Phosphoric acid 4-nitrophenyl ester

The preparation of phosphate esters has been reviewed and full details have appeared of the use of 2-chloromethyl-4-nitrophenyl esters (reported last year) in the synthesis of monoesters and mixed dialkyl esters of phosphoric acid. 

Additionally, they observed a second pathway, hydrolysis through dealkylation leading to a secondary ester of phosphoric acid which still contains the p-nitrophenyl moiety, i.e., de-ethyl Parathion (O-clhyl-O-p-nilrophenyl-monothiophosphoric acid) ... 

Phosphoric acid, tri-2-tolyl ester, see Tri-o-cresyl phosphate Phosphorothioic acid, 0,0-diethyl 0-(4-nitrophenyl) ester, see Parathion... 

Freparation of pyrophosphoric acid esters. The reagent reacts with mono and di esters of phosphoric acid at room temperature to give the corresponding symmetrical di and tetra esters of pyrophosphoric acid. Yields are well-nigh quantitative. DCC reacts similarly but isolation of tetra-p-nitrophenyl pyrophosphate presented some difficulty owing to similar solubilities of the ester and the substituted urea. With di-p-tolylcarbodiimide in dioxane this difficulty was overcome. 

Enterobacteria aerogenes can be grown when dimethyl phosphate is the sole source of phosphorus, and under these conditions a phosphodiesterase can be isolated from the micro-organism which utilizes dialkyl esters of phosphoric acid as substrates. Phosphodiesterases which have been isolated hitherto utilize nucleoside 2, 3 - or 3, 5 -phosphates and 4-nitrophenyl esters as substrates. A studyhas confirmed the hypothesis that phosphate binds to uridine phosphorylase before uridine, and that uracil leaves the enzyme before ribose-1 -phosphate. 

AlO. Aldridge, W. N., and Davison, A. N., The inhibition of erythrocyte cholinesterase by tri-esters of phosphoric acid, I. Diethyl p-nitrophenyl phosphate (E600) and its analogues. Biochem. ]. 51, 62-70 (1952). 

Cleavage at the phosphorus-carbon bond in esters of (trichloromethyl)phosphonic acid under alkaline conditions has been known for many years and yields ethanol, phosphoric acid and chloroform, and a study of the kinetics has shown that as the concentration of alkali rises, CO, HCl and HCOOH are formed in increasing amounts, possibly through the sequence illustrated in Scheme 9. However, hydrolytic removal of the trichloromethyl group is possible in conditions other than alkaline. At pH 1-10, 4-nitrophenyl phenyl(trichloromethyl)phosphinate is cleaved at the P—C bond to the extent of90-100%, although this is accompanied by hydrolysis at the POC bonding with the liberation of small... 

Phosphoric acid esters Ethyl metaphosphate Phosphate buffer Quinoline phosphate Dichloro phosphites, CH OPCh Triethyl phosphate. Butyl phosphate Phenyl acid phosphate Diphenyl hydrogen phosphate Di-p-nitrophenyl hydrogen phosphate (RO)gPS... 

By acylation of amines with active derivatives of a-keto acids pyruvic acid chloride (767), p-nitrophenyl pyruvate 167, 169), carbodimide method 86. 166, 178), mixed anhydrides with phosphorous acid dichloride 436) and by activation with the cyclic esters of oxalic acid with 4,6-diphenyl-thieno-[3,4-d]-[l,3]-dioxolone-dioxide (H. Schmidt and W. Steglich, 346A). 

The addition of 18-crown-6 to a mixture of a 4-nitrophenyl phosphoric triester (or of such an ester of a phosphonic acid) with alkoxide NaOR in ROH causes a catalytic deceleration in the solvolysis, whereas for the analogous thiophosphoryl compound a... 

When 5 -0-tritylthymidine-3 -phosphate is treated with excess tri-isopropyl benzenesulphonylchloride (TPS) and thymidine, and then deprotected, the trinucleoside monophosphate (7a) is obtained. The 5-bromo- and 5-fluoro-deoxyuridine analogues (7b) and (7c) are prepared similarly. All are resistant to snake venom and spleen phosphodiesterases, and hydrolyse too slowly under physiological conditions for the cytotoxic moiety to be effective. When protected UpU is treated with bis-(4-nitrophenyl) phosphorochloridate, and subsequently with an amine or amino-acid ester, the dinucleoside phosphor-amidates (8) are formed. Although the compounds investigated split the P—N bond under the conditions required for protecting-group removal, the method has potential for the preparation of easily fissionable neutral phospho-triesters. 

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