Abstract: A process for producing pyridiondole derivatives represented by general formula (III) or their salts (wherein R.sup.1 represents hydrogen, lower alkyl or lower alkenyl; R.sup.2 represents hydrogen, lower alkyl or halogeno; and R.sup.3 represents optionally substituted imidazolyl), which comprises reacting a compound represented by general formula (I) or its salt (wherein R.sup.1 and R.sup.2 are each as defined above) with a compound represented by general formula (II) or its salt (wherein R.sup.3.sub.a represents optionally substituted imidazolyl having an imino protecting group; and X represents halogeno), followed by a reaction for eliminating the imino protecting group); and a process for producing optically active pyridoindole derivatives represented by general formula (IV) or their salts: which comprises reacting a racemic mixture of the pyridoindole derivative represent by formula (III) or its salt with (1R)-(-)-10-camphorsulfonic acid.

Abstract: The present invention relates to synthetic intermediates useful for preparing amino acid derivatives possessing renin-inhibitory activity, and to processes for preparing the amino acid derivatives using the synthetic intermediates.

Abstract: The present invention relates to a process for producing (.+-.)-(E)-4-ethyl-2-[E-hydroxyimino]-5-nitro-3-hexenamide.

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.