Phosphine oxides from phosphorus

Brown and co-workers synthesized optically active phosphine oxides from phosphorus trichloride by sequential addition of nucleophiles to chiral oxazaphospholidine [Eq. (24)]. The key step in this synthesis is control of the stereochemistry of the oxazaphospholidine, since the stereochemistry from the other steps is well characterized. The overall result is a greater than 94% e.e. 

Gusarova, N.K., Shaikhudinova, S.I., Reutskaya, A.M., Tartarinova, A.A., and Trofimov, B.A., One-step synthesis of unsymmetrical tertiary phosphine oxides from red phosphorus and organyl halides, Russ. Chem. Bull., 49, 1320, 2000. 

Phosphinous halides can be prepared from secondary phosphine oxides and phosphorus trichloride. The starting secondary phosphine oxides are easy to handle and can be prepared by treating readily available diethyl or dibutylphos-phite with an organometallic reagent.33... 

If a nucleophilic addition at a carbonyl or imine carbon occurs, the product is still a phosphinate (from a phosphonous ester) or a phosphine oxide (from a phosphinous ester), but the reaction is commonly referred to as an Abramov or Pudovik reaction. An example of the Pudovik reaction is shown below (equation 16). Addition of the phosphorus nucleophile to the /3-carbon atom of an a, /3-unsaturated substrate (Michael addition) is commonly referred to as a hydrophosphinylation reaction. ... 

The reaction which uses the phosphorus ylide also produces31 35,77 highly stereo-selectively 1 -heterosubstituted-1 -vinylcyclopropanes, but now the (Z)stereoisomers are the major ones (Schemes 61, 62 a, 63 a). It is well-known that in the Wittig reaction the betaines which lead to the (Z)-disubstituted olefins are formed under kinetically controlled conditions and that any feature which favours the elimination of triphenyl-phosphine oxide from these betaines should increase the amount of the (Z)stereoiso-... 

A second exception occurs with the elimination of phosphine oxides from oxaphosphetanes. The pentacoordinate phosphorus serves as the electron source in an internal elimination of the oxygen bound to phosphorus. 

Triethyl Phosphine Oxide from Ethyl Iodide and Phosphorus (3)... 

The Michael-Arbuzov rearrangement is a basic reaction for the preparation of 4-coordinate species including phosphine oxides from 3-coordinate phosphorus esters, such as phosphinous esters. In most cases, the reaction requires a prolonged heating above 100 °C. Odinets et al. have now succeeded in carr5nng out the Arbuzov-reaction of ethyl diphenylphosphinite with a variety of alkyl halides in ionic liquids at or below 110 °C in short reaction times, mostly within half an hour. The best ionic liquid was l-hexyl-3-methylimidazolium bromide (Scheme 2). The recovered [hmim]Br could be recycled at least five times without a decrease in activity. 

Sodium dihydridobis-(2-methoxyethoxo)aluminate Formation of phosphorus-carbon bonds Phosphine oxides from phosphinic acid esters... 

Although of limited success, this Ni-catalysed coupling strategy builds on a previous report of the successful, direct synthesis of poly(4,4 -diphenylphenyl-phosphine oxide) (70c) from bis(p-chlorophenyl)-phenylphosphine oxide (71) (Scheme 21) [66]. The white soluble material (70c) (Aj ax 280 nm) was found to have a single phosphorus environment by NMR spectroscopy, a comparatively high molecular weight (Mn= 15,300) together with a low molecular... 

B. By Hydrolysis Reactions.—Details have appeared of the synthesis of dibenzophosphorin oxides (15) from 5-alkyldibenzophospholes, by reaction with methyl propiolate in the presence of water, and of confirmatory syntheses from phosphinic acid chlorides, as shown below. Evidence for the suggested mechanism of the ring-expansion reaction is presented. The hydrolysis of enamine phosphine oxides is an efficient, although somewhat indirect, method for the preparation of j8-ketoalkylphosphine oxides (16) [see Section 3(iii), for the preparation of enamine oxides]. Reasonable yields (48—66%) of trialkylphosphine oxides (17) have been obtained by the alkaline hydrolysis of the products from the pyrolysis at 220 °C of red phosphorus with alkyl halides, in the presence of iodine. 

D. Miscellaneous.—A further study of the reactions of diphenyl-phosphine oxide with tetracyclone has confirmed that the reaction yields the oxide (30) under mild, basic conditions, and that the reaction is thermally reversible. The displacement of halogen from phosphorus by amino-compounds has been used in the synthesis of a number of aminofluoro-phosphine oxides (31), and of A-methyl-AA-bis(dichlorophosphinyl)-amine (32). ... 

This reaction may be visualized as proceeding by nucleophilic attack of tervalent phosphorus at the carbonyl group to give an intermediate such as (15). The structure of (16) was deduced from the fact that it was hydrolysed to the known phosphine oxide (17). Methylenephosphoranes (phosphorus ylides) may also be converted into monophosphazenes by reaction with benzonitrile ... 

The phosphine oxide (10), the first reported example of a phosphorus analogue of an unsaturated 3-lactam, has been obtained from the... 

A Michael-type addition reaction of phosphine generated from red phosphorus in concentrated aqueous KOH solution has been noted to provide moderate isolable yields of pure organophosphorus products.27 For example, tris-(2-cyanoethyl)phosphine is produced in 45% isolable yield from acrylonitrile, and tris-(2-[y-pyridyl]ethyl) phosphine oxide is isolated in 40% yield from 4-vinylpyridine under these conditions. Excellent yields of the tertiary phosphine oxide, tris-(2-cyanoethyl)phosphine oxide, have been reported using white phosphorus in absolute ethanol with KOH at ice/salt-bath temperatures.28 A variety of solvent systems were examined for this reaction involving a Michael-type addition to acrylonitrile. Similarly, tris-(Z-styryl)phosphine is produced from phenylacetylene under these conditions in 55% isolated yield. It is noteworthy that this last cited reaction involves stereospecific syn- addition of the phosphine to the alkyne. 

Trofimov, B.A., Gusarova, N.K., and Brandsma, L., Generation of phosphide anions from phosphorus red and phosphine in strongly basic systems to form organylphosphines and -oxides, Phosph., Sulf. Silic., 109-110, 610, 1996. 

Similarly, monobasic forms of other trivalent phosphorus species have been used successfully in such conjugate addition processes, including monoesters of phosphonous acids375 425 426 and secondary phosphine oxides.427-429 The notable exception to the last of these species is the addition of the anion from diphenyl phosphine oxide to unsaturated aldehydes, which appears always to proceed by addition to the carbonyl carbon.427... 

In 1975, Hendrickson and Schwartzman reported a different mode of phosphorus-based hydroxyl activation using bis(phosphonium) electrophiles (R3P—O—PR3)2+. These highly reactive electrophiles are generated from the reagent combination of phosphine oxide and trifluoromethanesulfonic (triflic) anhydride [96]. Mukaiyama... 

From the product analyses of PET reactions of trivalent phosphorus compounds such as phosphines and phosphates, it is found that P reacts with nucleophiles such as water and alcohol to yield phosphine oxides and phosphates [92-95]. During a reaction of triphenylphosphines (P(CgH4-X-/ )3 with water to give phosphine oxides 0=P(C6H4-X-/ )3... 

Phosphorus-Substituted Organometallic Compounds From Phosphine Oxides... 

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