- Asymmetric synthesis of stereogenic phosphorus P(V) centers using chiral nucleophilic catalysis
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Organophosphates have been widely used in agrochemistry, as reagents for organic synthesis, and in biochemistry. Phosphate mimics possessing four unique substituents, and thereby a chirality center, are useful in transition metal catalysis and as nucleotide therapeutics. The catalytic, stereocontrolled synthesis of phosphorus‐stereogenic centers is challenging and traditionally depends on a resolution or use of stochiometric auxiliaries. Herein, enantioenriched phosphorus centers have been synthesized using chiral nucleophilic catalysis. Racemic H‐phosphinate species were coupled with nucleophilic alcohols under halogenating conditions. Chiral phosphonate products were synthesized in acceptable yields (33–95%) and modest enantioselectivity (up to 62% ee) was observed after identification of an appropriate chiral catalyst and optimization of the solvent, base, and temperature. Nucleophilic catalysis has a tremendous potential to produce enantioenriched phosphate mimics that could be used as prodrugs or chemical biology probes.
- Brichacek, Matthew,Numan, Ahmed
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- Continuous flow esterification of a H-phosphinic acid, and transesterification of H-phosphinates and H-phosphonates under microwave conditions
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The microwave (MW)-assisted direct esterification of phenyl-H-phosphinic acid, transesterification of the alkyl phenyl-H-phosphinates so obtained, and the similar reaction of dibenzyl phosphite (DBP) were investigated in detail, and the batch accomplishme
- Henyecz, Réka,Keglevich, Gy?rgy,Kiss, Nóra Zsuzsa
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- ROBUST PHOTOCHROMIC COMPOUNDS WITH SILICON- OR PHOSPHORUS-CONTAINING HETEROCYCLIC RING AND PRODUCTION THEREOF
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In one embodiment, provided are a new class of diarylethene-containing photochromic compounds with the incorporation of silicon-or phosphorus-containing heterocycles into the "ethene" part of the diarylethene backbone that has been shown to be capable of displaying tunable, robust and thermally stable photochromic properties. Also provided are methods for synthesizing these compounds, as well as uses of these compounds as these compounds may be used as the photochromic layer in an optical recording material and other optical functioning devices.
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Page/Page column 26
(2016/01/01)
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- Addition of optically pure H-phosphinate to ketones: Selectivity, stereochemistry and mechanism
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Aromatic methyl ketones and cyclic asymmetric ketones underwent hydrophosphorylation with P-stereogenic H-P species in the presence of potassium carbonate to produce P,C-stereogenic tertiary α-hydroxyl phosphinates in excellent yields with up to 99 : 1 dr
- Sun, Yong-Ming,Xin, Nana,Xu, Zhong-Yuan,Liu, Li-Juan,Meng, Fan-Jie,Zhang, He,Fu, Bao-Ci,Liang, Qiu-Ju,Zheng, Hong-Xing,Sun, Li-Jun,Zhao, Chang-Qiu,Han, Li-Biao
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supporting information
p. 9457 - 9465
(2014/12/11)
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- T3P-assisted esterification and amidation of phosphinic acids
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A few phosphinic acids, such as phenylphosphinic acids, 1-hydroxy-3-phospholene 1-oxides and 1-hydroxyphospholane oxides are esterified with simple alcohols in the presence of propylphosphonic anhydride (T3P). If 1.1 equiv of the T3P reagent is used, the esterifications are fast and efficient at 25° C. In the case of more reactive models it was enough to apply 0.66 equiv of T3P at 85°C under microwave conditions. The amidation of 1-hydroxy-3-methyl-3-phospholene oxide could also be accomplished under similar conditions.
- Jablonkai, Erzsébet,Henyecz, Réka,Milen, Mátyás,Kóti, János,Keglevich, Gy?rgy
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p. 8280 - 8285
(2015/03/05)
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- Synthesis of 2-pyridylphosphinate and thiophosphinate derivatives by nucleophilic aromatic substitution of N-methoxypyridinium tosylates
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We developed a straightforward and cost-effective method for the synthesis of 2-pyridylphosphinate derivatives based on a nucleophilic aromatic substitution of N-methoxypyridinium salts. The method proved to be useful for synthesizing various 2-pyridylphosphinates and thiophosphinates, including an optically active compound, from H-phosphinate precursors.
- Oka, Natsuhisa,Ito, Kousuke,Tomita, Futoshi,Ando, Kaori
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supporting information
p. 1630 - 1632
(2013/02/23)
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- Novel synthesis of phosphinates by the microwave-assisted esterification of phosphinic acids
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1-Hydroxy-3-phospholene oxides (1 and 3) and phenyl-H-phosphinic acid (6) are converted to the corresponding phosphinic esters (2, 4, and 7, respectively) by reaction with simple alcohols on microwave irradiation. Under traditional heating conditions, the
- Kiss, Nora Zsuzsa,Ludanyi, Krisztina,Drahos, Laszlo,Keglevich, Gyoergy
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experimental part
p. 2392 - 2404
(2009/12/03)
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- Anomalous reaction of ethyl bromofluoro- and difluoro-acetates with dialkylphosphonites
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The Michaelis-Arbuzov reaction of ethyl α-bromo-α-fluoro- and α, α-difluoro-acetates with dialkyl phenylphosphonites leads to the formation of unusual products including a fluorophosphinate. The reaction of ethyl bromofluoracetate with diisopropyl- and dimethyl-phenylphosphonites furnishes a complex mixture of eight and five compounds respectively. Five different compounds are obtained when ethyl bromodifluoroacetate is reacted with diisopropyl phenylphosphonite. Dimethyl phenylphosphonite yields three compounds when heated with bromochloromethane. The probable mechanism of formation of the compounds and their mass spectral characterization using GC-MS, tandem MS-MS and DART techniques are presented in this paper. Copyright Taylor & Francis Group, LLC.
