Process and intermediates for the preparation of certain nematicidal sulfonamides

1. A method of preparing a compound of Formula C:

wherein each R 1 , R 2 , and R 3 is independently H, SF 5 , N(C 1 -C 8 alkyl)(C 1 -C 8 alkyl), C(═S)N(C 1 -C 8 alkyl)(C 1 -C 8 alkyl), SO 2 N(C 1 -C 8 alkyl)(C 1 -C 8 alkyl), OSO 2 (C 1 -C 8 alkyl), OSO 2 N(C 1 -C 8 alkyl)(C 1 -C 8 alkyl), N(C 1 -C 8 alkyl)SO 2 (C 1 -C 8 alkyl), or C 1 -C 8 alkyl, C 1 -C 8 haloalkyl, C 2 -C 8 alkenyl, C 2 -C 8 alkynyl, C 3 -C 10 cycloalkyl, C 3 -C 10 halocycloalkyl, C 4 -C 10 alkylcycloalkyl, C 4 -C 10 cycloalkylalkyl, C 6 -C 14 cycloalkylcycloalkyl, C 5 -C 10 alkylcycloalkylalkyl, C 3 -C 8 cycloalkenyl, C 1 -C 8 alkoxy, C 1 -C 8 haloalkoxy, C 3 -C 8 cycloalkoxy, C 3 -C 8 halocycloalkoxy, C 4 -C 10 cycloalkylalkoxy, C 2 -C 8 alkenyloxy, C 2 -C 8 alkynyloxy, C 1 -C 8 alkylthio, C 1 -C 8 alkylsulfinyl, C 1 -C 8 alkylsulfonyl, C 3 -C 8 cycloalkylthio, C 3 -C 8 cycloalkylsulfinyl, C 3 -C 8 cycloalkylsulfonyl, C 4 -C 10 cycloalkylalkylthio, C 4 -C 10 cycloalkylalkylsulfinyl, C 4 -C 10 cycloalkylalkylsulfonyl, C 2 -C 8 alkenylthio, C 2 -C 8 alkenylsulfinyl, C 2 -C 8 alkenylsulfonyl, C 2 -C 8 alkynylthio, C 2 -C 8 alkynylsulfinyl, C 2 -C 8 alkynylsulfonyl, or phenyl; or

two of R 1 , R 2 , and R 3 on adjacent ring atoms may be taken together to form a 5- to 7-membered carbocyclic or heterocyclic ring, each ring containing ring members selected from carbon atoms and up to 3 heteroatoms independently selected from up to 2 O, up to 2 S, and up to 3 N, wherein up to 2 carbon atom ring members are independently selected from C(═O) and C(═S) and such ring is optionally substituted with up to 3 substituents independently selected from the group consisting of C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 -C 4 haloalkenyl, C 2 -C 4 alkynyl, C 2 -C 4 haloalkynyl, C 3 -C 7 cycloalkyl, C 3 -C 7 halocycloalkyl, C 4 -C 8 alkylcycloalkyl, C 4 -C 8 haloalkylcycloalkyl, C 4 -C 8 cycloalkylalkyl, C 4 -C 8 halocycloalkylalkyl, C 1 -C 8 alkoxy, C 1 -C 8 haloalkoxy, C 2 -C 8 alkoxycarbonyl, C 2 -C 6 haloalkoxycarbonyl, C 2 -C 6 alkylcarbonyl and C 2 -C 6 haloalkylcarbonyl; and

M is an inorganic cation or organic cation;

comprising:

(a) contacting a compound of Formula A

with a solvent selected from o-dichlorobenzene (ODCB), chloroalkanes, and chloroarenes, and a first acid selected from sulfonic acids, sulfuric acid (H 2 SO 4 ), and oleum to form a compound of Formula B:

and

(b) contacting the compound of Formula B with (i) a nitrite salt MNO 2 or nitrite ester and (ii) a second acid selected from at least one inorganic acid, at least one organic acid, or mixtures thereof to form a compound of Formula C:

2. The method of claim 1 , wherein each R 1 , R 2 , and R 3 is independently H, C 1 -C 6 alkyl, C 1 -C 6 haloalkyl, C 1 -C 6 alkoxy, C 1 -C 6 haloalkoxy, or phenyl.

3. The method of claim 1 , wherein R 2 is CH 3 , CH 2 CH 3 , CF 3 , OCH 3 , OCF 3 , or OCH 2 CH 3 .

4. The method of claim 1 , wherein the second acid comprises an inorganic acid selected from hydrochloric acid (HCl), hydrobromic acid (HBr), phosphoric acid (H 3 PO 4 ), sulfuric acid (H 2 SO 4 ), and boric acid (H 3 BO 3 ).

5. The method of claim 1 , wherein the second acid comprises an organic acid selected from formic acid, acetic acid, propionic acid, citric acid, malic acid, and sulfonic acids.