Synthesis of 5'-O-phosphonomethyl derivatives of pyrimidine 2'-deoxynucleosides

1990 ◽  
Vol 55 (10) ◽  
pp. 2521-2536 ◽  
Author(s):  
Marcela Krečmerová ◽  
Hubert Hřebabecký ◽  
Antonín Holý
Keyword(s):  
Sodium Salt ◽  
Catalytic Hydrogenation ◽  
Bond Cleavage ◽  
Diethyl Ester ◽  
Derivatives Of

Reaction of sodium salt of 3-N,3'-O-bis(benzyloxymethyl)-2'-deoxyuridine (X) and 3-N,3'-O-bis(benzyloxymethyl)-2'-deoxythymidine (XI) with diethyl p-toluenesulfonyloxymethanephosphonate in dimethylformamide afforded diesters of the respective 5'-O-phosphonomethyl derivatives XII and XVII. Diethyl esters of 5'-O-phosphonomethyl-2'-deoxynucleosides XV and XIX, obtained after hydrogenolytic removal of the benzyloxymethyl groups, were converted into free 2'-deoxy-5'-O-phosphonomethyluridine (XVI) and a mixture of anomeric 1-(2-deoxy-5-O-phosphonomethyl-β-D-erythro-pentofuranosyl)thymines (XXIIIa, XXIIIb), respectively. Analogously, 2'-deoxy-5'-O-phosphonomethylcytidine (XXXIV) was prepared from 4-N-benzoyl-2'-deoxy-3'-O-(tetrahydro-2H-pyran-2-yl) cytidine (XXX) via diethyl ester of 2'-deoxy-5'-O-phosphonomethylcytidine (XXXIII). This compound reacted with bromotrimethylsilane to give compound XXXIV without anomerization and nucleoside bond cleavage. Condensation of the protected nucleosides X and XI with dibenzyl p-toluenesulfonyloxymethanephosphonate afforded dibenzyl esters of the corresponding 5'-O-phosphonomethyl derivatives XIII and XVIII. The free 5'-O-phosphonomethyl derivatives XVI and XXIIIa were obtained from XIII and XVIII by catalytic hydrogenation.

scholarly journals The Exchange of Cyclometalated Ligands

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 210
Author(s):  
Alexander D. Ryabov
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Cyclopalladated Complexes ◽  
Derivatives Of ◽  
Cyclometalated Ligand ◽  
Incoming Ligand

Reactions of cyclometalated compounds are numerous. This account is focused on one of such reactions, the exchange of cyclometalated ligands, a reaction between a cyclometalated compound and an incoming ligand that replaces a previously cyclometalated ligand to form a new metalacycle: + H-C*~Z ⇄ + H-C~Y. Originally discovered for PdII complexes with Y/Z = N, P, S, the exchange appeared to be a mechanistically challenging, simple, and convenient routine for the synthesis of cyclopalladated complexes. Over four decades it was expanded to cyclometalated derivatives of platinum, ruthenium, manganese, rhodium, and iridium. The exchange, which is also questionably referred to as transcyclometalation, offers attractive synthetic possibilities and assists in disclosing key mechanistic pathways associated with the C–H bond activation by transition metal complexes and C–M bond cleavage. Both synthetic and mechanistic aspects of the exchange are reviewed and discussed.

Synthesis of ?-organosilyl derivatives of propylphosphonic bichloride and diethyl ester

1962 ◽  
Vol 11 (6) ◽  
pp. 937-940
Author(s):  
E. A. Chernyshev ◽  
E. F. Bugerenko ◽  
E. D. Lubuzh ◽  
A. D. Petrov
Keyword(s):  
Diethyl Ester ◽  
Derivatives Of

Selective catalytic hydrogenation of unsaturated derivatives of nitrobenzene in alcoholic media

1999 ◽  
Vol 144 (1) ◽  
pp. 199-206 ◽  
Author(s):  
E. Lamy-Pitara ◽  
B. N'Zemba ◽  
J. Barbier ◽  
F. Barbot ◽  
L. Miginiac
Keyword(s):  
Catalytic Hydrogenation ◽  
Derivatives Of

