Quinquevalent Phosphorus Acids

Organophosphorus Chemistry, Volume 33 The Royal Society of Chemistry, 2003 

The year s reviews cover phosphorylated indoles, phosphorus-selenium compounds, phosphoryl carbenes, phosphorus-sulphur compounds, and steroid phosphates, as well as the synthesis of phosphorus esters via oxyphosphoranes. A review on phosphonates contains many interesting applications of some of the well-tried syntheses of these as analogues of natural phosphates.  

General.— Examples of compounds possessing the hitherto unrecorded 1,2,4-azadiphosphetidine ring system have now been described. The reaction between methylenediphosphonic tetrachloride (1 R =C1) and primary aliphatic amines yields the 1,2,4-azadiphosphetidine 2,4-dioxides (2 R =Bu or PrO as mixtures o cis- and trans-isomQis the reaction fails when R is NMeg, but the compound (2 R =NMeij) may alternatively be prepared by heating compound (3).  

When iVTV-dimethylaniline is heated with phosphorus oxychloride there results a complex mixture of products, not all of them containing phosphorus those identified include the ATA/ -dimethylamino-derivatives of diphenylmethane and triphenyl-methane, as well as the phosphine oxide (4), the phosphinic chloride (5), and the triamide (6).  

Biological aspects of quinquevalent phosphorus acid chemistry, quite separate from nucleotide chemistry, have taken on increasing importance over the last few years. Throughout this year s report, although not pretending to offer comprehensive coverage of these aspects, there is an attempt to reflect this. 

The final volume of Organophosphorus Compounds , edited by Kosolapoff and Maier, contains chapters on phosphonic acids and their derivatives1 and organic derivatives of thio- (seleno-, telluro-)phosphoric acids.16 

The stereochemistry of optically active phosphorus thio-acids has been reviewed2 and published lectures have covered such topics as phosphate and phosphonate compounds based on adamantane3 and AW-dihalogeno-amides of phosphoric acids.4 

General.—Triethyl phosphite has been used to achieve stepwise O-ethylation of phosphoric and benzylphosphonic acids.5 The disulphide linkage in bis(phosphinyl) disulphides is cleaved by ammonia in a suitable solvent to yield the phosphinyl-sulphenamides (l).6 

The reaction between phosphorus dichlorides and a-hydroxyiminocarboxylic acids 

The optically active thiones (4), readily obtainable from (—)-ephedrine, undergo P—N bond fission, with inversion of configuration at phosphorus, when treated with ethanolic HC1 this provides a highly recommendable method for the preparation of valuable amounts of optically active acyclic compounds (5), isolable as the 5-methyl esters (6).9 

This year has seen an even greater emphasis on studies related to phosphonic and phosphinic acid derivatives, relative to those on phosphoric acids. A large amount of H, and NMR spectroscopic data has accumulated, and the use of such data in the confirmation of structures, as well as that of X-ray diffraction techniques, continues to be widespread. 

One brief report concerns the isolation, and characterization by i.r. spectroscopy and X-ray analysis, of a most unusual metabolite from the microorganism Gymnodinium breve (responsible for the red tide effect), and which has been shown to possess the E,E) form of the oxime structure (1).  

As in the reports for previous years, the sections headed General cover papers which describe work on phosphonic and phosphinic acid derivatives as well as those of phosphoric acid, or which describe compounds possessing more than one type of phosphyl function within the molecule. 

General.—New phosphorus-containing crown-ether compounds (2) (see also ref. 23) and dihydro-1,3,2-diazaphosphorine derivatives (3) have been prepared by conventional means. 

The phosphinosulphonates (5), prepared from the appropriate phosphino-imidazole (4), are oxidizable to the phosphinyl compounds (6). More interestingly, they can isomerize into the phosphinylsulphinate (7) when allowed to come to ambient temperature. Other examples of (5) in which = R = OEt or OPr do not isomerize in this way. The preparation of phosphorus-sulphonic anhydrides (6) has been re-investigated and three efficient methods have been described for their synthesis these are (a) the trifluoromethanesulphonic acid-assisted reaction of a phosphinic acid with a sulphonic triazolide, (Jb) interaction of a phosphinyl-imidazole and a sulphonic acid, and (c) the use of a sulphonic anhydride in reaction (6).  

Dabkowski, J. Michalski, and Z. Skrzypczynski,/. Chem. Soc., Chem. Commun., 1982, 1260. 

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