- One-pot Synthesis of Acid Anhydrides from Acids Using N,N,N',N'-Tetramethylchloroformamidinium Chloride under Mild Conditions
-
N,N,N',N'-Tetramethylchloroformamidinium chloride reacted smoothly with a variety of carboxylic and phosphoric acids in the presence of a tertiary amine to give the corresponding acid anhydrides in high yields.
- Fujisawa, Tamotsu,Tajima, Kazuhisa,Sato, Toshio
-
-
Read Online
- Reactions of Phosphodiester Anions with Phosgene
-
The mechanisms of reactions of phosgene with the N-methylpyridinium salts of diphenyl phosphate and 1,2-dimethylethenylene phosphate (or 4,5-dimethyl-2-oxido-2-oxo-1,3,2-dioxaphosphole) have been studied by 31P NMR spectrometry in dichloromethane at various temperatures and molar ratios of reactants.The products are mixtures of pyrophosphates and phosphorochloridates in proportions that vary with the structure of the phosphodiester and the experimental conditions.The reactions have also been carried out in benzene suspension.The conditions can be adjusted to give exclusively and in high yields (over 85percent) either bis(1,2-dimethylethenylene)pyrophosphate or 1,2-dimethylethenylene phosphorochloridate (or 2-chloro-4,5-dimethyl-2-oxo-1,3,2-dioxaphosphole).These cyclic enediol phosphoryl derivatives are excellent reagents for the synthesis of complex biological phosphodiesters.
- Ramirez, Fausto,Marecek, James F.
-
-
Read Online
- Activation of the Carboxy Terminus of a Peptide for Carboxy-Terminal Sequencing
-
Previously, we reported a new method of sequencing proteins from the carboxy terminus (C-terminus).The carboxyl group at the C-terminus is activated and derivatized into a thiohydantoin (TH).We reported that, by alkylating the TH formed at the C-terminus, the TH is converted into a readily displaced leaving group.Reaction with (-) under acidic conditions cleaves the alkylated thiohydantoin (ATH) and derivatizes the freshly exposed C-terminus into a new proteinyl-TH.The efficiency of the initial activation of the carboxy group at the C-terminus is critical to the initial yield of the first ATH residue.In order to directly observe the intermediates that form during activation of the C-terminus, a model tripeptide, acetyl-alanine-alanine-alanine-OH (Ac-Ala-Ala-Ala-OH) was subjected to the reagents used to form the peptidyl-TH, Ac-Ala-Ala-Ala-TH.The reaction was monitored by nuclear magnetic resonance spectroscopy.An oxazolone was observed to form immediately at the C-terminus during the reaction with diphenyl chlorophosphate (DPCP), tetraphenyl pyrophosphate (TPPP),or tetramethylchlorouronium chloride (TMU-Cl).The oxazolone was observed to react with an excess of the carboxy group-activating reagents while under basic conditions.Diketopiperazine formation at the C-terminus was also observed.These side reactions prevent or retard the reaction of (-) to form a peptidyl-TH and correlate with a reduced initial yield observed during automated C-terminal protein sequencing.The carboxylic acid-reactive reagents react with the side-chain carboxylic acid groups of aspartic and glutamic acid residues as well as the C-terminus.We found that the side-chain carboxylic acid gropus in a protein could be selectively amidated in the presence of the proteinyl-oxazolone at the C-terminus.
- Boyd, Victoria L.,Bozzini, MeriLisa,Guga, Piotr J.,DeFranco, Robert J.,Yuan, Pau-Miau,et al.
-
-
Read Online
- Copper(I) iodide catalyzed synthesis of thiophosphates by coupling of H -phosphonates with benzenethiols
-
A simple, efficient, and new method has been developed for the preparation of thiophosphates from benzenethiols. The method involves copper(I) iodide catalyzed coupling of thiols with H-phosphonates in the presence of triethylamine. The reaction proceeds effectively to afford the corresponding thiophosphates in moderate to good yields via an aerobic dehydrogenative coupling of H-phosphonates with benzenethiols. This method is easy, rapid, and good-yielding for the synthesis of thiophosphates from benzenethiols. Georg Thieme Verlag Stuttgart. New York.
