Derivatives of 2,3-difluoro-2-butenedioic acid and their isomerization reactions

1981 ◽  
Vol 46 (6) ◽  
pp. 1495-1503 ◽  
Author(s):  
Jiří Svoboda ◽  
Oldřich Paleta ◽  
Václav Dědek
Keyword(s):  
Dimethyl Sulfoxide ◽  
Nucleophilic Substitution ◽  
Thermodynamic Stability ◽  
Potassium Cyanide ◽  
Equilibrium Mixture ◽  
Potassium Fluoride ◽  
Isomerization Reaction ◽  
Acid Catalyzed ◽  
Derivatives Of ◽  
Subsequent Acid

The vinylic nucleophilic substitution of methyl trifluoropropenoate (I) with potassium cyanide affords methyl 2,3-difluoro-3-cyanopropenoate (II) in the form of a mixture of cis- and trans-isomers in 95 : 5 ratio. Simultaneously the dimerization of propenoate I to dimethyl perfluoro-4-methyl-2-pentenedioate (III) also takes place to a lesser extent. On acid catalysed methanolysis of compound II dimethyl 2,3-difluoro-2-butenedioate (VI) is formed with the same content of configurational isomers. Diester VI with a relative cis : trans ratio of 35 : 65 was obtained on dehalogenation of dimethyl 2,3-dichloro-2,3-difluorobutanedioate (V), which was prepared by addition of chlorine to the cyano derivative II and subsequent acid catalyzed methanolysis. When reacting them with potassium fluoride in dimethyl sulfoxide compounds II and VIunderwent anionic cis-trans isomerization reaction. In the 0-80 °C interval the cis isomers prevail in the equilibrium mixture, and the conversion cis → trans is endothermic: in the 40-80 °C interval for IIa → IIb ΔH = 12.8 kJ mol-1, for VIa → VIb ΔH = 38.6 kJ mol-1. The influence of the cis-effect of the fluorine atoms on the thermodynamic stability of the configurational isomers of compounds II and VI is discussed.

Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

1986 ◽  
Vol 51 (12) ◽  
pp. 2786-2797
Author(s):  
František Grambal ◽  
Jan Lasovský
Keyword(s):  
Reaction Rate ◽  
Kinetic Isotope ◽  
Acid Base Equilibrium ◽  
Mineral Acids ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Ph Scale ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

Preparation of Chloro and Sulfanyl Derivatives of 1-(2-Deoxy-4-C-hydroxymethyl-α-L-threo-Pentofuranosyl)uracil

1997 ◽  
Vol 62 (7) ◽  
pp. 1114-1127 ◽  
Author(s):  
Hubert Hřebabecký ◽  
Jan Balzarini ◽  
Antonín Holý
Keyword(s):  
Nucleophilic Substitution ◽  
Hydrogen Chloride ◽  
Thionyl Chloride ◽  
Sodium Methoxide ◽  
Thioacetic Acid ◽  
Uracil Derivatives ◽  
Derivatives Of ◽  
Hiv 1

