Thiol based collagenase inhibitors

Abstract From the Canadian patent

A compound of the formula, wherein R1 represents lower alkyl phenyl or phenyl, lower alkyl;, R2 and R4 represent lower alkyl; and R3 represents lower alkyl, benzyloxyalkyl alkoxybenzyl, or benzyloxybenzyl wherein the oxyalkyl or alkoxy moiety contain 1 to 6 carbon atoms; and a, b, and c represent chiral centers with optional R or S stereochemistry. Such a compound inhibits mammalian collagenase and is therefore useful in the treatment or management of conditions or diseases, e.g. rheumatoid arthritis, in which collagenase promoted collagen breakdown is a causative factor.