Benzisoxazole compounds useful as herbicides

A compound of formula (I):

• ##STR28## in which Ar is an optionally substituted aryl, pyridine or pyrazole ring system;
• R.sup.1 and R.sup.2 are independently selected from H, optionally substituted alkyl, alkenyl or alkynyl, halogen, NR.sup.a R.sup.b, or R.sup.1 and R.sup.2 together with the carbon to which they are attached form an optionally substituted alkenyl or cycloalkyl group;
• R.sup.3 is CO.sub.2 R.sup.4, CN, COR.sup.4, CH.sub.2 OR.sub.4, CH(OH)R.sup.4, CH(OR.sup.4) R.sup.5, CH.sub.2 OSO.sub.2 R.sup.4, CH.sub.2 OSO.sub.3 R.sup.4, CH.sub.2 ONR.sup.6 R.sup.7, CSNH.sub.2, COSR.sup.4, CSOR.sup.4,CONHSO.sub.2 R.sup.4, CONR.sup.6 R .sup.7, CONHNR.sup.6 R.sup.7, CONHN.sup.+ R.sup.6 R.sup.7 R.sup.8 Y.sup.-, CO.sub.2.sup.- M.sup.+ OR COON.dbd.CR.sup.6 R.sup.7 ;
• M.sup.+ is an agriculturally acceptable cation;
• Y.sup.- is an agriculturally acceptable anion;
• R.sup.4 and R.sup.5 are independently selected from H or an optionally substituted alkyl, aryl, alkenyl or alkynyl group;
• R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.a and R.sup.b are independently selected from H or an optionally substituted alkyl, alkenyl, aryl or alkynyl group or any two of R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.a and R.sup.b together with the atom to which they are attached form a cycloalkyl, pyrrolidine, piperidine or morpholine ring;
• R.sup.6 and R.sup.7 may also be a pyridine or pyrazole ring;
• W is O or NR.sup.10 where R.sup.10 is H or C.sub.1 -C.sub.3 alkyl;
• X is (CH.sub.2).sub.n, CH.dbd.CH, CH(OR.sup.c)CH.sub.2, or COCH.sub.2 ;
• where R.sup.c is H or an optionally substituted alkyl, aryl, alkenyl or alkynyl group;
• and
• n is 0, 1 or 2;
• wherein
• optional substituents for aryl and heterocyclic rings are up to 5 members selected from halogen, C.sub.1 -C.sub.3 alkyl, C.sub.1 -C.sub.10 haloalkyl, C.sub.1 -C.sub.10 haloalkoxy, nitro, cyano, C.sub.1 -C.sub.3 alkoxy, and S(O).sub.p R.sup.d where p is 0, 1 or 2 and R.sup.d is C.sub.1 -C.sub.10 alkyl;
• optional substituents for alkyl, alkenyl and alkynyl groups are one or more groups selected from halo;
• nitro;
• cyano;
• phenyl;
• CO.sub.2 R.sup.11, NHCOR.sup.11 or NHCH.sub.2 COR.sup.11 wherein R.sup.11 is hydrogen, C.sub.1 -C.sub.6 alkyl, or an agriculturally acceptable cation;
• C.sub.1 -C.sub.6 alkoxy;
• oxo;
• S(O).sub.p R.sup.d where p and R.sup.d are as defined above;
• amino;
• mono- and di-(C.sub.1 -C.sub.6)alkylamino;
• CONR.sup.12 R.sup.13 where R.sup.12 and R.sup.13 are independently hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl or C.sub.2 -C.sub.6 alkynyl;
• agriculturally acceptable cations are selected from sodium, potassium, calcium, and sulphonium or sulphoxonium ions having the formula S.sup.+ (O).sub.q R.sup.6 R.sup.7 R.sup.8 where q is 0 or 1 and ammonium or tertiary ammonium ions having the formula N.sup.+ R.sup.6 R.sup.7 R.sup.8 R.sup.9 ;
• and
• agriculturally acceptable anions are selected from halides, tetrafluoroborate, mesylate and tosylate ions.