- Durst,Rohrbaugh,Smith,Nilles,Connell,Laramee,Munavalli
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experimental part
p. 2655 - 2668
(2009/09/25)
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- Hewitt reaction revisited
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A range of alkyl phenylphosphonites are prepared from the reaction of phenylphosphinic acid with the corresponding alkyl chloroformates. A mechanism for this reaction is proposed.
- Afarinkia, Kamyar,Yu, Hiu-Wan
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p. 781 - 783
(2007/10/03)
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- Reductive cleavage of the halogen-phosphorus, oxygen-phosphorus and phosphorus-phosphorus bonds with alkali metals
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The reduction of phosphorus acid chlorides as well as hypophosphates, pyrophosphates and mixed P(III)-P(V) anhydrides with alkali metals (Li, Na, K) in NH3 liq. / THF solution and potassium naphthalenide was investigated. It was found that this type of phosphorus compounds easily undergo reduction: a) >P(O)Cl to >P(O)H; b) >P(O)P(O)P(O)H; c) >P(O)-O-P(O)P(O)OH and >P(O)H; d) >P(O)-O-PP(O)O- and >P-. The results of our experiments strongly suggest that the mixed P(III)-P(V) anhydride is reduced by potassium naphthalenide in THF with the cleavage of the P(III)-oxygen bond.
- Nycz, Jacek,Rachon, Janusz
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- Orthosilicate-mediated esterification of monosubstituted phosphinic acids
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(matrix presented) Monosubstituted phosphinic acids are esterified with orthosilicates in excellent yields. Phosphinylidene-containing acids react selectively under these conditions, while disubstituted phosphinic acids and phosphonic acids remain unchanged. One-pot procedures are also described for the preparation of phosphinate esters from an alcohol. This novel method provides a convenient and general alternative to more commonly employed conditions such as diazomethane or carbodiimide.
- Dumond, Yves R.,Baker, Rhonda L.,Montchamp, Jean-Luc
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p. 3341 - 3344
(2007/10/03)
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- Phosphinic acid analogues of GABA. 2. Selective, orally active GABA(B) antagonists
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In 1987, 25 years after the synthesis of the potent and selective GABA(B) agonist baclofen (1), Kerr et al. described the first GABA(B) antagonist phaclofen 2. However, phaclofen and structurally similar derivatives 3-5 did not cross the blood-brain barrier and hence were inactive in vivo as central nervous system agents. As a consequence, the therapeutic potential of GABA(B) antagonists remained unclear. In exploring GABA and baclofen derivatives by replacing the carboxylic acid residue with various phosphinic acid groups, we discovered more potent and water soluble GABA(B) antagonists. Electrophysiological experiments in vivo demonstrated that some of the new compounds were capable of penetrating the blood-brain barrier after oral administration. Neurotransmitter release experiments showed that they interacted with several presynaptic GABA(B) receptor subtypes, enhancing the release of GABA, glutamate, aspartate, and somatostatin. The new GABA(B) antagonists interacted also with postsynaptic GABA(B) receptors, as they blocked late inhibitory postsynaptic potentials. They facilitated the induction of long-term potentiation in vitro and in vivo, suggesting potential cognition enhancing effects. Fifteen compounds were investigated in various memory and learning paradigms in rodents. Although several compounds were found to be active, only 10 reversed the age-related deficits of old rats in a multiple-trial one-way active avoidance test after chronic treatment. The cognition facilitating effects of 10 were confirmed in learning experiments in Rhesus monkeys. The novel GABA(B) antagonists showed also protective effects in various animal models of absence epilepsy.
- Froestl,Mickel,Von Sprecher,Diel,Hall,Maier,Strub,Melillo,Baumann,Bernasconi,Gentsch,Hauser,Jaekel,Karlsson,Klebs,Maitre,Marescaux,Pozza,Schmutz,et al.
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p. 3313 - 3331
(2007/10/02)
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- The Kinetics and Mechanism of the Reactions of Acyclic Trico-ordinate Phosphorus Compounds with Diethyl Peroxide
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The kinetics of the reactions of acyclic phosphinites, phosphonites, and phosphines with diethyl peroxide in benzene or acetonitrile as solvent are reported together with the activation parameters for phosphinites and phosphonites and Hammett ρ values for all three types of trico-ordinate phosphorus.The data reveal a bimolecular, non-polar transition state for each reaction with ρ values are virtually independent of the nature of the trico-ordinate phosphorus species.
- Lloyd, John R.,Lowther, Nicholas,Hall, C. Dennis
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p. 245 - 250
(2007/10/02)
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