- Metal-free phosphonation of heteroarene N-oxides with trialkyl phosphite at room temperature
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A new protocol is described for the conversion of heteroarene N-oxides to heteroarylphosphonates through in situ activation with bromotrichloromethane. The N-oxides of isoquinoline, quinoline, quinoxaline and 1,10-phenanthroline were fast transformed into the corresponding heteroarylphosphonates in up to 92% yield under mild conditions in the absence of solvent and metal catalysts. The good functional group tolerance, low cost, feasibility of scale up, and wide availability of reagents make this method a prominent complement to the Hirao coupling.
- Chen, Ming-Tao,You, Xia,Bai, Li-Gang,Luo, Qun-Li
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supporting information
p. 3165 - 3169
(2017/04/21)
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- 1,3-Dimethyl-2-(3-nitro-1,2,4-triazol-1-yl)-2-pyrrolidin-1-yl-1,3, 2-diazaphospholidinium hexafluorophosphate (MNTP): A powerful condensing reagent for phosphate and phosphonate esters
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A novel phosphonium-type condensing reagent, 1,3-dimethyl-2-(3-nitro-1,2,4- triazol-1-yl)-2-pyrrolidin-1-yl-1,3,2-diazaphospholidinium hexafluorophosphate (MNTP), was designed and synthesized. A 31P NMR study on the condensation reactions of ph
- Oka, Natsuhisa,Shimizu, Mamoru,Saigo, Kazuhiko,Wada, Takeshi
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p. 3667 - 3673
(2007/10/03)
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- THE INTERACTION OF PHOSPHITE ESTERS WITH α-IODOKETONES IN THE PRESENCE OF SILVER ION
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The reactions of trialkyl phosphites with α-iodoketones in the presence of silver perchlorate or silver tetrafluoroborate yield the corresponding trialkyl phosphates and tetra-alkyl pyrophosphates. Under certain conditions, CIDNP effects indicate the involvement of radical-pairs in the formation of unstable betaine intermediates.
- Hudson, Harry R.,Matthews, Ray W.,Shode, Oluyemisi O.,Yusuf, Ramon O.,Jaszay, Zsuzsa M.,et al.
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- ELECTROCHEMICALLY INDUCED PROCESSES OF FORMATION OF PHOSPHORIC ACID DERIVATIVES. 3. ELECTROSYNTHESIS FROM WHITE PHOSPHORUS IN ALCOHOL-WATER SOLUTIONS
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It has been established that the process of splitting of the P-P bonds of the white phosphorus molecules is initiated by cathode-generated nucleophiles (HO-, RO-), while functionalization of the P-H bond formed in phosphoric oligomers occurs under the action only of alcohol.The primary product after splitting of all the P-P bonds in phosphoric oligomers is dialkylphosphite (in alcohol-water media), or trialkylphosphite (in absolute alcohol), in the course of electrolysis being transformed into trialkylphosphate.Formation of esters of pyrophosphoric acid with reduced protogenic character of the medium was examined.It is proposed that under these conditions nucleophilic reagents of the type (>P)c-O- form and participate in splitting of the P-P bonds. Keywords: phosphoric acid derivatives, white phosphorus, electrosynthesis, alcohol-water solution.
- Budnikova, Yu. G.,Kargin, Yu. M.,Zaripov, I. M.,Romakhin, A. S.,Ignat'ev, Yu. A.,et al.
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p. 1580 - 1584
(2007/10/02)
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- Stereoselectivity in Fragmentation and Rearrangement of α-Hydroxyiminophosphinates and -phosphonates. A Synthetic Approach to Acylphosphon- and phosphor-amidates. Crystal Structures of Methyl (E)-α-Hydroxyiminobenzylphenylphosphinate and Methyl Benzoylphenylphosphonamidate
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Reaction of methyl benzoylphenylphosphinate 1 with hydroxylamine gave methyl α-hydroxyiminobenzylphenylphosphinate 2 as a mixture of E and Z isomers with the E isomer predominating.Pure (E)-2 when heated gave methyl N-benzoylphenylphosphonamidate 3 as the sole product.In contrast, (Z)-2 when heated gave, as a result of fragmentation, mainly methyl hydrogen phenylphosphonate 4 and benzonitrile, together with methyl N-phenylcarbamoylphenylphosphinate 5 as the minor product; the latter results from Beckmann rearrangement of (Z)-2.Analogous behaviour is exhibited by the two geometrical isomers of dimethyl α-hydroxyiminobenzylphenylphosphinate (E)-2 and methyl benzoylphenylphosphonamidate 3 are reported.
