There are described compounds exhibiting a herbicidal action of general formula: ##STR1## in which: R ##STR2## (where, R.sup.9 =alkyl, phenyl, substituted phenyl, naphthyl, cycloalkyl; R.sup.8 =alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, substituted phenyl, aralkyl, cycloalkyl;R.sup.2, R.sup.3, R.sup.4, R.sup.5 =H, alkyl, haloalkyl;R.sup.6 =--OR.sup.11, (where: R.sup.11 =H, alkaline or alkaline earth metal;R.sup.1 =phenyl, substituted phenyl, aralkyl, cycloalkyl, the --OR.sup.18 group (where R.sup.18 =alkyl, phenyl, substituted phenyl, aralkyl, substituted aralkyl), the ##STR3## group (where X=O, S and Y=phenyl, substituted phenyl, heterocycle, alkyl, haloalkyl, cycloalkyl, --R.sup.19 --X.sup.1 --R.sup.20, --X--R.sup.21, --R.sup.22 --X.sup.1 --R.sup.23 --X.sup.2 --R.sup.24, --NR.sup.25 R.sup.26, wherein: R.sup.19 =alkyl C.sub.1 -C.sub.16, aralkyl; R.sup.20 =alkyl C.sub.1 -C.sub.16, haloalkyl, alkenyl, alkynyl, cycloalkyl, phenylalkyl C.sub.7 -C.sub.13, phenyl; R.sup.21 =alkyl C.sub.1 -C.sub.16, haloalkyl, alkenyl C.sub.3 -C.sub.8, alkynyl, cycloalkyl, aralkyl, aryl, substituted aryl, --R.sup.19 --X.sup.1 --R.sup.20 ; R.sup.22,R.sup.23, R.sup.24, like or unlike are C.sub.1 -C.sub.16 alkyls;R.sup.25,R.sup.26, like or unlike are: H, alkyl C.sub.1 -C.sub.6, alkoxyl C.sub.1 -C.sub.6, phenyl, substituted phenyl; X.sup.1, X.sup.2 like or unlike are O, S, SO, SO.sub.2); n=0, 1, on condition that when n=1, R.sup.1 =phenyl, substituted phenyl, aralkyl; cycloalkyl.