Compounds represented by the general formula: ##STR00001## [wherein R.sup.1 represents methoxy, ethyl, methylthio, etc., R.sup.2, R.sup.3 and R.sup.4 each represent hydrogen, a halogen, etc., R.sup.5 and R.sup.6 each represent --X.sup.5--X.sup.6--X.sup.7 (wherein X.sup.5 represents a single bond or --CO--, X.sup.6 represents a single bond, --NR.sup.3a, etc. and X.sup.7 and R.sup.3a each represent hydrogen, C.sub.1-10 alkyl, etc.), and Ar represents phenyl, pyridyl, etc.], salts thereof and hydrates of the foregoing.