Abstract: The invention provides an improved process for preparing rebamipide that is useful as a medicament, which makes it possible to prepare rebamipide with high purity and high yield. The invention is an improved process for preparing rebamipide of the formula (1), comprising subjecting a carbostyril amino acid compound of the formula (5) or a salt thereof containing a compound of the formula (11) as an impurity to a reduction treatment in the presence of hydrogen and a catalyst in a basic aqueous solution, thereby selectively reducing the impurity compound (11) to transform into the carbostyril amino acid compound (5); and then acylating the compound (5) in a basic aqueous solution to give rebamipide (1).

Abstract: The invention provides an improved process for preparing rebamipide that is useful as a medicament, which makes it possible to prepare rebamipide with high purity and high yield. The invention is an improved process for preparing rebamipide of the formula (1), comprising subjecting a carbostyril amino acid compound of the formula (5) or a salt thereof containing a compound of the formula (11) as an impurity to a reduction treatment in the presence of hydrogen and a catalyst in a basic aqueous solution, thereby selectively reducing the impurity compound (11) to transform into the carbostyril amino acid compound (5); and then acylating the compound (5) in a basic aqueous solution to give rebamipide (1).

Abstract: The novel indole derivatives and salts thereof represented by the general formula (1) ##STR1## possess, for example, an inhibitory effect against superoxide (O.sub.2.sup.-) released from the macrophage cells of guinea pig by stimulation and an anti-albuminuria activity against Masugi nephritis, and are useful in various clinical fields as an agent for preventing and treating diseases and cases associated with the above superoxide radical, for example, autoimmune diseases (e.g. rheumatism), arteriosclerosis, ischemic disease, ischemic encephalopathia, hepatic insufficiency and renal insufficiency, and also as an agent for preventing and treating nephritis.

Abstract: Process for preparing dihydropyridine derivatives and salts and esters thereof represented by the general formula ##STR1## from a phenyl derivative and an enamine derivative in which the phenyl derivative is prepared by reacting a compound of the formula ##STR2## with a compound of the formula ##STR3## in the presence of an aromatic amine selected from o-, m-, p- anisidine; m-, p-toluidine; p-chloroaniline; aniline and o-phenetidine.