DERIVATIVES OF ISOINDOLONE AS (3 ARTICLES, 7 ARTICLES)- OR (3 ARS, 7 ARS)-FORMS OR THEIRS MIXTURES OR THEIRS HYDROCHLORIDES, WHICH ARE ANTAGONISTS OF COMPOUND P

New isoindolone derivatives of general formula (I) in which the radicals R are hydrogen atoms or, together, form a bond, the symbols R' are phenyl radicals which may be substituted with a halogen atom or a methyl radical at position 2 or 3, X is an oxygen or sulphur atom or a radical N-R3, R3 being H, alkyl, optionally substituted, or dialkylamino, R1 is phenyl, optionally substituted, cyclohexadienyl, naphthyl or heterocyclic, R2 is H, halogen, OH, alkyl, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, alkyloxy, alkylthio, acyloxy, carboxy, alkyloxycarbonyl, optionally substituted, benzyloxycarbonyl, amino or acylamino, in their (3aR,7aR) forms or in the (3aRS,7aRS) form or mixtures thereof, where appropriate their salts where they exist and their preparation. The new derivatives according to the invention are especially advantageous as substance P antagonists.