Process for the preparation of quaternized pyridazine derivatives

A process for the preparation of a compound of formula (I) or an agronomically acceptable salt or zwitterionic species thereof:

• wherein
• A is a 6-membered heteroaryl selected from the group consisting of formula A-I to A-VII below
• wherein the jagged line defines the point of attachment to the remaining part of a compound of formula (I), p is 0, 1 or 2;
• and
• R1 is hydrogen;
• R2 is hydrogen;
• Q is (CR1aR2b)m;
• m is 1;
• each R1a and R2b are hydrogen:
• Z is selected from the group consisting of —CN, —CH2OR3, —CH(OR4)(OR4a), —C(OR4)(OR4a)(OR4b), —C(O)OR10, —C(O)NR6R7 and —S(O)2OR10;
• or
• Z is selected from the group consisting of a group of formula Za, Zb, Zc, Zd, Ze and Zf below
• wherein the jagged line defines the point of attachment to the remaining part of a compound of formula (I);
• and
• R3 is hydrogen or —C(O)OR10;
• each R4, R4a and R4b are independently selected from C1-C6alkyl;
• each R5, R5a, R5b, R5c, R5d R5e, R5f, R5g and R5h are independently selected from the group consisting of hydrogen and C1-C6alkyl;
• each R6 and R7 are independently selected from the group consisting of hydrogen and C1-C6alkyl;
• each R8 is independently selected from the group consisting of halo, —NH2, methyl and methoxy;
• R10 is selected from the group consisting of hydrogen, C1-C6alkyl, phenyl and benzyl;
• and
• R10a is selected from the group consisting of hydrogen, C1-C6alkyl, phenyl and benzyl;
• said process comprising:
• reacting a compound of formula (IV);
• wherein A, Q, Z, R1 and R2 are as defined above;
• with a compound of formula (V) or
• a salt or an N-oxide thereof;
• wherein
• each R15, R16, R17 and R18 are independently selected from the group consisting of halogen, -OR15a, -NR16aR17a and —S(O)2OR10;
• and/or
• R15 and R16 together are =O or =NR16a and/or R17 and R18 together are =O or =NR16a;
• or
• R15 and R16 together with the carbon atom to which they are attached form a 3- to 6-membered heterocyclyl, which comprises 1 or 2 heteroatoms individually selected from nitrogen and oxygen;
• or
• R15 and R17 together with the carbon atom to which they are attached form a 3- to 6-membered heterocyclyl, which comprises 1 or 2 heteroatoms individually selected from nitrogen and oxygen;
• and
• each R15a is independently selected from the group consisting of hydrogen and C1-C6alkyl;
• each R16a is independently selected from the group consisting of hydrogen and C1-C6alkyl;
• each R17a is independently selected from the group consisting of hydrogen and C1-C6alkyl;
• to give a compound of formula (I).