- Kaboudin, Babak,Abedi, Yaghoub,Kato, Jun-Ya,Yokomatsu, Tsutomu
-
p. 2323 - 2327
(2013/09/02)
-
- Reactive intermediates in the H-phosphonate synthesis of oligonucleotides
-
The formation of H-phosphonate diesters is an important step in the synthesis of oligonucleotides. Using diphenylchlorophosphate as the activator for the coupling step is often accompanied by side reactions as a result of self 'capping' and other reactions of the reactive intermediate. In the absence of base, the activation of ethyl H-phosphonate with diphenylchlorophosphate probably occurs through the intermediate formation of bis diethyl pyro-di-H-phosphonate rather than the expected diphenyl ethyl pyro-H-phosphonate. Pyridine acts as a nucleophilic catalyst converting diphenylchlorophosphate to its pyridinium adduct. Several side and unwanted reactions are quantified so that conditions to minimise these can be identified.
- Powles, Nicholas,Atherton, John,Page, Michael I.
-
scheme or table
p. 5940 - 5947
(2012/08/28)
-
- Catalytic synthesis of triaryl phosphates from white phosphorus
-
Triaryl phosphates were synthesized from white phosphorus and phenols under aerobic conditions and in the presence of iron catalysts and iodine. Full conversion to phosphates was achieved without the use of chlorine, and the reactions do not produce acid waste. Triphenyl phosphate, tritolyl phosphate and tris(2,4-di-tert-butyl)phenyl phosphate were synthesized by this method with high selectivities. Various iron(III) diketonates were used to catalyze the conversion. Mechanistic studies showed that the reaction proceeds by formation of PI3, then O=PI(OPh)2 before the final formation of the phosphate. The nucleophilic substitution of O=PI(OPh)2 with phenol to form O=P(OPh)3 was found to be the rate-limiting step.
- Armstrong, Kenneth M.,Kilian, Petr
-
p. 2138 - 2147
(2011/06/28)
-
- New aspects connected with the synthesis of H-phosphinate anhydrides
-
A novel reaction between sodium salt of phenylphosphinic acid PhP(O)(OH)H (1) and various phosphorus electrophiles, R2P(O)C1 (2; R = alkyl, aryl, alkoxy or aryloxy) has been described. The presented reaction showed a high selectivity (yield up to 96%) in the products of the symmetric phosphorus anhydrides, R2P(O)-O-(O)PR2(4), which preferentially come from the starting phosphorus electrophiles (2). The results demonstrate that the phosphorus-phosphorus mixed anhydrides, RPH(O)-O-(O)PR2(3) are unstable under basic condition and possibly decomposed with expulsion of a phosphinylidene (Ph-P=O) fragment (6).
- Nycz
-
experimental part
p. 589 - 594
(2009/12/26)
-
- Reaction of chlorides of phosphoric, sulfonic, and carboxylic acids on solid potassium carbonate surface under PTC circumstances
-
Simple syntheses of phosphoric (4) and carboxylic (6) acid anhydrides have been elaborated by means of solid potassium carbonate in phase-transfer catalytic acylation. Behavior of various acid chlorides, phosphoric (1), sulfonic (2), and carboxylic (8), have also been studied toward potassium carbonate in the presence of lipophilic quaternary ammonium salt.
- Jaszay, Zsuzsa M.,Petnehazy, Imre,Toe, Laszlo
-
p. 447 - 450
(2007/10/03)
-
- Reinvestigation of the 31P NMR evidence for the formation of diorganyl phosphoropyridinium intermediates
-
The 31P nuclear magnetic resonance (NMR) evidence for the formation of diorganyl phosphoropyridinium intermediates was reinvestigated. It was found that equilibria of these reactions were heavily shifted to the left. The concentrations of the putative diorganyl phosphoropyridinium chlorides/bromides were usually below the detection level of this spectroscopic method. The results showed that when diphenyl iodophosphate was subjected to reaction with pyridine, the formation of a diorganyl phosphoropyridinium intermediate was observed.
- Nilsson, Johan,Kraszewski, Adam,Stawinski, Jacek
-
p. 2263 - 2266
(2007/10/03)
-
- Formation of glycol bisphosphate compounds
-
Glycol bisphosphate compounds are formed by first hydrolytically condensing a dihydrocarbylhalophosphate to form a tetrahyrocarbyl pyrophosphate and then reacting the pyrophosphate with a cyclic ether to form the glycol bisphosphate.
- -
-
-
- MODELES DE BIOTINE ACTIVEE PAR PHOSPHORYLATION TRANSFERT DE PHOSPHORYLE
-
This work describes the synthesis of the first two O-phosphobiotin models, which mimic the activated form of biotin through a phosphorylation process.In addition, pyrophosphate bond formation is considered through this kind of O-phosphorylated intermediate.Reversible interconversion of the S- and N-phosphorylated urea structures is depicted and implications of the activation process are presented.
- Etemad-Moghadam, G.,Blonski, C.,Gasc, M. B.,Perie, J. J.,Klaebe, A.
-
p. 367 - 376
(2007/10/02)
-