Citalopram and other phthalanes are made by reacting a salt of a compound of formula (II) where R.sup.1 is halogen and R.sup.2 is halogen, trifluoromethyl, cyano or R--CO-- where R is a C.sub.1-4 alkyl group, with cuprous cyanide.
This application is a .sctn.371 Application of International Application No. PCT/GB02/01054, filed on Mar. 7, 2002, claiming the priority of Great Britain Application No. 0105627.4, filed Mar. 7, 2001, the entire disclosures of which are incorporated herein by reference in their entireties.
The present invention provides a process for the preparation of crude 1-[3-(dimethylamino)propyl]-1-(4-fluorophenyl)-1,3-dihydro-5-isobenzofura- n carbonitrile base with substantially low levels of impurities by arresting the formation of substantial amount of carboxamide impurity, high molecular weight impurities and suppressing the formation of desmethylcitalopram besides taking the cyanide exchange reaction to near completion and thus avoiding an extensive and expensive purification process.
