Synthesis of dinucleoside phosphates containing 5'-O-bonded 1-(6-deoxy-β-D-allofuranosyl)uracil and 1-(6-deoxy-α-L-talofuranosyl)uracil

1980 ◽  
Vol 45 (9) ◽  
pp. 2550-2557 ◽  
Author(s):  
Nella Sh. Padyukova ◽  
Jiří Smrt
Keyword(s):  
Hydrogen Chloride ◽  
Protecting Groups ◽  
Stannic Chloride ◽  
Pyridinium Salts ◽  
Ethyl Orthoformate ◽  
Methanolic Ammonia

1-O-Acetyl-2,3,5-tri-O-benzoyl-6-deoxy-L-talofuranose (IV) affords by the reaction with silylated uracil in the presence of stannic chloride, followed by the action of methanolic ammonia, 1-(6-deoxy-α-L-talofuranosyl)uracil (Vb). 1-(6-Deoxy-β-D-allofuranosyl)uracil (IIb) and/or the compound Vb reacts with ethyl orthoformate in the presence of hydrogen chloride under the formation of 2',3'-O-ethoxymethylene derivatives III or VI which afford, by the reaction with pyridinium salts of 2'-O-tetrahydropyranyl-5'-O-acetyl-(N-acetyl)ribonucleoside 3'-phosphates VIIa-VIId in the presence of N,N'-dicyclohexylcarbodiimide and the removal of protecting groups, ribonucleosid-3'-phosphorylyl-(3' → 5')-1-(6-deoxy-β-D-allofuranosyl)uracils IXa-IXd and/or ribonucleosid-3'-phosphorylyl-(3' → 5')-1-(6-deoxy-α-L-talofuranosyl)uracils Xa-Xd.

Synthesis of 6-aminohexyl esters of uridine nucleotides

1979 ◽  
Vol 44 (2) ◽  
pp. 589-592 ◽  
Author(s):  
Jiří Smrt
Keyword(s):  
Protecting Groups ◽  
Pyridinium Salts ◽  
Uridine Nucleotides

6-Aminohexyl esters of uridine 3'-phosphate (V) and uridine 5'-phosphate (VI) were prepared by condensation of 6-trifluoroacetamidohexanol (IV) with pyridinium salts of the protected corresponding phosphates by means of N,N'-dicyclohexylcarbodiimide followed by removal of protecting groups.

Synthetic use of the ribosyl derivatives of 2,4- and 2,5-thiazolidinediones

1979 ◽  
Vol 44 (5) ◽  
pp. 1475-1482 ◽  
Author(s):  
Hubert Hřebabecký ◽  
Zdeněk Točík ◽  
Jiří Beránek
Keyword(s):  
Hydrazine Hydrate ◽  
Hydrogen Chloride ◽  
Sodium Methoxide ◽  
Aqueous Ammonia ◽  
Hydroxylamine Hydrochloride ◽  
Acetyl Derivative ◽  
High Yield ◽  
Derivatives Of ◽  
Methanolic Ammonia

On ribosidation of 2,4-thiazolidinedione (2,5-thiazolidinedione, respectively), the 3-β-D-ribofuranosyl derivative is formed in high yield, either the benzoyl derivative Ia (IIa) or the acetyl derivative Ib (IIb). The unsubstituted ribosyl derivative Ic is formed from the acetyl derivative Ib by methanolic hydrogen chloride. The benzoylated ribosyl-2,4-thiazolidinedione Ia affords the benzoylated ribosylurea III on reaction with aqueous ammonia, the hydroxyethylurea derivative IVa with 2-aminoethanol, the semicarbazide derivative Va with hydrazine hydrate, the ribosylhydroxyurea derivative VIa on reaction with hydroxylamine hydrochloride and triethylamine, the benzoyl derivative of ribosylbiuret VII with O-methylisourea hydrochloride and triethylamine, and (analogously) ribosylisothiobiuret VIII with S-methylisothiourea. Methanolysis of the benzoyl derivative of hydroxyethylurea IVa with sodium methoxide affords the unprotected riboside IVb. Ribosylhydroxyurea VIb is formed on debenzoylation of compound VIa with methanolic ammonia. Acetylation of compound VIb furnishes the pentaacetyl derivative VIc.

