Carbon-phosphorus bonds cleavage

Cook AM, CG Daughton, M Alexander (1979) Benzene from bacterial cleavage of the carbon-phosphorus bond of phenylphosphonates. Biochem J 184 453-455. 

Chen C-M, Q-Z Zhuang, Z Zhu, BL Wanner, CT Walsh (1990) Molecuar biology of carbon-phosphorus bond cleavage Cloning and sequencing of the phn (psiD) genes involved in alkylphosphonate uptake and C-P lyase activity in Escherichia coli. J Biol Chem 265 4461-4471. 

La Nauze JM, H Rosenberg, DC Shaw (1970) The enzymatic cleavage of the carbon-phosphorus bond purification and properties of phosphonatase. Biochim Biophys Acta 212 332-350. 

Wanner BL (1994) Molecular genetics of carbon-phosphorus bond cleavage in bacteria. Biodegradation 5 175-184. 

The decomposition of nitrilotrimethylenetriphosphonic acid in acid solution has been studied. At 125-175° and pH 1.5, carbon-phosphorus bond cleavage occurs, but in 5M HC1 aq. carbon-nitrogen fission becomes important.1" ... 

Scheme 5.2. Demonstration of retention of configuration during electrochemical cleavage of the carbon-phosphorus bond, Ref. [49. ...

In continuation of our efforts to explore the utility of the SAMP/RAMP hydra-zone methodology, we developed the first asymmetric synthesis of a-phosphino ketones via formation of a carbon-phosphorus bond in the a-position to the carbonyl group [70]. The key step of this asymmetric C—P bond formation is the electrophilic phosphinylation of the ketone SAMP hydrazone 87, giving rise to the borane-adduct of the phosphino hydrazone 88 with excellent diastereoselectiv-ity (de = 95-98%). Since these phosphane-borane adducts are stable with respect to oxidation, the chemoselective cleavage of the chiral auxiliary by ozonolysis leading to the a-phosphino ketones (R)-89 could be accomplished with virtually no racemization. Using RAMP as a chiral auxiliary, the synthesis of the enantiomer (S)-89 was possible (Scheme 1.1.25). 

The o-acylaminobenzylphosphonium salts are available from two ways (1) reduction of o-nitrobenzylphosphonium saltZ with zinc in hydrobromic acid-ethanol (yield 95%). The reductive cleavage of the carbon-phosphorus bond can be avoided by using only two equivalents of reagent (2) condensation of o-aminobenzyl alcohols with triphenylphosphine and hydrobromic acid. 

The cleavage of carbon phosphorus bonds in phosphoryl compounds is another matter for consideration. Once a carbon-phosphorus bond is generated, usually it is extremely difficult to cleave it without major damage to the remainder of the molecule. However, phosphonate and phosphinate esters, as well as phosphine oxides, in which a hydroxyl or carbonyl group is present at the carbon directly attached to phosphorus are subject to facile cleavage of the carbon-phosphorus bond. 

Reactions with Cleavage of One Carbon-Phosphorus Bond... 

Reactions with Cleavage of Two Carbon-Phosphorus Bonds... 

Denmark, S. E., Dorow, R. L. Stereospecific cleavage of carbon-phosphorus bonds stereochemical course of the phosphinoyl curtius (Harger) reaction. Chirality 2002,14, 241-257. 

The relatively stable carbon-phosphorus bond is resistant to cleavage by phosgene in a way that is similar to a carbon-carbon bond in a hydrocarbon chain. The phosphorus atom, in its formal oxidation state of +3 in an organic compound, however, may react by virtue of its unshared electron pair. 

It has been known for many years that transition metals catalyze reactions of coordinated phosphines (2). Known reactions of phosphines as ligands include carbon-hydrogen lx)nd cleavage (cyclometalation), as well as direct carbon-phosphorus bond cleavage. Such metal-catalyzed reactions of phosphines lead to formation of new metal complexes which can affect catalyst properties. A known example is the reaction of triphenylphosphine to propyldiphenylphosphine during the rhodium-catalyzed propylene hydrogenation or hydroformylation (5). 

Tertiary phosphines substituted at the -carbon by electronegative groups, e.g. (56), react with boron trihalides to give products derived from carbon-phosphorus bond cleavage. Phosphines containing only hydrocarbon groups do not react. 

The t-butyl ethers (210) are the major products of photolysis of the phosphate esters (211) in t-butanola benzyl cation-phosphate ion pair is thought to be involved in this conversion. In contrast, initial carbon-phosphorus bond cleavage is responsible... 

The biotransformation of methyl phenyl phosphonate to benzene by K. pneumoniae (Cook et al. 1979) (Figure 4.31a). Further examples of the cleavage of the carbon-phosphorus bond by other members of the Enterobacteriaeae and a discussion of the metabolism of phosphonates are given in Chapter 6, Section 6.9.4. 

With tris(trimethylsilyl)phosphite, regiospecific and irreversible adduct formation with 2( H)-pyrimidinones gives 3,4-dihydro-4-phosphonic acid silyl esters (317) which furnish the phosphonic acid (318) on treatment with methanol (Scheme 53). The regiochemistry is attributed to the bulkiness of the phosphite reagent. The carbon-phosphorus bond resisted cleavage by TFA <87ACS(B)448>. 

A few reports do exist on the cleavage of carbon-phosphorus bonds in an aqueous medium under alkaline and acidic conditions (11,34). Oxidation is also an obvious side reaction, especially with the trialkyl-phosphines (22,27). However, separation of phosphines from phosphine oxides is possible by distillation or gas chromatography (10, 50,71). 

Pentaarylphosphoranes also undergo cleavage of carbon-phosphorus bonds in aqueous acid or base, as well as halogenolysis. In the latter instance, a quaternary phospho-nium salt is generated along with the haloaromatic product (equation 46). ... 

Instability in the supposedly stable phosphorus-carbon bond displays itself not only in unfortunate ways, leading as it does to side reactions and the formation, in synthesis, of unwanted by-products, but also in a constructive manner, forming the basis of reaction sequences of outstanding value in synthesis, as for example in alkene-forming reactions. Instability is an inherent property of (a-hydroxyalkyl)phosphonic acids which manifests itself in phosphorus-carbon bond cleavage as a result of the action of heat or of alkali, and which can lead either to dissociation into precursors or to rearrangement to phosphates (a-oxoalkyl)phosphonic derivatives are susceptible to attack by nucleophiles, a process which also results in carbon-phosphorus bond fission. 

The presence of electron-withdrawing groups positioned on an aromatic nucleus bonded directly to phosphorus can be a source of instability in the phosphorus-carbon bond. This situation is found particularly in (4-nitrophenyl)phosphonic acids. (2-Methoxy-4-nitrophenyl)phosphonic acid can be demethylated in 40% HBr, but cleavage of the carbon-phosphorus bond becomes more pronounced in a reaction with 48% HBr moreover, hydrogenation of the same acid over Raney nickel yields the expected (4-amino-2-methoxyphenyl)phosphonic acid, but a similar reduction of (2-hydroxy-4-nitrophenyl)-phosphonic ac id results in the separation of 3-aminophenol. These and other, similar, reactions have been surveyed by Freedman and Doak ". ... 

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