Intermediates for preparing herbicidal pyridazinones
Disclosed is a compound of Formula I, including N-oxides, and salts thereof, wherein R 1 , R 2 and R 3 are defined as set forth in the disclosure. Also disclosed is a process for preparing a compound of Formula I. A compound of Formula I can also be used as a synthetic intermediate to prepare pyridazinone-based herbicides.
1. A compound of Formula I and N-oxides and/or salts thereof
wherein
R 1 is C 1 -C 4 alkyl or C 3 -C 6 cycloalkyl;
R 2 is Cl or NH 2 ;
R 3 is OR 4 ; and
R 4 is C 1 -C 4 alkyl, SO 2 CF 3 or SO 2 (4-Me-Ph).
2. The compound of claim 1 that is a compound of Formula I-A
wherein
R 1 is C 1 -C 4 alkyl or C 3 -C 6 cycloalkyl; and
R 4 is C 1 -C 4 alkyl.
3. The compound of claim 2 wherein
R 1 is C 1 -C 4 alkyl; and
R 4 is methyl, ethyl, n-propyl or i-propyl.
4. The compound of claim 3 wherein
R 1 is methyl; and
R 4 is methyl.
5. The compound of claim 1 that is a compound of Formula I-B
wherein
R 1 is C 1 -C 4 alkyl or C 3 -C 6 cycloalkyl; and
R 4 is C 1 -C 4 alkyl.
6. The compound of claim 5 wherein
R 1 is C 1 -C 4 alkyl; and
R 4 is methyl, ethyl, n-propyl or i-propyl.
7. The compound of claim 6 wherein
R 1 is methyl; and
R 4 is methyl.
8. A process for preparing a compound of Formula I-A
wherein
R 1 is C 1 -C 4 alkyl or C 3 -C 6 cycloalkyl; and
R 4 is C 1 -C 4 alkyl
comprising reacting a compound of Formula II
wherein
R 1 is C 1 -C 4 alkyl or C 3 -C 6 cycloalkyl
with an alkoxylating agent.
9. The process of claim 8 wherein R 1 is methyl.
10. A process for preparing a compound of Formula I-B
wherein
R 1 is C 1 -C 4 alkyl or C 3 -C 6 cycloalkyl; and
R 4 is C 1 -C 4 alkyl
comprising reacting a compound of Formula I-A
wherein
R 1 is C 1 -C 4 alkyl or C 3 -C 6 cycloalkyl; and
R 4 is C 1 -C 4 alkyl
with an alkyl nitrite in the presence of CuCl or CuCl 2 .
11. The process of claim 10 wherein R 1 is methyl.
12. The process of claim 10 wherein R 4 is methyl.