Abstract: The invention relates to compounds of the general formula (I) ##STR1## and physiologically acceptable salts and solvates thereof; wherein;R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a C.sub.1-3 -alkyl group with the proviso that the sum total of carbon atom in R.sup.1 and R.sup.2 is not more than 4;X represents a direct bond or a C.sub.1-7 alkylene, C.sub.2-7 alkenylene or C.sub.2-7 alkynylene group and Y represents a direct bond or a C.sub.1-6 alkylene C.sub.2-6 alkenylene or C.sub.2-6 alknylene group with the proviso that the sum total of carbon atoms in X and Y is not more than 10;W represents a group ##STR2## wherein Z represents a group R.sup.3 (CH.sub.2).sub.q where q is 0, 1 or 2 and R.sup.3 is a group R.sup.4 CONH--, R.sup.4 NHCONH--, R.sup.4 R.sup.5 NSO.sub.2 NH--, R.sup.6 SO.sub.2 NH-- or --OH;R.sup.4 and R.sup.5 each represent a hydrogen atom or a C.sub.1-3 alkyl group;R.sup.6 represents a C.sub.1-3 alkyl group;R.sup.7 represents a chlorine atom or the group --CF.sub.

Abstract: A process is described for the preparation of a compound of formula (2) ##STR1## (wherein R is a C.sub.1-6 alkyl or a C.sub.7-20 aralkyl group) and the salts thereof, which comprises reducing a compound of formula (3) ##STR2## (or a salt thereof), using a reducing system comprising borohydride ions and metal ions selected from lanthanide ions, alkaline earth metal ions or yttrium ions in solution. The reduction system may be provided by a borohydride (e.g. NaBH.sub.4) and a metal salt (e.g. CeCl.sub.3).The ester (2) may then if desired be hydrolyzed to give the parent acid.