Disclosed is a process for the preparation of zolmitriptan (I), comprising:(a) diazotization of (S)-4-(4-aminobenzyl)-1 ,3-oxazolidin-2-one, or a protected form thereof, to form a diazonium intermediate, followed by reduction of the diazonium intermediate using stannous chloride to give (S)-4-(4-hydrazinobenzyl)-1,3-oxazolidin-2-one, or a protected form thereof (b) condensation of (S)-4-(4-hydrazinobenzyl)-1,3-oxazolidin-2-one, or a protected form thereof, with 4-N,N-dimethylamino-butyraldehyde, or a protected form thereof, to form a hydrazone intermediate, or a protected form thereof and (c) cyclisation of the resultant hydrazone intermediate to yield zolmitriptan (I) wherein none of the intermediates are isolated.
