ChemInform Abstract: NUCLEOSIDE TRANSFORMATIONS. 7. SIMPLE CONVERSION OF 2,2′-ANHYDROCYTIDINE INTO O 2′-DEOXY-2′-FLUOROCYTIDINE BY NUCLEOPHILIC SUBSTITUTION WITH POTASSIUM FLUORIDE CROWN ETHER

1978 ◽  
Vol 9 (41) ◽  
Author(s):  
R. MENGEL ◽  
W. GUSCHLBAUER
Keyword(s):  
Crown Ether ◽  
Nucleophilic Substitution ◽  
Potassium Fluoride ◽  
Simple Conversion

POTASSIUM FLUORIDE ON ALUMINA AS BASE FOR CROWN ETHER SYNTHESIS

1980 ◽  
Vol 9 (5) ◽  
pp. 533-536 ◽  
Author(s):  
Junko Yamawaki ◽  
Takashi Ando
Keyword(s):  
Crown Ether ◽  
Potassium Fluoride ◽  
Ether Synthesis

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.

A rings-in-pores net: crown ether-based covalent organic frameworks for phase-transfer catalysis

2020 ◽  
Vol 56 (4) ◽  
pp. 595-598 ◽  
Author(s):  
Ji-Chuang Shen ◽  
Wei-Ling Jiang ◽  
Wen-Di Guo ◽  
Qiao-Yan Qi ◽  
De-Li Ma ◽  
...  
Keyword(s):  
Crown Ether ◽  
Nucleophilic Substitution ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Catalytic Performance ◽  
Covalent Organic Frameworks ◽  
Substitution Reactions ◽  
Nucleophilic Substitution Reactions

The crown ether-based covalent organic frameworks show excellent phase-transfer catalytic performance in various nucleophilic substitution reactions.

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