Electrochemical fluorination of several methyl and/or ethyl esters of morpholino-substituted carboxylic acids

Seven methyl and/or ethyl esters of carboxylic acids (-CH2CH2C(O)OEt, -CH2CH2CH2C(O)OMe, -CH2CH2CH2C(O)OEt, -CH2CH2CH2C(O)OEt, -CH(C2H5)C(O)OMe, -CH(n-C3H7)C(O)OME, -CH2CH2CH2CH2C(O)OEt and -CH2CH2CH2CH2CH2C(O)OET) having a morpholino group were subjected to electrochemical fluorination (ECF). On ECF, the corresponding perfluoroacid fluorides bearing a perfluoromorpholino group were obtained in fair to good yields. Yields of the targeted perfluoromorpholino-containing perfluoroacid fluorides were influenced by the alpha -bond cleavage of the carboxylic acid and also by the kind of alkyl group of the carboxylic acid (the latter offering the possibility of cyclization side reactions). Perfluorooxolanes were formed as a major cyclization by-product from the ECF of morpholino-substituted carboxylic acids when the chain length of the alkyl group of the carboxylic, acids had a carbon number of three or more and the structure of the alkyl group was branched in such a way as to allow cyclization. Perfluorodioxolanes were obtained in only small yields as the specific cyclization products when the ethyl esters of carboxylic acids were subjected to ECF. Spectroscopic data, as well as physicochemical properties, are described for the new perfluoroheterocyclic compounds with a perfluoromorpholino group that were produced. (C) 2001 Elsevier Science B.V. All rights reserved.