Nucleophilic Cyclizations with Annulated Fluorinated Heterocyclic Rings

Intramolecular Nucleophilic Cyclizations with Annulated Fluorinated Heterocyclic Rings 

Intramolecular cyclizations involving the fluorine atoms of the benzene ring and the multiple bonds of perfluoroolefins as induced by heteronucleophiles, as well as by condensations involving several molecules with suitable functional groups, are key methods for the synthesis of various heterocyclic compounds. While condensation as a method of synthesis of fluorinated heterocycles is well known and well characterized, intramolecular nucleophilic cyclization is a new technique, permitting one to obtain perfluoroalkyl derivatives of heterocyclic compounds. Due to the presence of fluorine atoms in the starting benzene molecules, cyclizations occur by elimination of ort/zo-fluorine atoms (74FCR115). 

In view of their high electronegativity, fluorine atoms accumulated in the benzene ring substantially increase the electrophilicity of the carbon atoms. This creates conditions for high mobility of the fluorine atoms of polyfluorinated aromatic compounds in nucleophilic substitution reactions and hence for intramolecular nucleophilic cyclizations by the elimination of the fluorine atom ortho to the 

A similar reaction of l-pentafluorophenyl-4-trimethylsilyl-2,4-diaza-l,3-dithia-2,3-butadiene 172 afforded 5,6,7,8-tetrafluoro-l,3,2,4-benzo-dithiadiazole 173 

To construct [7j]-annelated quinolonecarboxylic acids, Nosova et al. (97ZOR1556, 96MC15, 97MC109, 98ZOR436, 98MC131, 99ZOR1447, 

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VH. Intramolecular Nucleophilic Cyclizations with Annulated Fluorinated Heterocyclic Rings 344... 

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