Process for the preparation of 1,3-diaza-spiro (4.4) non-1-en-4-one derivatives and 1-cyano-1-acylamino-cyclopentane intermediates

Process for the preparation of compounds of formula (I) wherein R means hydrogen atom, or C1-6 alkyl group, or C7-12 aralkyl group or phenyl group, characterised in that: a) the compound of formula (III) is reacted with a compound of formula (IV) wherein X means halogen atom or C1-5 alkoxy group or hydroxyl group and the resulting compound of formula (II) is transformed in the presence of an oxidising agent in a reaction medium with pH above 7, into the compound of formula (I), or b) the compound of formula (III) is reacted with an anhydride of general formula (V) and the resulting compound of formula (II) transformed in the presence of an oxidising agent, in a reaction medium with pH above 7, into the compound of formula (I), or c) a compound of formula (II) is transformed in the presence of an oxidising agent, in a reaction medium with pH above 7, into the compound of formula (I), and if desired, the resulting compounds of formula (I), before or after isolation, are transformed into acid addition salts, or the compounds of formula (I) are liberated from their acid addition salts. Thus a process for the preparation of intermediates useful in synthesis of angiotensin II antagonists is disclosed.