3'-Chloro and 3'-acetylsulfanyl derivatives of 1-(2-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)uracil were prepared by reaction of 2,3'-anhydro-1-{5'-O-benzoyl-4'-C-[(benzoyloxy)methyl]-2'-deoxy-α-L-erythro-pentofuranosyl}uracil (3) with hydrogen chloride and thioacetic acid, respectively. The reaction with hydrogen chloride gave a mixture of N-1 and N-3 substituted uracil derivatives 12 and 14. Reaction of 1-{3-O-benzoyl-4-C-[(benzoyloxy)methyl]-2-deoxy-α-L-threo-pentofuranosyl}uracil (7) with thionyl chloride and subsequent debenzoylation afforded 1-(4-C-chloromethyl-2-deoxy-β-D-erythro-pentofuranosyl)uracil (19). Nucleophilic substitution with lithium thioacetate, followed by deacylation, converted 1-{3-O-benzoyl-4-C-[(benzoyloxy)methyl]-2-deoxy-5-O-p-toluenesulfonyl-α-L-threo-pentofuranosyl}uracil (9) into 1-(2-deoxy-4-C-sulfanylmethyl-β-D-erythro-pentofuranosyl)uracil (21). The obtained thiols were oxidized with iodine or air to give 1,1'-[disulfandiylbis(2,3-dideoxy-4-hydroxymethyl-α-L-threo-pentofuranose-3,1-diyl]di(pyrimidine-2,4-(1H,3H)-dione) (17) and 1,1'-[disulfandiylbis(2,5-dideoxy-4-hydroxymethyl-α-L-threo-pentofuranose-5,1-diyl]di(pyrimidine-2,4(1H,3H)-dione) (22). Reaction of 1-{3-acetylsulfanyl-5-O-methanesulfonyl-4-C-[(benzoyloxy)methyl]-2,3-dideoxy-α-L-threo-pentofuranosyl)}uracil (24) with methanolic sodium methoxide afforded 1-(3,5-anhydro-2,3-dideoxy-4-C-hydroxymethyl-3-sulfanyl-α-L-threo-pentofuranosyl)uracil (25). The same reagent was used in the preparation of 1-(3,5-anhydro-2-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)uracil (26) from 1-{4-C-[(benzoyloxy)methyl]-2-deoxy-5-O-p-toluenesulfonyl-α-L-threo-pentofuranosyl}uracil (8). From the series of 4'-substituted 2'-deoxyuridine derivatives, synthesized in this study, solely the 4'-chloromethyl derivative 19 and the oxetane derivative 26 exhibited an appreciable activity against HIV-1 and HIV-2.

Lewis-Acid-Catalyzed Direct Nucleophilic Substitution Reaction of Alcohols for the Functionalization of Aromatic Amines

2019 ◽  
Vol 4 (4) ◽  
pp. 1371-1374 ◽  
Author(s):  
Onkar S. Nayal ◽  
Maheshwar S. Thakur ◽  
Rohit Rana ◽  
Rahul Upadhyay ◽  
Sushil K. Maurya
Keyword(s):  
Nucleophilic Substitution ◽  
Lewis Acid ◽  
Aromatic Amines ◽  
Substitution Reaction ◽  
Nucleophilic Substitution Reaction ◽  
Acid Catalyzed

Heterocyclic derivatives of purines. 5. Nucleophilic substitution in series of imidazo[1,2-f]purine derivatives

1984 ◽  
Vol 20 (3) ◽  
pp. 330-334
Author(s):  
S. N. Garmash ◽  
B. A. Priimenko ◽  
N. A. Klyuev ◽  
N. I. Romanenko ◽  
A. K. Sheinkman
Keyword(s):  
Nucleophilic Substitution ◽  
Purine Derivatives ◽  
Heterocyclic Derivatives ◽  
In Series ◽  
Derivatives Of

Brønsted Acid-Catalyzed Nucleophilic Substitution of Alcohols

2006 ◽  
Vol 348 (14) ◽  
pp. 1841-1845 ◽  
Author(s):  
Roberto Sanz ◽  
Alberto Martínez ◽  
Delia Miguel ◽  
Julia M. Álvarez-Gutiérrez ◽  
Félix Rodríguez
Keyword(s):  
Nucleophilic Substitution ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Acid Catalyzed

Vicarious nucleophilic amination of nitroquinolines with 4-amino-1,2,4-triazole

2008 ◽  
Vol 86 (7) ◽  
pp. 682-685 ◽  
Author(s):  
Barbara Szpakiewicz ◽  
Maria Grzegożek
Keyword(s):  
Dimethyl Sulfoxide ◽  
Nucleophilic Substitution ◽  
Nitro Group ◽  
Para Position ◽  
Basic Medium ◽  
Ortho Position ◽  
Vicarious Nucleophilic Substitution

3-, 5-, 6-, 7- and 8-Nitroquinolines react with 4-amino-1,2,4-triazole in basic medium (potassium tert-butoxide-dimethyl sulfoxide) giving amino products of the vicarious nucleophilic substitution (VNS) of hydrogen, predominantly at ortho position to the nitro group, except 8-nitroquinoline, which reacts at para position. Additionally, furazano[3,4-f]- and furazano[3,4-h]quinoline were obtained in the case of 5- and 8- nitroquinoline, respectively. 2-Nitroquinoline was aminated to 2-quinolino(1,2,4-triazol-4-yl)amine in these conditions.Key words: nitroquinolines, vicarious nucleophilic substitution (VNS), 4-amino-1,2,4-triazole.

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