A compound of the formula ##STR1## wherein n, X, R.sup.3, R.sup.4 and Ar are as defined above, useful in the treatment of a condition selected from the group consisting of arthritis, cancer, tissue ulceration, restenosis, periodontal disease, epidermolysis bullosa, scleritis, bone resorption, loosening of artificial joint implants, atherosclerosis, multiple sclerosis, occular angiogenisis and other diseases characterized by matrix metalloproteinase activity, AIDS, sepsis, septic shock and other diseases involving the production of TNF.