Abstract: A process for the preparation of carboxylic acids represented by a formula ##STR1## wherein R.sub.1 represents hydrogen atom or a lower alkyl radical, R.sub.2 represents hydrogen atom, lower alkyl or allyl radical and R.sub.3 represents phenyl, substituted phenyl, substituted naphthyl, dibenzofuranyl or substituted biphenyl. Following novel enamine and amidine compounds as intermediates for manufacturing the carboxylic acids and processes for the manufacture of said enamine and amidine compounds ##STR2## wherein R.sub.1, R.sub.2 and R.sub.3 represent the meanings as referred to and R.sub.4 represents dimethylamino, pyrrolidyl, piperidyl or morpholyl.