- Breuer, Eli,Schlossman, Ada,Safadi, Muhammad,Gibson, Dan,Chorev, Michael,Leader, Haim
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p. 3263 - 3269
(2007/10/02)
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- α-OXYIMINOPHOSPHONATES: CHEMICAL AND PHYSICAL PROPERTIES. REACTIONS, THEORETICAL CALCULATIONS, AND X-RAY CRYSTAL STRUCTURES OF (E) AND (Z)-DIMETHYL α-HYDROXYIMINOBENZYLPHOSPHONATES
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Dialkyl α-oxyiminoalkylphosphonates, obtained by treatment of dialkyl acylphosphonates with hydroxylamine or methoxylamine, are mostly mixtures of E and Z isomers.Structural assignments of the oximes were based on X-ray crystallographic analysis of representative compounds: (E)- and (Z)-dimethyl α-hydroxyiminobenzylphosphonates .The (31)P n.m.r. chemical shifts of the E isomers always appear at lower field than those of the corresponding Z isomers.Thermal fragmentation of (1a) affords benzonitrile and dimethyl hydrogen phosphate, with (Z)-(1a) reacting faster than the E isomer. α-Oxyiminophosphonates undergo EZ isomerisation catalysed either by acid or by base under certain conditions, the E isomer being the thermodinamically more stable one.An E + Z mixture of dialkyl α-oxyiminophosphonates can be mono-de-alkylated by non-basic nucleophiles (e.g.NaI) to afford monoalkyl oxyiminophosphonates of unchanged isomeric composition.The geometrical isomers of α-hydroxyiminophosphonates differ in their behaviour under basic conditions.While treatment of (E)-(1a) with NaOH in boiling methanol leads, by mono-de-alkylation, to sodium methyl α-hydroxyiminobenzylphosphonate , under the same conditions (Z)-(1a) undergoes fragmentation, by C-P bond cleavage, to benzonitrile and dimethyl hydrogen phosphate.Control experiments established that the fragmentation of (Z)-α-hydroxyiminophosphonates involves an intramolecular attack on the phosphorous atom by the ionized Z oriented oxime oxygen.Similar differences in behaviour are noted between the isomers of the monoanions of α-hydroxyiminophosphonates.MNDO/H Calculations demonstrate the feasibility of forming internal hydrogen bonds in Z isomers, and their possible contribution to conformational preferences.Single-crystal X-ray diffraction studies of (E)- and (Z)-(1a), and (E)-(2b), clearly identified the geometric isomers and correlated them with (1H) and (31)P n.m.r. resonances.
- Breuer,Eli,Karaman, Rafik,Goldblum, Amiram,Gibson, Dan,Leader, Haim,et. al.
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p. 3047 - 3058
(2007/10/02)
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- Phosphoryl to carbonyl migration of amino groups in mixed anhydrides
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Mixed anhydrides derived from carboxylic and aminophosphoric acids, (RO)(R'2N)P(O)OC(O)R'' (1), undergo unimolecular fragmentation yielding carboxyamides, R''C(O)NR'2, and metaphosphate esters, ROPO2.The mechanism of the amino group transfer was studied for substrate 1a (1, R = R' = Me; R'' = Ph); solvent as well as substituent effects indicate little (if any) charge development in the transition state.The effects of solvents and Lewis acids on the reaction rate and the activation parameters determined for 1a can be explained best in terms of stabilizing interactions with either carboxyamide or metaphosphate being formed in the course of reaction.The transfer of a functional group from one acyl center to another was investigated for other anhydride systems and the relative contributions of the fragmentation vs. disproportionation of substrates are discussed.
- Symes, Jill,Modro, Tomasz A.
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p. 1702 - 1708
(2007/10/02)
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- OXIDATIVE CONVERSION OF PHOSPHOROTHIOLATES TO PHOSPHINYLOXYSULFONATES PROBABLY VIA PHOSPHOROTHIOLATE S-OXIDES
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Phosphorothiolate S-oxides and their phosphinyloxysulfenate rearrangement products are probable intermediates in the facile conversion of phosphorothiolates to phosphinyloxysulfonates on peracid oxidation.They may also be intermediates in the biological oxidation of phosphorothiolates.
- Segall, Yoffi,Casida, John E.
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p. 139 - 142
(2007/10/02)
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