The compounds of the formula (I) and salts thereof ##STR00001## in which R.sup.1 to R.sup.5, X.sup.1 to X.sup.4, Y.sup.1, Y.sup.2 and n and m are as defined in formula (I) according to claim 1 are suitable for use as herbicides and plant growth regulators and can be prepared by the process claimed in claim 6, via in some cases novel intermediates (see claim 11).