A new process is described for obtaining 5-cyanophthalide, which is an intermediate used for the synthesis of citalopram and its active enantiomer S(+) citalopram, both of which are known active ingredients commonly used for treating depression. The process involves starting from 5-carboxyphthalide which is converted into the corresponding acylochloride. The latter is reacted with hydroxylamine to produce the corresponding hydroxamyl phthalide, which is subsequently subjected to a dehydration reaction to produce 5-cyanophthalide.
