Reactions of Phosphoric Acids and their Derivatives

The base-catalysed rearrangement of the alkyl phosphates, particularly those possessing secondary alkyl groups, (50), into (l-hydroxyalkyl)phosphonic esters 

Many alkyl diphenyl esters of phosphoric acid were examined in a study of the rearrangements of compounds of the general form (52) into (53) brought about under free radical conditions by the action of tributylstannane and AIBN. Typical of the examples studied is (54) (X = H) which, under normal circum- 

The interaction of secondary alcohols with either triphenyl phosphate or diphenyl phosphorochloridate under conditions of thermolysis provides alkenes through effective dehydration. Mixtures of dialkyl hydrogenphosphates and alkyl dihydrogenphosphates (generated from an alcohol and P4O10) act as alkylating agents for alcohols and phenols.  

Mixed phosphoric-carboxylic anhydrides are obtainable from carboxylic anhydrides and trimethylsilyl phosphorus(V) esters.  

Study of the photolytic behaviour of triaryl phosphates has been further extended new model substrates examined include tri-l-naphthalenyl, tri-9-anthracenyl, and tri-8-quinolinyl phosphates, together with some of their methoxy derivatives and analogous dialkyl aryl and alkyl diaryl esters. Noted reactions include aryl migrations with the formation of, for example, l-[2-(l-naphthalenyl)-naphthalenyl] phosphate, in substantial amounts, together with appropriate biaryls. A preliminary report describes the photolysis of methyl alkenyl aryl phosphates (58) which undergo transformation along more than one pathway. The isolated products from (58) (R = OMe, = Me) were (60), 

Many further examples of reactions in which phosphate anions act as leaving groups have been reported. Palladium-catalysed reactions of cyclic ketene acetal phosphates, e.g. 64, are reported to offer advantages over the corresponding 

Diferrocenyldithiadiphosphetane disulfide (95) has been reported to react with bicyclic dienes to form four- and six-membered phosphorus and sulfur-containing rings which are characterised by X-ray crystallography in several cases. Phosphate and thiophosphate triesters react with a-diazoacetates in the presence of BFa.etherate as a catalyst to give, respectively, O-alkoxycarbonylmethyl phosphates 96 and S-alkoxycarbonylmethyl phosphates.  

The X-ray crystal structural analysis of the optically active 2-chloro-l,3,2-diaza-phospholidine 2-oxide 97 has been reported. Reactions of 97 with chiral amino alcohols lead to ring opening and formation of the 1,3,2- 

Reports which have clear applications in DNA hydrolysis include one of a dinuclear lanthanum(III) complex that catalyses phosphate diester hydrolysis to give unprecidented rates of reaction and one describing the preparation of two new dinuclear bisimidazolyl-Cu(II) calixarenes and an investigation of these complexes as metalloenzyme models for phosphate diester cleavage. The importance of tuning microenvironments when designing synthetic nucleases is illustrated by a report that intramolecular trans-esterification of 2-hydroxy-propyl-4-nitrophenyl phosphate (84) is up to 5000 times faster in organic solvents than in water/  

A detailed NMR study has been reported of the hydrolysis, in aqueous solution at specific pH values, of the alkylating anti-tumour agent ifosfamide (85), and its metabolites (86), (87), and (88) The first step in each case is ring-opening by hydrolysis of the endo-cyclic P-N bond. In kinetic studies aimed at modelling enzyme-mediated formation of high-energy phosphates, the 

Tetrakis(l,T-binaphthyl-2,2 -diyl phosphate) complexes (119) are reported to be much more effective catalysts than the more commonly used carboxylate complexes for enantioselective intramolecular, tandem, carbonyl ylide forma-tion/cycloaddition of a-diazo- -keto esters. The ring-opening reactions of epoxides with diphenyl phosphorazidate (120) have been investigated. A wide range of epoxide substrates have been studied and the products, (121) or (122), depend on the substrate structure. The microbial hydroxylation of novel phos- 

---

Reactions of Phosphoric Acids and Their Derivatives. - Numerous investigations of phosphate ester hydrolysis continue to be reported. The hydrolysis between 1.5 < pH < 4 of five- and six-membered cyclic phosphoramides (71) has been followed by UV and NMR spectroscopy. Small differences in hydrolysis reactivity for n = 5 and n = 6 constitutes evidence for syn lone pair catalysis. The product ratios from the hydrolysis shows that in the five-membered rings the main product is the one produced by endocyclic cleavage meanwhile, in the six- membered cyclic phosphoramide the kinetic product is the one produced by exocyclic cleavage. The syn orientation of two electron pairs on nitrogen stabilizes the transition state of water approach to the phosphoramides by ca. 3 kcal/moN when compared to the orthogonal attack. (Scheme 12). ... 

