Abstract: A process for preparing a compound of formula (I): ##STR1## in which Ar represents an aryl or substituted aryl group and R.sup.3 represents an alkyl group, which comprises reducing a compound of formula (II): ##STR2## in which Ar and R.sup.3 are as defined for formula (I), and Hal represents a halogen atom.

Abstract: Novel compounds of the formula (I), a process for their preparation and their use as collagenase inhibitors are described: ##STR1## in which, R.sub.1 is hydrogen, alkyl, or optionally substituted aryl;R.sub.2 is hydrogen, or acyl such as ##STR2## where Z is optionally substituted aryl; R.sub.3 is C.sub.3-6 alkyl;R.sub.4 is hydrogen, alkyl, --CH.sub.2 --R.sub.10 where R.sub.10 is optionally substituted phenyl or heteroaryl, or a group ##STR3## where R.sub.11 is hydrogen, alkyl, or --CH.sub.2 --Ph where Ph is optionally substituted phenyl, and R.sub.12 is hydrogen or alkyl; andR.sub.5 is hydrogen, alkyl, or a group ##STR4## where R.sub.13 is hydrogen, or alkyl, and R.sub.14 is hydroxy, alkoxy, or --NR.sub.6 R.sub.7, where each of R.sub.6 and R.sub.7 is hydrogen or alkyl, or R.sub.6 and R.sub.7 together with the nitrogen atom to which they are bonded form a 5-, 6- or 7-membered ring with an optional oxygen or sulphur atom in the ring or an optional further nitrogen atom optionally substituted by alkyl.

Abstract: A process for the preparation of the compound of formula (I): ##STR1## which process comprises reacting the compound of formula (II): ##STR2## with a chlorinating agent in the presence of a phase transfer catalyst containing chloride ions.