The present invention is concerned with compounds of formula (I) ##STR1## wherein R, R.sup.1 and R.sup.2 are independently selected from hydrogen and C.sub.1-4 alkyl;R.sup.3 and R.sup.4 are independently selected from hydrogen, C.sub.1-6 alkyl (including cycloalkyl) and aryl (wherein the alkyl or aryl group, which latter includes benzyl, is optionally substituted by one or more atoms or groups independently selected from halogen, C.sub.1-4 alkyl and aryl), provided R.sup.3 benzyl or substituted benzyl when R.sup.4 =H;m is an integer of from 0 to 2;n is an integer of from 0 to 3;(W) is a group of formula (i), (ii), (iii), or (iv) ##STR2## wherein Y is selected from oxygen, methylene and >N--R.sup.5, where R.sup.5 is hydrogen, C.sub.1-4 alkyl, or benzyl, Z and Z' are independently selected from >C.dbd.O, >C.dbd.S and methylene, and the chiral center * in formula (i) or (ii) is in its (S) or (R) form or is a mixture thereof in any proportions;X is a group selected fromaryl (including heteroaryl)xanthenyldibenzofuranyl which group is optionally substituted;and salts and solvates thereof, the preparation of these compounds, pharmaceutical formulations containing them and their use in medicine, particularly in the treatment of migraine.