- Nucleophilic and acid catalysis in phosphoramidite alcoholysis
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Numerous triflates, mesylates, chlorides, trifluoroacetates and tetrazolides of trialkylammonium, pyridinium and azolium ions have been studied as activators for the reaction of N,N,O,O′-tetraisopropylphosphoramidite with propan-2-ol in acetonitrile. The progress of the reactions was followed by 31P NMR spectroscopy, and the pKa values of the activators were determined by a13C NMR spectroscopic method based on competing simultaneous protonation of two bases. The salts promoted the reaction both as acids and nucleophiles, the acidity playing a more important role than the nucleophilicity. The Bronsted α value for the general acid catalysis was observed to range from 0.6 to 0.9 and the βnucl value to be 0.2 (pKa of the conjugate acid used as the measure of nucleophilicity). Mixtures of neutral azoles or pyridines and weakly acidic ammonium salts were also shown to be useful activators that allow the acidity and nucleophilicity to be tuned independently of each other.
- Nurminen,Mattinen,Loennberg
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- Mechanisms of the Photoreactions of Cp2Fe2(CO)4 with Phosphines and Chlorocarbons
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Irradiation (λ>500 nm) of Cp2Fe2(CO)4 (Cp = η5-C5H5) in the presence of PR3 (R = Ph, O-i-Pr) in cyclohexane solution at room temperature yields a single product, Cp2Fe2(CO)3(PR3).The reaction with PPh3 (366 nm) is inhibited by excess CO.A reaction intermediate was trapped by irradiating Cp2Fe2(CO)4 in the presence of P(O-i-Pr)3 at -78 deg C in ethyl chloride or THF solution.The infrared spectrum of the intermediate has ν(CO) = 1720 cm-1, and its electronic spectrum does not exhibit a ? ->?* band.The evidence suggests that the intermediate is Cp(CO)2Fe-CO-Fe(CO)(P(O-i-Pr)3)Cp, a molecule in which a single CO bridges the Fe atoms and in which there were no direct Fe-Fe bond.The mechanism of the photoreaction of PR3 with Cp2Fe2(CO)4 is proposed to involve formation of the CO-bridged intermediate Cp2Fe2(CO)4(PR3), followed by loss of CO to give the product Cp2Fe2(CO)3(PR3).The 366-nm photoreaction of Cp2Fe2(CO)4 with CCl4 or CHCl3 to give CpFe(CO)2Cl occurs mainly by a CpFe(CO)2 radical pathway, because the chlorine atom abstraction is not inhibited by 6 atm of CO.
- Tyler, David R.,Schmidt, Maryke A.,Gray, Harry B.
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- Silver-Catalyzed Regioselective Phosphorylation of para-Quinone Methides with P(III)-Nucleophiles
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A simple and efficient method for the silver-catalyzed regioselective phosphorylation of para-quinone methides (p-QMs) with P(III)-nucleophiles (P(OR)3, ArP(OR)2, Ar2P-OR) has been established via Michaelis-Arbuzov-type reaction. A broad range of P(III)-nucleophiles and para-quinone methides are well tolerated under the mild conditions, giving the expected diarylmethyl-substituted organophosphorus compounds with good to excellent yields. Moreover, a series of corresponding enantiomers can be obtained by employing dialkyl arylphosphonite (ArP(OR)2) as substrates. The control experiments and 31P NMR tracking experiments were also performed to gain insights for the plausible reaction mechanism. This protocol may have significant implications for the formation of C(sp3)-P bonds in Michaelis-Arbuzov-type reactions.
- Liu, Yu,Tang, Ke-Wen,Wong, Wai-Yeung,Xie, Jun,Xiong, Biquan,Xu, Shipan,Xu, Weifeng
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p. 14983 - 15003
(2021/11/12)
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- ACYCLIC NUCLEOSIDE PHOSPHONATE DERIVATIVES AND MEDICINE USES THEREOF
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An acyclic nucleoside phosphonate derivative and medicine use thereof are provided. In detail, an acyclic nucleoside phosphonate derivative shown in formula I is provided, which has potent antiviral activity (such as hepatitis B virus activity) and less cytotoxicity, and pharmaceutically-acceptable salts, isomers, hydrates or solvates thereof, where, R1 is selected from H or methyl; each R2 is independently selected from -R3 or -OR3; and each R3 is independently selected from C1-C8 alkyl or C3-C8 cycloalkyl. A preparation method of the compounds shown in formula I, a pharmaceutical composition containing the compounds, and a medical application thereof are also provided. The acyclic nucleoside phosphonate derivative is effective for antivirus, such as hepatitis B virus, and is good in vivo behavior attributes.
