Abstract: The compounds of formula (I): ##STR1## [in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or C.sub.1 -C.sub.5 alkyl;R.sup.3 represents hydrogen, an acyl group, a (C.sub.1 -C.sub.6 alkoxy)carbonyl group or an aralkyloxycarbonyl group;R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, C.sub.1 -C.sub.5 alkyl or C.sub.1 -C.sub.5 alkoxy, or R.sup.4 and R.sup.5 together represent a C.sub.1 14 C.sub.4 alkylenedioxy group;n is 1, 2 or 3;W represents the --CH.sub.2 --, >CO or >CH--OR.sup.6 group (in which R.sup.6 represents any one of the atoms or groups defined for R.sup.3 and may be the same as or different from R.sup.3); andY and Z are the same or different and each represents oxygen or imino]and pharmaceutically acceptable salts thereof have various valuable therapeutic effects on the blood system and may be prepared by a process which includes reacting a corresponding halopropionic acid derivative with thiourea.