Urea phosphonate diesters

The benzyl phosphonate triesters 100 reacted with isocyanates under similar conditions to give the corresponding cyclic urea phosphonate diesters 101 (2). 

The action of hot alkali on salts of the acids 195 (R = tert-a kyl) yields the acids 197, whereas nitrous acid at 0-5 °C yields the hydroxy acids 196. (l-Aminoalkyl)phosphonic diesters react with carbonyl chloride to give the corresponding isocyanates, which may be characterized as derived ureas or semicarbazides ... 

Method III) Oxazoles with ester-linked phosphonic acids 38 that were prepared from pyruvate esters 37, which were obtained via Fischer esterification as previously reported, were brominated using copper (II) bromide and subsequently cyclised with urea followed by TMSBr-mediated deprotection of phosphonate diester gave oxazoles 38 [77],... 

The oxygen in the free hydroxyl groups of diesters of phosphoric acid has been specifically analyzed by Dostrovsky and Halmann (1956) by condensation with tolyl carbodiimide. The substituted urea formed is separated and purified. On heating a sample (30 mg.) to 320°C. with copper bronze powder (1 mg.), carbon dioxide is evolved which contains the oxygen of the free hydroxyl groups of the phosphate. This method is fully described by Halmann (1959) and can presumably be used with monoesters of phosphoric acid and with various phosphonic and sulfonic acids. (See also Pinchas et al., 1962.)... 

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See also in sourсe #XX -- [ ]

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