a process for preparing a novel intermediate in the preparation of perindopril is provided . also provided are improved processes for the preparation of perindopril erbumine comprising reacting a compound of formula with a silylated octahydroindole - 1h - 2 - carboxylic acid to form perindopril ; and reacting perindopril with tert - butylamine to form perindopril erbumine of formula i :