This invention relates to novel optionally substituted heterocyclic N-oxide compounds of formula (I): ##STR1## wherein: R, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, A, X, Z and m are defined herein. In other aspects, this invention relates to herbicidal compositions containing a optionally substituted heterocyclic N-oxide compound or derivative thereof and an agriculturally acceptable carrier and to a method of controlling undesirable vegetation by applying to an area where control is desired an herbicidally effective amount of an optionally substituted heterocyclic N-oxide compound or derivative thereof.

Substituted N-pyridinyl[1,2,4]triazolo[1,5-c]-pyrimidine-2-sulfonamide compounds, such as N-(2-fluoro-4-methyl)-7-fluoro-5-methoxy[1,2,4]triazolo[1,5-c]pyrimidine-2 -sulfonamide, were prepared by condensation of a 2-chlorosulfonyl[1,2,4]triazolo[1,5-c]pyrimidine compound, such as 2-chlorosulfonyl-7-fluoro-5-methoxy[1,2,4]triazolo[1,5-c]pyrimidine, with a substituted 3-aminopyridine compound, such as 3-amino-2-fluoro-4-methylpyridine, and found to possess herbicidal utility.

The invention provides the compounds of formula (I) and pharmaceutically acceptable derivatives thereof in which: R.sup.0 is halogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy, C.sub.1-6 alkoxy substituted by one or more fluorine atoms, or O(CH.sub.2).sub.n NR.sup.4 R.sup.5 ; R.sup.1 and R.sup.2 are independently selected from H, C.sub.1-6 alkyl, C.sub.1-6 alkyl, substituted by one or more fluorine atoms, C.sub.1-6 alkoxy, C.sub.1-6 hydroxyalkyl, SC.sub.1-6 alkyl, C(O)H, C(O)C.sub.1-6 alkyl, C.sub.1-6 alkylsulphonyl, C.sub.1-6 alkoxy substituted by one or more fluorine atoms, O(CH.sub.2).sub.n CO.sub.2 C.sub.1-6 alkyl, O(CH.sub.2).sub.n SC.sub.1-6 alkyl, (CH.sub.2).sub.n NR.sup.4 R.sup.5, (CH.sub.2).sub.n SC.sub.1-6 alkyl or C(O)NR.sup.4 R.sup.5 ; with the proviso that when R.sup.0 is at the 4-position and is halogen, at least one of R.sup.1 and R.sup.2 is C.sub.1-6 alkylsulphonyl, C.sub.1-6 alkoxy substituted by one or more fluorine atoms, O(CH.sub.2).sub.n CO.sub.2 C.sub.1-6 alkyl, O(CH.sub.2).sub.n SC.sub.1-6 alkyl, (CH.sub.2).sub.n NR.sup.4 R.sup.5 or (CH.sub.2).sub.n SC.sub.1-6 alkyl, C(O)NR.sup.4 R.sup.5 ; R.sup.3 is C.sub.1-6 alkyl or NH.sup.2 ; R.sup.4 and R.sup.5 are independently selected from H, or C.sub.1-6 alkyl or, together with the nitrogen atom to which they are attached, form a 4-8 membered saturated ring; and n is 1-4. Compounds of formula (I) are potent and selective inhibitors of COX-2 and are of use in the treatment of the pain, fever, inflammation of a variety of conditions and diseases. ##STR1##

The invention provides the compounds of formula (I) ##STR1## wherein: R.sup.0 and R.sup.1 are independently selected from H, halogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy, or C.sub.1-6 alkoxy substituted by one or more fluorine atoms; R.sup.2 is halogen, CN, CONR.sup.4 R.sup.5, CO.sub.2 H, CO.sub.2 C.sub.1-6 alkyl, or NHSO.sub.2 R.sup.4 ; R.sup.3 is C.sub.1-6 alkyl or NH.sub.2 ; and R.sup.4 and R.sup.5 are independently selected from H, C.sub.1-6 alkyl, phenyl, phenyl substituted by one or more atoms or groups (selected from halogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy, or C.sub.1-6 alkoxy substituted by one or more fluorine atoms), or together with the nitrogen atom to which they are attached form a saturated 4 to 8 membered ring; and pharmaceutically acceptable derivatives thereof. Compounds of formula (I) are potent and selective inhibitors of COX-2 and are of use in the treatment of the pain, fever, inflammation of a variety of conditions and diseases.

The invention provides a process for preparing a compound of formula (I) ##STR1## and pharmaceutically acceptable derivatives thereof wherein: R.sup.0 and R.sup.1 are independently selected from H, halogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy, or C.sub.1-6 alkoxy substituted by one or more fluorine atoms; R.sup.2 is H, C.sub.1-6 alkyl, C.sub.1-6 alkyl substituted by one or more fluorine atoms, C.sub.1-6 alkoxy, C.sub.1-6 hydroxyalkyl, SC.sub.1-6 alkyl, C(O)H, C(O)C.sub.1-6 alkyl, C.sub.1-6 alkylsulfonyl, C.sub.1-6 alkoxy substituted by one or more fluorine atoms, halogen, CN, CONR.sup.4 R.sup.5, CO.sub.2 H, CO.sub.2 C.sub.1-6 alkyl, or NHSO.sub.2 R.sup.4 ; R.sup.3 is H or phenyl substituted by SO.sub.2 C.sub.1-6 alkyl or SO.sub.2 NH.sub.2 ; R.sup.4 and R.sup.5 are independently selected from H, C.sub.1-6 alkyl, phenyl, phenyl substituted by one or more atoms or groups R.sup.6, or together with the nitrogen atom to which they are attached form a saturated 4 to 8 membered ring R.sup.6 is halogen, C.sub.1-6 alkyl, C.sub.1-6 alkoxy or C.sub.1-6 alkoxy substituted by one or more fluorine atoms; which comprises rearrangement of an azirine of formula (II) ##STR2## wherein R.sup.0 to R.sup.3 are as defined for formula (I), or a protected derivative thereof, in the presence of a catalyst and a solvent.