Plant-protecting substituted isoxazolines, isoxazoles, isothiazolines and isothiazoles, and also processes for their preparation and their use

A compound of the formula (I) and salts thereof

• (R.sup.1)(R.sup.2)(R.sup.3)Si--A--Het--B--CO--Z (I)
• in which
• Het is a divalent heterocyclic radical from the group comprising the isothiazolines, isothiazoles or isoxazoles, and isoxazolines of the formulae (Ia) to (Id), ##STR12## in which X is an oxygen or sulfur atom,
• A and B independently of one another in each case are a single bond or C.sub.1 -C.sub.4 -alkylene which is unsubstituted or monosubstituted or polysubstituted by C.sub.1 -C.sub.4 -alkyl,
• R.sup.1, R.sup.2 and R.sup.3 independently of one another are alkyl, alkenyl, alkynyl or cycloalkyl, it being possible for the four last-mentioned radicals to be unsubstituted or mono- or polysubstituted by radicals from the group comprising alkoxy, alkylthio, mono- or dialkylamino, alkoxycarbonyl, alkylcarbonyloxy, cyano and halogen, furthermore phenylalkyl or phenyl which in each case are unsubstituted or mono- or polysubstituted in the phenyl radical by radicals from the group comprising alkyl, alkoxy, alkylthio, mono- and dialkylamino, alkoxycarbonyl, cyano and halogen,
• Z is hydroxyl or alkoxy, alkenyloxy, alkynyloxy, alkylthio, cycloalkoxy, phenoxy or benzyloxy, the 7 last-mentioned radicals being unsubstituted or mono- or polysubstituted by radicals from the group comprising alkoxy, alkylthio, mono- and dialkylamino, phenyl, substituted phenyl, cyano, halogenoalkyl, halogenoalkoxy and halogen, furthermore trialkylsilylmethoxy, a radical of the formula (Ie) or (If) ##STR13## where R is hydrogen or alkyl, Z.sup.1 radicals independently of one another are halogen, haloalkyl, haloalkoxy, alkyl, alkoxy or alkylthio and n is an integer from 0 to 5, or
• Z is furthermore amino, mono- or dialkylamino, cycloalkylamino, hydrazino, alkyl- or dialkylhydrazino, pyridino, morpholino, dimethylmorpholino, a radical of the formula (Ig), ##STR14## where R.sup.4 and R.sup.5 independently of one another are alkyl radicals or R.sup.4 and R.sup.5 together with the carbon atom linking them forte a cycloalkyl radical,
• furthermore a radical of the formula (Ih), ##STR15## where R.sup.6 and R.sup.7 independently of one another are hydrogen or a saturated or unsaturated acyclic hydrocarbon radical.