The synthesis of amide derivatives of the sodium salt of p-aminosalicylic acid by reaction with carboxyl containing copolymer chains

1975 ◽  
Vol 9 (10) ◽  
pp. 616-618 ◽  
Author(s):  
A. F. Nikolaev ◽  
V. M. Bondarenko ◽  
O. F. Ginzburg ◽  
V. G. Rupyshev
Keyword(s):  
Sodium Salt ◽  
Aminosalicylic Acid ◽  
Amide Derivatives ◽  
Derivatives Of

Spectral properties of ionic derivatives of pyrene and their aggregates with anionic surfactant and polyelectrolyte

1995 ◽  
Vol 73 (11) ◽  
pp. 1948-1954 ◽  
Author(s):  
Pavol Hrdlovič ◽  
Lubica Horinová ◽  
Štefan Chmela
Keyword(s):  
Butyric Acid ◽  
Sodium Salt ◽  
Polyacrylic Acid ◽  
Sodium Dodecylsulfate ◽  
Green Emission ◽  
Water Soluble ◽  
Diffusion Controlled ◽  
Packed Structure ◽  
Bimolecular Quenching ◽  
Derivatives Of

A multifunctional probe based on pyrene, the chloride of the 2,2,6,6-tetramethyl-4-hydroxy-piperidinium ester of 4-(1-pyrene)butyric acid, at a concentration of 5 × 10−5 mol dm−3 exhibits excimer-like green emission with the maximum at 480 nm in the presence of sodium dodecylsulfate below its critical micelle concentration. A similar effect has been observed for this probe in the presence of the sodium salt of polyacrylic acid in the same concentration range. 1-Pyrenemethylammonium chloride exhibits a broad green excimer-like emission for sodium dodecylsulfate but not for the sodium salt of polyacrylic acid. The quenching constants of the monomeric and excimer-like emissions were determined for acrylamide, 1-oxo-2,2,6,6-tetramethyl-4-hydroxypiperidine, potassium iodide, and copper(II) sulfate, representing neutral, ionic, and free-radical types of quenchers. The rate constants of quenching for N-oxyl radicals indicate that the monomeric emission from both water-soluble probes is diffusion controlled. For other types of quenchers the rate constant of bimolecular quenching is lower. The quenching of the excimer-like emission of an aggregate of the chloride of the 2,2,6,6-tetramethyl-4-hydroxypiperidinium ester of 4-(1-pyrene)butyric acid is less efficient than in the case of 1-pyrenemethylammonium chloride, which indicates a more packed structure of the former aggregate. Keywords: pyrene, ionic derivative, emission, micelle, aggregation, quenching.

The Chemical Evolution of a Nitrogenase Model, 20 Alkyl Molybdates(VI) and the Mechanism of Hydrocarbon Production by Nitrogenase [1]

1982 ◽  
Vol 37 (3) ◽  
pp. 380-385 ◽  
Author(s):  
G. N. Schrauzer ◽  
Laura A. Hughes ◽  
Norman Strampach
Keyword(s):  
Aqueous Solution ◽  
Alkaline Hydrolysis ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Model Compounds ◽  
Hydrocarbon Production ◽  
Acidic Solutions ◽  
Reducing Conditions ◽  
Hydrolysis Of ◽  
Derivatives Of

Abstract Colorless alkylmolybdates(VI) of composition R-MoO3-are generated in aqueous solutions by the alkaline hydrolysis of complexes R-Mo(Bpy)(0)2Br(Bpy = 2,2′-bipyridyl, R = CH3 and higher alkyl). At room temperature in alkaline aqueous solution, the new organometallic derivatives of oxomolybdate(VI) are remarkably resistant against Mo-C bond hydrolysis. Decomposition occurs more rapidly on heating, affording unrearranged alkanes according to the eq.: R-MoO3- + OH-→RH + Mo04=. In acidic solutions, the methylmolybdate(VI) species decomposes with the formation of a mixture of methane and ethane while higher alkylmolybdates carrying hydrogen in the β-position relative to molybdenum undergo Mo-C bond heterolysis by way of β-elimina-tion: R-CH2CH2-MoO3 → Mo+4 (aq) + H+ + R-CH = CH2. The Mo-C bond of alkylmolybdates is resistant to oxidants but is very sensitive to cleavage under reducing conditions. Reductive Mo-C bond cleavage occurs particularly rapidly in the presence of thiols and reduced ferredoxin model compounds. The latter reactions simulate the terminal steps of hydrocarbon producing reactions of nitrogenase with alternate substrates such as CN-, R-CN or R-NC, confirming previous mechanistic conclusions concerning the mechanism of nitrogenase action.

