Herbicidal pyridazinone compounds

1. A compound of Formula (I):

or an agronomically acceptable salt thereof,

wherein

R 1 is selected from the group consisting of hydrogen, halogen, cyano, nitro, C 1 -C 6 alkyl-, C 3 -C 6 cycloalkyl-, C 2 -C 6 -alkenyl-, C 2 -C 6 alkynyl-, C 1 -C 6 haloalkyl-, C 1 -C 6 alkoxy-, C 1 -C 3 haloalkoxy-, C 1 -C 6 alkoxy-C 1 -C 3 alkyl-, C 1 -C 6 alkyl-S(O)p- and C 1 -C 6 haloalkyl-S(O)p-;

A 1 is selected from the group consisting of O, C(O) and (CReR f );

R a , R b , R c , R d , R e and R f are each independently selected from the group consisting of hydrogen and C 1 -C 4 alkyl- wherein R a and R c may together form a C 1 -C 3 alkylene chain; and

p is 0, 1 or 2.

2. The compound according to claim 1 , wherein R 1 is C 1 -C 6 alkyl- or C 3 -C 6 cycloalkyl-.

3. The compound according to claim 1 , wherein R 1 is methyl or cyclopropyl-.

4. The compound according to claim 1 , wherein A 1 is CR e R f and R e and R f are hydrogen.

5. The compound according to claim 1 , wherein R a , R b , R c and R d are hydrogen.

6. The compound according to claim 1 , wherein R a and R c together form a —CH 2 —CH 2 — chain and R b and R d are hydrogen.

7. The compound according to claim 1 , wherein A 1 is O and R a , R b , R c and R d are methyl.

8. The compound according to claim 1 in the form of an agrochemically acceptable salt, wherein the agrochemically acceptable salt is selected from the group consisting of aluminium, calcium, cobalt, copper, iron, magnesium, potassium, sodium and zinc.

9. A herbicidal composition comprising a compound according to claim 1 and an agriculturally acceptable formulation adjuvant.

10. A herbicidal composition according to claim 9 , further comprising at least one additional pesticide.

11. A herbicidal composition according to claim 10 , wherein the additional pesticide is a herbicide or herbicide safener.

12. A method of controlling weeds at a locus comprising application to the locus of a weed controlling amount of a composition according to claim 9 .

13. A method of producing the compound of Formula (I) in claim 1 comprising:

(i) reacting, in an inert organic solvent and in the presence of a base, a compound of Formula (IIc):

where the definition of R 1 is as for Formula (I) in claim 1 and LG is a suitable leaving group, with a diketone of Formula (III)

wherein A 1 , R a , R b , R c , and R d are as for Formula (I) in claim 1 , and

(ii) rearrangement of the resulting product into the compound of Formula (I).

14. A compound of Formula (II)

wherein

R 1 is selected from the group consisting of hydrogen, halogen, cyano, nitro, C 1 -C 6 alkyl-, C 3 -C 6 cycloalkyl-, C 2 -C 6 -alkenyl-, C 2 -C 6 alkynyl-, C 1 -C 6 haloalkyl-, C 1 -C 6 alkoxy-, C 1 -C 3 haloalkoxy-, C 1 -C 6 alkoxy-C 1 -C 3 alkyl-, C 1 -C 6 alkyl-S(O)p- and C 1 -C 6 haloalkyl-S(O)p-;

p is 0, 1 or 2; and

R 2 is selected from the group consisting of halogen, OH, C 1 -C 6 alkoxy-, aryloxy and N-linked imdazolyl.

15. The compound according to claim 14 , wherein R 1 is C 3 -C 6 cycloalkyl-, C 2 -C 6 -alkenyl-, C 2 -C 6 alkynyl-, C 1 -C 6 alkoxy-C 1 -C 3 alkyl-, C 1 -C 6 alkyl-S(O)p- and C 1 -C 6 haloalkyl-S(O)p-, and wherein p is 1 or 2.

16. The compound according to claim 14 , wherein R 1 is methyl or cyclopropyl-.

17. The compound according to claim 16 , wherein R 2 is selected from the group consisting of halogen, aryloxy and N-linked imdazolyl.

18. The compound according to claim 14 , wherein R 2 is selected from the group consisting of halogen, aryloxy and N-linked imdazolyl.

19. The compound according to claim 14 , wherein R 1 is C 3 -C 6 cycloalkyl-.

20. The compound according to claim 14 , wherein R 1 is cyclopropyl.