- LiI/TBHP Mediated Oxidative Cross-Coupling of P(O)–H Compounds with Phenols and Various Nucleophiles: Direct Access to the Synthesis of Organophosphates
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An efficient and mild method for the direct phosphorylation of phenols, alcohols, and amines with P(O)–H has been reported by LiI/TBHP mediated oxidative cross-coupling reaction. Moreover, this protocol extended to β-keto esters for the synthesis of enol phosphates using H-phosphonates. Notably, this developed method applied for the synthesis of organopesticides such as paraoxon, cyanophos, and methyl parathion. The key features of this protocol are mild conditions, short reaction time, good functional group tolerance, and broad substrate scope.
- Anitha, Thippani,Ashalu, Kashamalla Chinna,Sandeep, Mummadi,Mohd, Aabid,Wencel-Delord, Joanna,Colobert, Francoise,Reddy, Kallu Rajender
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p. 7463 - 7474
(2019/12/03)
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- Triethylphosphate/phosphorus pentoxide as an efficient reagent for the phosphorylation of phenols
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A simple, efficient, and novel method has been developed for the phosphorylation of phenols. Treatment of phenols with a mixture of triethylphosphate/phosphorus pentoxide gives the corresponding phosphate derivatives in good yields. This method is easy, rapid, and offers good yields for the phosphorylation of phenols. The reaction of triethylphosphate with phosphorus pentoxide was also studied by variable-temperature 31P-NMR spectroscopy. Copyright
- Kaboudin, Babak,Mostafalu, Ramin
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experimental part
p. 776 - 780
(2012/06/30)
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- Mechanistic studies of la3+- And Zn2+-catalyzed methanolysis of aryl phosphate and phosphorothioate triesters. Development of artificial phosphotriesterase systems
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The methanolyses of a series of O,O-diethyl O-aryl phosphates (2,5) and O,O-diethyl S-aryl phosphorothioates (6) promoted by methoxide and two metal ion systems, (La3+)2(-OCH3)2 and 4:Zn2+:-OCH3 (4 = 1,5,9- triazacyclododecane) has been studied in methanol at 25°C. Bronsted plots of the log k2 values vs. sspKa for the phenol leaving groups give βlg values of -0.70. -1.43 and -1.12 for the methanolysis of the phosphates and -0.63, -0.87 and -0.74 for the methanolysis of the phosphorothioates promoted by the methoxide, La 3+ and Zn2+ systems respectively. The kinetic data for the metal-catalyzed reactions are analyzed in terms of a common mechanism where there is extensive cleavage of the P-XAr bond in the rate-limiting transition state. The relevance of these findings to the mechanism of action of the phosphotriesterase enzyme is discussed. The Royal Society of Chemistry 2005.
- Liu, Tony,Neverov, Alexei A.,Tsang, Josephine S.W.,Brown, R. Stan
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p. 1525 - 1533
(2007/10/03)
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- Transfer of the Diethoxyphosphoryl Group between Imidazole and Aryloxy Anion Nucleophiles
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Rate constans have been measured for reaction of imidazole with aryl diethyl phosphate (k1) and of aryloxy anions with N-(diethoxyphosphoryl)imidazolium ion (k-1) in aqueous solution at 25 deg C; they obey the following linear Broensted equations: log k1 = -1.02pKArOH + 1.83 (n = 6, r = 0.989); log k-1 = 0.85pKArOH - 0.48 (n = 10, r = 0.957).The value of βeq (1.87) obtained from βlg and βnuc supports a previously determined value (1.83) for the transfer of the neutral phosphoryl group from phenolate ion nucleophiles.The pKaof (diethoxyphosphoryl)imidazolium ion is 6.04.The equilibrium constant for reaction of 4-nitrophenyl diethyl phosphate with imidazole is 5.9 x 10-6; in the case of the aryl ester from phenol with pKArOH = 4.34 the equilibrium constant is calculated to be unity.The Broensted βeq data are used to calibrate effective charges derived from previously measured βlg values for attack of nucleophiles at phosphorus bearing phenolate ion leaving groups.
- Ba-Saif, Salem,Williams, Andrew
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p. 2204 - 2209
(2007/10/02)
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