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Page/Page column 12
(2012/11/06)
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- Syntheses und NMR-Spektren phosphororganischer Antioxidantien und verwandter Verbindungen
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The syntheses of various aliphatic, aromatic, sterically hindered, and cyclic organophosphorus compounds (phosphorous acid esters, esters chlorides and ester amides, hydrogen phosphites, phosphinates and phosphates) are reported, and general procedures for preparation are given.The compounds synthesized were investigated by means of 31P-, 1H- and 13C-n.m.r. spectroscopy, and the chemical shifts measured are listed.
- Koenig, T.,Habicher, W.D.,Haehner, U.,Pionteck, J.,Rueger, C.,Schwetlick, K.
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p. 333 - 349
(2007/10/02)
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- Insecticidal compounds
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The invention provides compounds of formula: STR1 wherein R1 represents hydrogen or halogen and R2 represents C1-8 alkyl or C1-8 haloalkyl, useful as insecticides and knockdown agents. The invention also provides compositions comprising them, methods of their use in controlling insects, and processes for their preparation.
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- Organophosphorus Antioxidants. X. The Hydroperoxide Decomposing Action of Phosphites, Phosphonites and Thiophosphites
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The kinetics and mechanism of reactions of phosphites, phosphonites, thiophosphites and hydrogenphosphites with cumyl (CHP), t-butyl (TBHP) and α-tetralyl (THP) hydrogenperoxides has been studied by means of (31)P-n.m.r. spectroscopy, high performance liquid chromatography and iodometric titration.All three valent phosphorus compounds studied initially react with hydroperoxides stoichiometrically to give the corresponding P=O products and alcohol.Some species are able to decompose cumyl hydroperoxide catalytically to form phenol and aceton.Acyloin phosphites decompose CHP catalytically after a stoichiometric reaction as thiophosphites do.Tetramethylpiperidinyl phosphites ("HALS-phosphites") react with hydroperoxides only stoichiometrically but with high velocity.Phosphonites react with hydroperoxides in the same way as the corresponding phosphites.Their reactivity, however, is much higher.Hydrogenphosphites are less reactive than phosphites in the reaction with hydroperoxides.They are able to act catalytically.
- Koenig, T.,Habicher, W. D.,Schwetlick, K.
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p. 913 - 922
(2007/10/02)
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- Organophosphorus Compounds. XIX. Synthesis of 2,3-Dihydro-1H-1,2-benzazaphosphole 2-Oxides, Variously Substituted on Nitrogen and Phosphorus, by N-P Cyclization of Zwitterionic Intermediates
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2-Phenyl-2,3-dihydro-1H-1,2-benzazaphosphole 2-oxide (7a) was prepared by thermolysis of the corresponding zwitterionic amino phosphinic acid (4), or its hydrochloride salt (1).Thermolysis of methyl (2-aminobenzyl)phenylphosphinate (5a) was accompanied by intermolecu;ar O->N transmethylation to give, after cyclization, 1-methyl-2-phenyl-2,3-dihydro-1H-1,2-benzazaphosphole 2-oxide (9a); similarly, the ethyl ester (5b) gave the N-ethyl heterocycle (9b). Reaction of 2-phthalimidobenzyl bromide (13a) with diethyl methylphosphonite (14b) gave ethyl (2-phthalimidobenzyl)methylphosphinate 15a).Hydrolysis of (15a) afforded (2-aminobenzyl)-methylphosphinic acid (16), and thermolysis of this produced 2-methyl-2,3-dihydro-1H-1,2-benzazaphosphole 2-oxide (18a). 1-Methyl-2-methoxy-2,3-dihydro-1H-1,2-benzazaphosphole 2-oxide (24) was synthesized in an analogous manner. Base catalyzed N-alkylation of the benzazaphosphole derivatives (7a) and (18a) was readily achieved, and the interconversion of 2-oxides and 2-sulfides was accomplished by conventional methods.
- Collins, David J.,Drygala, Peter F.,Swan, John M.
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p. 2517 - 2536
(2007/10/02)
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