The catalyzed polymerization of gaseous formaldehyde

1951 ◽  
Vol 205 (1083) ◽  
pp. 516-529 ◽  
Keyword(s):  
Hydrogen Chloride ◽  
Boron Trifluoride ◽  
Catalyst Concentration ◽  
Stannic Chloride ◽  
Physical Factors ◽  
Chain Process ◽  
Gaseous Formaldehyde ◽  
Kinetics Of ◽  
Gaseous Form ◽  
Phase Proceeds

Gaseous form aldehyde polymerizes rapidly if small amounts of hydrogen chloride are present and if part of the surface of the containing vessel is kept at a temperature below about 90° C; boron trifluoride and stannic chloride are also powerful catalysts for the polymerization. The kinetics of the reaction promoted by hydrogen chloride have been studied in detail. The reaction has the characteristics of a branching chain process, the rate increasing rapidly with catalyst concentration although physical factors prevent the rate becoming infinite. It has also been shown that liydrogen chloride and boron trifluoride catalyze the depolymerization of polymers of form aldehyde. There is evidence that in both polymerization and depolymerization hydrogen chloride can cause the rupture of carbon-oxygen bonds in the polyoxymethylene chain; reactive molecules are produced an d they either take up or lose molecules of form aldehyde according to the prevailing conditions. It is considered that the reaction in the gas phase proceeds by a non-ionic mechanism although the polymerization of the liquid monomer at low temperatures may involve charged intermediates.

scholarly journals Synthesis, Reactivity and Stability of Aryl Halide Protecting Groups towards Di-Substituted Pyridines

2018 ◽  
Vol 16 (1) ◽  
pp. 53
Author(s):  
Ptoton Mnangat Brian ◽  
Peter Musau
Keyword(s):  
Nitrogen Atom ◽  
Pyridine Ring ◽  
Aryl Halide ◽  
Protecting Groups ◽  
Pyridinium Salts ◽  
Substituted Pyridines ◽  
Benzyl Halides

This paper reports the synthesis and reactivity of different Benzyl derivative protecting groups. The synthesis and stability of Benzyl halides, 4-methoxybenzyl halides, 3,5-dimethoxybenzyl halides, 3,4-dimethoxybenzyl halides, 3,4,5-trimethoxybenzyl halide protecting groups and their reactivity towards nitrogen atom of a di-substituted pyridine ring in formation of pyridinium salts is also reported.

The use of 2,4,6-trimethylbenzyl esters in peptide synthesis

1966 ◽  
Vol 19 (6) ◽  
pp. 1067 ◽  
Author(s):  
FHC Stewart
Keyword(s):  
Acetic Acid ◽  
Hydrogen Chloride ◽  
Peptide Synthesis ◽  
Hydrogen Bromide ◽  
Ester Group ◽  
Protecting Groups ◽  
Reaction Conditions ◽  
Model Experiments ◽  
Benzyl Esters

Model experiments with the 2,4,6-trimethylbenzyl esters of N-acylamino acids have shown that this ester group is cleaved by hydrogen bromide in acetic acid under reaction conditions which do not affect benzyl esters appreciably, but which result in removal of benzyloxycarbonyl amino-protecting groups. 2,4,6-Trimethyl- benzyl esters, however, are unaffected by methanolic hydrogen chloride under the conditions used to cleave o-nitrophenylsulphenyl and trityl protecting groups. These selective differences have been utilized for the synthesis of various benzyloxycarbonyl peptide 2,4,6-trimethylbenzyl esters up to the hexapeptide level. Some of these derivatives have been converted into the corresponding free peptides by the action of hydrogen bromide in acetic acid. The 2,4,6-trimethylbenzyl group is more readily cleaved by hydrogen bromide than p-nitrobenzyloxycarbonyl and the possible application of this situation to peptide synthesis is considered.

Abspaltung säurelabiler Aminoschutzgruppen durch Pyridiniumsalze / The Removal of Acid-labile Amino-protecting Groups by Pyridinum Salts

1973 ◽  
Vol 28 (5-6) ◽  
pp. 334-338 ◽  
Author(s):  
H. Klostermeyer ◽  
E. Schwertner
Keyword(s):  
Amino Acids ◽  
Organic Solvents ◽  
Protecting Groups ◽  
Pyridinium Salts ◽  
Cleavage Reactions ◽  
Strong Acids ◽  
Acid Labile

Pyridinium salts of strong acids are usefull reagents in organic solvents, e. g. methanol, for the selective cleavage of acid labile amino-protecting groups as the trityl, o-nitrophenylsulfenyl, and the 2-(ρ-biphenyl)-isopropyloxycarbonyl residue. The cleavage reactions are investigated with respect to time, temperature, concentration of the reagent, different solvents, different pyridinium salts with and without addition of indole, and sterically hindrance by the structure of the amino acids.

Sign in / Sign up

Export Citation Format

Share Document