scholarly journals Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine, histidine and tryptophan

2011 ◽  
Vol 7 ◽  
pp. 518-524 ◽  
Author(s):  
Axel G Griesbeck ◽  
Jörg Neudörfl ◽  
Alan de Kiff
Keyword(s):  
Amino Acids ◽  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Bond Cleavage ◽  
Derivatives Of

The photochemistry of phthalimide derivatives of the electron-rich amino acids tyrosine, histidine and tryptophan 8–10 was studied with respect to photoinduced electron-transfer (PET) induced decarboxylation and Norrish II bond cleavage. Whereas exclusive photodecarboxylation of the tyrosine substrate 8 was observed, the histidine compound 9 resulted in a mixture of histamine and preferential Norrish cleavage. The tryptophan derivative 10 is photochemically inert and shows preferential decarboxylation only when induced by intermolecular PET.

Determination of bioavailability of some long-chain N-substituted derivatives of L-methionine and L-lysine

1980 ◽  
Vol 58 (7) ◽  
pp. 577-580 ◽  
Author(s):  
Alenka Paquet ◽  
Ghulam Sarwar
Keyword(s):  
Ethyl Ester ◽  
Sodium Salt ◽  
Tetrahymena Pyriformis ◽  
Fatty Acyl ◽  
Protein Ratio ◽  
Rat Growth ◽  
Growth Method ◽  
The Media ◽  
Derivatives Of

The bioavailability of N-acyl-L-methionine derivatives has been determined using microbiological assay with Tetrahymena pyriformis. It was found that palmitoyl- and stearoyl-L-methionine, stearoyl-L-methionine ethyl ester, and stearoyl-L-methionine sodium salt were partially utilized (14–38%) for growth of the microorganism. These compounds partially inhibited utilization of free methionine added to the media. The shorter derivatives, acetyl-, hexanoyl-, lauroyl-, and myristoyl-L-methionine completely inhibited the growth of T. pyriformis. This effect was not reversed when DL-methionine was added to the media. N6-fatty acyl L-lysine derivatives gave low availability values (3–18%) in microbiological assessment with T. pyriformis. N2-Acetyl- and N6-acetyl-lysine did not inhibit the utilization of the added parent amino acid.Nutritional evaluation of L-methionine derivatives by the rat growth method using net protein ratio (NPR) as the performance index indicated complete availability of stearoyl-L-methionine, stearoyl-L-methionine sodium salt, and partial availability of stearoyl-L-methionine ethyl ester (52%), stearoyl-L-methionylglycine (32%), and lauroyl-L-methionine (75%).

scholarly journals Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides

2017 ◽  
Vol 13 ◽  
pp. 579-588 ◽  
Author(s):  
Jan Szabo ◽  
Julian Greiner ◽  
Gerhard Maas
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Nitrogen Atom ◽  
Catalytic Hydrogenation ◽  
Acid Chlorides ◽  
Reaction Conditions ◽  
Derivatives Of ◽  
Guanidinium Salts ◽  
Triazolium Salts

Depending on the reaction conditions, N,N’,N’’-tris(benzylamino)guanidinium salts can react with carboxylic acid chlorides to form either symmetrical N,N’,N’’-tris(N-acyl-N-benzylamido)guanidines 6 or mesoionic 4-amino-1,2,4-triazolium-3-hydrazinides 7. The latter were converted into 1,2,4-triazolium salts by protonation or methylation at the hydrazinide nitrogen atom. Neutral 1,2,4-triazoles 10 were obtained by catalytic hydrogenation of an N-benzyl derivative. Crystal structure analyses of a 4-benzylamino-1,2,4-triazolium-3-hydrazinide and of two derived 1,2,4-triazolium salts are presented.

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