Abstract: Compounds of the general formula (I) ##STR1## in which: R.sub.1 represents a hydroxyl protecting group; andR.sub.2 represents a hydrogen or halogen atom, an azido group, a C.sub.1-3 alkyl group, a group (CH.sub.2).sub.m OR.sub.3 wherein m is zero or one and R.sub.3 represents a hydrogen atom or a hydroxyl protecting group, an azidoethoxy group, a protected hydroxyethoxy group or a group XR.sub.4 in which X is an oxygen atom or the group S(O).sub.n in which n is zero, 1 or 2 and R.sub.4 represents a C.sub.1-5 alkyl, C.sub.3-7 cycloalkyl or phenyl group or when X is oxygen or sulphur then R.sub.4 may also represent the group AlkNR.sub.5 R.sub.6 in which Alk represents a C.sub.2-6 straight or branched alkylene chain and R.sub.5 and R.sub.6 independently represent a hydrogen atom or C.sub.1-4 alkyl group or R.sub.5 and R.sub.6 together with the nitrogen atom to which they are attached form a pyrrolidino or piperidino ring or the group NR.sub.5 R.sub.6 represents a protected amino group, or R.sub.