R. Weiss, Frank G. Pühlhofer, F. Hampel
Nov 1, 2001
Citations
0
Influential Citations
3
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Journal
Zeitschrift für Naturforschung B
Abstract
Various fluorosubstituted benzoylchlorides 1a-c are transformed into the corresponding acylpyridinium triflates 2a-c by one equivalent of the reagent pair 4-dimethyl-aminopyridine/ trimethylsilyltriflate (DMAP/TMSOTf). Due to the combined electrostatic and mesomeric effect of the acylpyridinium function, fluorine substituents in o- and p-positions can be subsequently substituted with a pyridinio group by additional equivalents of DMAP/ TMSOTf via an SNAr mechanism. Whereas the p-substitution product can be isolated as the highly electrophilic dication salt 3b, the corresponding mono- and bis-orthosubstituted polycation salts 3a and 3c are transformed under the reaction conditions to the 7-azoniafluorenone derivatives 4a,c by a novel cyclo-acylation. Structural and electrochemical data of these compounds are presented.