Compounds of formula (I): ##STR1## in which: Ar is optionally substituted phenyl; R.sup.1 is alkyl; R.sup.2 is substituted alkyl or substituted cycloalkyl; and n is 0, 1 or 2; and pharmaceutically acceptable salts and esters thereof have valuable anti-fungal properties and can be used for pharmaceutical and veterinary treatment. Methods of preparing these compounds are also provided.