Preparation of nematocidal sulfonamides

1. A method for preparing a compound of Formula 1

comprising (A) contacting a compound of Formula 2

wherein

R 1 is C 1 -C 4 alkyl

with a compound of Formula 3

and at least one aluminum reagent of Formula 4

wherein

R 2a , R 2b and R 2c are each independently H, Cl or C 1 -C 4 alkyl

in the presence of an inert solvent to form a first reaction product,

(B) contacting the first reaction product with an C 1 -C 4 alkanol to form a second reaction product

and (C) contacting the second reaction product with water and a protic acid to give the compound of Formula 1.

2. The method of claim 1 wherein R 1 is CH 3 or CH 2 CH 3 .

3. The method of claim 1 wherein the at least one aluminum reagent of Formula 4 comprises one or more compounds selected from the group consisting of ClAl(CH 2 CH 3 ) 2 , Cl 2 Al(CH 2 CH 3 ), Al(CH 2 CH 3 ) 3 , Al(CH 3 ) 3 , Al[CH 2 CH(CH 3 ) 2 ] 3 and HAl[CH 2 CH(CH 3 ) 2 ] 2 .

4. The method of claim 3 wherein the at least one aluminum reagent of Formula 4 comprises ClAl(CH 2 CH 3 ) 2 .

5. The method of claim 1 wherein the inert solvent comprises one or more solvents selected from the group consisting of C 1 -C 6 haloalkanes, halogenated benzenes and C 7 -C 10 aromatic hydrocarbons.

6. The method of claim 5 wherein the inert solvent comprises one or more solvents selected from the group consisting of toluene, xylenes, ethylbenzene, cumene, 1,2-dichloroethane, dichloromethane, 1,1,1-trichloroethane, chlorobenzene, 1,2-dichlorobenzene and n-chlorobutane.

7. The method of claim 6 wherein the inert solvent comprises toluene.

8. The method of claim 6 wherein the inert solvent comprises one or more solvents selected from the group consisting of 1,2-dichloroethane, dichloromethane and n-chlorobutane.

9. The method of claim 1 wherein in step (A) the temperature is in the range of 20 to 150° C.

10. The method of claim 1 wherein in step (A), the compound of Formula 2 and the compound of Formula 3 are combined in the presence of an inert solvent and then the aluminum reagent of Formula 4 is added.

11. The method of claim 1 wherein in step (B) the C 1 -C 4 alkanol comprises one or more alkanols selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol and sec-butanol.

12. The method of claim 11 wherein in step (B) the C 1 -C 4 alkanol comprises iso-propanol.

13. The method of claim 1 wherein in step (B) the temperature is in the range of 20 to 80° C.

14. The method of claim 1 wherein in step (C) the protic acid comprises one or more protic acids selected from the group consisting of acetic acid, hydrochloric acid, citric acid, formic acid and sulfuric acid.

15. The method of claim 14 wherein in step (C) the protic acid comprises acetic acid.