Process for the preparation of bicylic compounds and the use of this process for the preparation of an ICE inhibitor compound

A process for the preparation of the compounds of formula (I), wherein R represents a hydrogen atom, an alkyl, aryl or aralkyl radical containing up to 18 carbon atoms and the amine function can be free or protected. The process comprising cyclisation of a compound of formula (IA) in a basic medium and in the presence of; a derivative of phosphonic acid of formula P(=Z)(X1)(X2)(X3) in which Z is a sulfur or oxygen atom, X1 represents a halogen atom, X2 and X3, identical or different, represent a halogen atom, an alkyloxy radical containing 1 to 6 carbon atoms, an aryloxy radical containing 6 to 12 carbon atoms or an arylalkyloxy radical containing 7 to 15 carbon atoms, or a trimer of formula (P2).