4-benzoyl isoxazoles and their use as herbicides

A 4-benzoylisoxazole derivative of formula (I):

• ##STR13## wherein:
• R represents the hydrogen atom or a group --CO.sub.2 R.sup.5 ;
• R.sup.1 represents a straight- or branched-chain alkyl group having up to three carbon atoms;
• cyclopropyl or 1-methylcyclopropyl;
• R.sup.2 represents:
• a straight- or branched-chain alkyl group having up to four carbon atoms which is optionally substituted by one or more halogen atoms or one or more groups --OR.sup.51 ;
• a straight- or branched-chain alkoxy group having up to four carbon atoms which is optionally substituted by one or more halogen atoms;
• or
• a group selected from --S(O).sub.p R.sup.61, nitro and cyano;
• R.sup.3 represents a group --S(O).sub.n R.sup.6 ;
• R.sup.4 represents:
• a hydrogen, fluorine, chlorine or bromine atom;
• a straight- or branched-chain alkyl group having up to four carbon atoms which is optionally substituted by one or more halogen atoms or one or more groups --OR.sup.51 ;
• a straight- or branched-chain alkoxy group having up to four carbon atoms which is optionally substituted by one or more halogen atoms, or
• a group selected from --S(O).sub.q R.sup.61, nitro, cyano and --CO.sub.2 R.sup.52 ;
• R.sup.5 and R.sup.61, which are the same or different, each represents a straight- or branched-chain alkyl group having up to six carbon atoms which is optionally substituted by one or more halogen atoms;
• R.sup.51 represents a straight- or branched-chain alkyl group having up to four carbon atoms which is optionally substituted by one or more halogen atoms;
• R.sup.52 represents a straight- or branched-chain alkyl group having up to four carbon atoms;
• R.sup.6 represents a straight- or branched-chain alkyl, alkenyl or alkynyl group having up to six carbon atoms which is optionally substituted by one or more halogen atoms;
• n, p and q, are be the same or different, each represents zero, one or two;
• provided that when R.sup.2 represents --S(O).sub.p R.sup.61 one of the groups n and p represents zero.