Reactions of Phosphoric Acids and their Derivatives.- Addition of alcohols (ROH) to diethyl [2,2-difluoro-l-(trifluoromethyl)vinyl] phosphate yields the ether esters (64). Other fluorovinyl phosphates (65 R = F or CF, R = hexyl, cyclohexyl, or Ph) are cleaved by LiAlH /CuBr or by LiAlH /Br2 in THF at -78° to give the ketones (66) the same esters are also cleaved by... 

Reactions of Phosphoric Acids and their Derivatives. - The rearrangement of [(trimethylsilyl)methyl] phosphates to their ethyldimethylsilyl isomers is already known the mechanism of the process has now been examined in more detail and is thought to involve attack by phosphoryl oxygen at the silicon atom with migration of an alkyl group as indicated in Scheme 2. Diphenyl... 

In this year, a subsection concerning use of chiral phosphoric acids as catalysts in various chemical reactions, introduced in 2009 for the first time, has been maintained and expanded with new categories due to further, rapid progress in this area. In the subsection reactions of phosphoric acids and their derivatives, total syntheses of valuable, biologically active compounds have been presented in the literature of the review period, among these were... 

Synthesis of Phosphoric Acids and their Derivatives. - Among various approaches to phosphate esters the phosphorylation of phenols with dialkyl cyanophosphonate and the synthesis of triaryl phosphates under phase-transfer conditions are worthy of mention. Mixed trialkyl phosphates are also reported to be formed by brief cathodic electrolysis of the reaction of dialkyl phosphonates with aromatic aldehydes and ketones, presumably by rearrangement of the initial a-hydroxy compounds. Further reports have appeared of the generation of metaphosphates by various methods. The synthesis of analogues 1 of famesyl pyrophosphate which incorporate photoactive esters has been reported both compounds are competitive inhibitors of farnesyl transferase. 

Synthesis of Phosphoric Acids and their Derivatives.-New approaches to the preparation of dialkyl phosphorofluoridates include the treatment of a vinyl phosphate, e.g.,(l), or an irninophosphace, e.g.,(2), with triethylamine tris(hydrogen fluoride) when the alkyl group consists of a suitably protected nucleoside, the reaction between mono(crimethylsilyl) phosphite in pyridine and sulphuryl chloride fluoride at -30° has been successfully explored. Dibenzyl phosphorofluorldate, hitherto unreported, has been obtained from tecrabenzyl diphosphate and caesium fluoride, and also from the reaction between dibenzyl hydrogen phosphate and 2-fluoro-N-methylpyridinlum tosylate. ... 

Synthesis of Phosphoric Acids and their Derivatives.—Cyclic phosphoric acids (15) possessing 6-, 7-, or 8-membered rings are conveniently prepared by means of the reactions outlined in Scheme 1. ... 

In this subsection synthesis, reactions and biological aspects of phosphorus acids and their derivatives of the general formula (R0)2P(0)0R, (RO)2-P(NR )0R (R0)2P(S)SR (R0)2P(0)SR (R0)2P(0)NR r (R2N)2P(Se)NR 2 are described. Two subsubsections have been added concerning miscellaneous applications other than biological and use of phosphoric acids and their derivatives as catalysts. 

There has been only one change of author since last year. We welcome Dr C. Bedford as author of Reactions of Carboxylic, Phosphoric and Sulfonic Acids and their Derivatives. He replaces Dr W.J. Spillane, whose major contribution to the series, through provision of expert reviews since 1983, we wish to acknowledge. 

Reactions of Carboxylic, Phosphoric and Sulfonic Acids and their Derivatives... 

---