Process for the preparation of herbicidal derivatives

A process for the preparation of a compound of formula I:

• wherein
• R0 is, each independently of any other, halogen, C1-C6alkyl, C2-C6alkenyl, C2-C,alkynyl, C1-C6haloalkyl, cyano-C1-C6alkyl, C2-C6haloalkenyl, cyano-C2-C6alkenyl, C2-C6haloalkynyl C2-C6alkynyl, hydroxy, hydroxy-C1-C6alkyl, C1-C6alkoxy, nitro, amino, C1-C6alkylamino, di(C1-C6alkyl)amino, C1-C6alkylcarbonylamino, C1-C6alkylsulfonylamino, C1-C6alkylaminosulfonyl, C1-C6alkylcarbonyl, C1-C6alkylcarbonyl-C1-C6alkyl, C1-C6alkoxycarbbnyl-C1-C6alkyl, C1-C6alkylcarbonyl-C2-C6alkenyl, C1-C6alkoxycarbonyl-C2-C6alkenyl, C1-C6alkylcarbonyl-C2-C6alky C1-C6alkoxycarbonyl-C2-C6alkynyl, C1-C6alkoxycarbonyl, cyano, carboxyl, phenyl or an aromatic ring that contains 1 or 2 hetero atoms selected from the group consisting of nitrogen oxygen and sulfur, wherein the latter two aromatic rings may be substituted by C1-C3alkyl, C1-C3haloalkyl, C1-C3alkoxy, C1-C3haloalkoxy, halogen, cyano or by nitro;
• R1, R2 and R3 are each independently of the others C1-C6alkyl,
• n is 0;
• R4 and R5 together with the nitrogen atoms to which they are bonded form a saturated 5- to 8-membered ring which is interrupted by oxygen;
• and
• G is hydrogen, which process comprises reacting a compound of formula II:
• wherein R0, R1, R2, R3 and n are as defined hereinbefore;
• R6 is R8R9N—;
• R7 is R10R11N— or R12O—;
• and R8, R9, R10, R11 and R12 are each independently of the others hydrogen, C1-C6alkyl, C1-C6haloalkyl, C3-C6alkenyl or benzyl, wherein the phenyl ring of the benzyl group may be substituted by C1-C4alkyl, halogen, C1-C4haloalkyl, C1-C4alkoxy or by nitro, in an inert organic solvent, optionally in the presence of a base, with a compound of formula IV, IVa or IVb:
• wherein R4 and R5 are as defined hereinbefore and H.Hal is a hydrogen halide, and optionally converting the resulting compound of formula I wherein G is a metal ion equivalent or an ammonium cation, by salt conversion into the corresponding salt of formula I wherein G is a sulfonium or phosphonium cation, or by treatment with a Brönsted acid into the corresponding compound of formula I wherein G is hydrogen.