phosphoryl halides to tertiary phosphine oxides in ether does not consistently provide good yields. In contrast to the situation with phosphorus trihalide, however, the displacement sequence with phosphoryl trihalides can be of preparative value for the intermediate phosphinic halides. 

Tetravalent phosphorus halides are known to react with lithium reagents, but data is scarce. Aryllithium reagents easily displace chloride ion from phosphoryl chloride in the synthesis of tertiary phosphine oxides (143,144,174). A small quantity of the corresponding phosphinic acid (42) was isolated in the preparation of tris(p-dimethylamino-phenyl)phosphine oxide (43) (174). Choice of conditions and concentrations of reactants may well favor either the single or the double dis-... 

The Michaelis-Arbuzov-Kaehne reaction is probably the most widely used reaction in organophosphorus chemistry for the preparation not only of phosphonic and phosphinic acids (as their esters), but also of tertiary phosphine oxides. The reaction, discovered by Michaelis and Kaehne in 1898, and extensively developed by A. Arbuzov in the early years of this century, consists essentially in the interaction of phosphorus(III) acid ester with a reactive carbon-based species, generally an alkyl halide, and can be represented in very general terms as in equation 1 the reaction has been extensively reviewed... 

In order to examine the stereochemical implications in the synthesis of (largely) phosphinic acids (but also tertiary phosphine oxides), Inch and coworkers " employed carbohydrate frameworks as chiral templates. As primary substrates, the cyclic phospho-rochloridate 161 and the corresponding phosphorofluoridate 162 were prepared from methyl 1,2,3-di-O-methyl-a-D-glucopyranoside, each phosphoryl halide being obtained as a mixture of diastereoisomers, anomeric at phosphorus, and from which, in each case, the major component (thought to have an equatorial P=0 bond) was isolated. Configurations in both substrates and reaction products were assigned with the aid of proton and NMR... 

The most important reaction in this area is that which occurs between a phosphorylat-ed carbanion and an aldehyde or ketone (Scheme 24), and is most commonly used for the preparation of alkenes the modification which employs anions from tertiary phosphine oxides has been considered elsewhere ... 

Buono developed a very effective synthesis of chiral tertiary phosphine oxide starting from oxazaphospholidines. The enantiomerically pure oxazaphospholidine (Rp)-122 was prepared from PhP(NMe2)2 and (,S)-(+)-prolinol. Subsequent treatment of 122 with a variety of acids followed by hydrolysis gave both enantiomers of tert-butylphenylphosphine oxide 4c. It was found that the acid controlled the stereochemistry of the enantiomer obtained. By using acids of high acidity or Amberlyst 15 resin, (-h)-(R)-4c was obtained with good yields and enantioselec-tivities. When acids of low acidity were used, ( )-(,S)-4c was the preferred enantiomer. For example, / -toluenesulfonic acid (PTSA) afforded (R)-4c in 88% yield and 91% ee. After a recrystaUization the optically pure compound (/ )-(-t)-4c was obtained with >99% ee (Scheme 37) [67]. 

The biocatalytic desymmetrization of various C2-symmetric tertiary phosphine oxides was used for the preparation of P-chiral phosphines. Mikolajczyk et al. [183-185] studied the desymmetrization of bis-functional phosphinates and phosphine oxides. The hydrolysis of prochiral bis(methoxycarbonylmethyl) phenylphosphine oxide 274 was carried out in phosphate buffer in the presence of... 

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