THE ELECTROCHEMICAL FLUORINATION OF NITROGEN-CONTAINING CARBOXYLIC-ACIDS - FLUORINATION OF METHYL-ESTERS OF CYCLIC AMINOGROUP SUBSTITUTED CARBOXYLIC-ACIDS

Nine methyl esters of cyclic amino-group substituted carboxylic acids related to glycine, alanine or β-alanine were subjected to electrochemical fluorination. This afforded the corresponding perfluoroacid fluorides together with cleavage products in fair yields. As cyclic amino-substituents, pyrrolidino-, morpholino-, piperidino-, hexamethyleneimino- and N′-methyl-piperazinyl-groups were investigated. The formation of cyclized by-products was not observed, which contrasts with the fluorination of aliphatic dialkylamino-substituted carboxylic acids. From such methyl 2-cyclic amino-propionates [cyclic amino-group: a pyrrolidino, a morpholino or a piperidino-group], the perfluorinated methyl esters were obtained together with the corresponding perfluoroacid fluorides in yields of 1∼2 % and 14∼29 % respectively. The formation of the former compounds is ascribed to the blocking effect of the bulky cyclic amino-groups. The physical properties of the new compounds obtained are reported together with their spectral (19F NMR, Mass and IR) data. © 1990.