The present invention relates to a compound of the formula ##STR1## wherein R.sup.1 stands for hydrogen or a lower alkyl; n denotes an integer of 1 to 6; X stands for an optionally oxidized sulphur atom, oxygen atom or an optionally substituted imino; R.sup.2 stands for methyl or an organic residual group bonded through methylene, methine a quaternary carbon; R.sup.3 stands for a lower alkyl; R.sup.4 stands for hydrogen or acyl; R.sup.5 and R.sup.6 each stand for a lower alkoxy or a lower alkyl, or R.sup.5 and R.sup.6 combinedly stand for butadienylene, and salts thereof.The compound (I) of the present invention has a strong 5-lipoxygenase inhibiting action, is of high safety and is useful as, among others, an agent for ameliorating dysfunction of circulatory system, an anti-allergic agent and a pharmaceutical agent for central nervous system.