Process for preparing acylsulfamoylbenzamides

1. A process for the preparation of a compound of formula (I):

wherein:

R 1 is hydrogen, —(CH 2 ) p -heterocyclyl or a hydrocarbon radical, where the two last-mentioned radicals are unsubstituted or substituted by one or more radicals selected from the group consisting of halogen, (C 1 -C 6 )-alkyl, (C 1 -C 6 )-haloalkyl, (C 1 -C 6 )-alkoxy, cyano and nitro;

R 2 is hydrogen, (C 1 -C 6 )-alkyl, (C 2 -C 6 )-alkenyl, (C 2 -C 6 )-alkynyl, (C 1 -C 6 )-alkoxy, (C 2 -C 6 )-alkenyloxy, where the five last-mentioned radicals are unsubstituted or substituted by one or more radicals selected from the group consisting of halogen, (C 1 -C 4 )-alkoxy and (C 1 -C 4 )-alkylthio; or R 1 and R 2 together with the linking nitrogen atom form a 3- to 8-membered saturated or unsaturated ring;

R 3 and R 5 are each independently halogen, (C 1 -C 6 )-alkyl, (C 1 -C 6 )-haloalkyl, (C 1 -C 6 )-alkoxy, S(O) q —(C 1 -C 6 )-alkyl, (C 1 -C 6 )-alkylcarbonyl, —CO-aryl, cyano or nitro; or two adjacent R 5 groups form a —O—CH 2 CH 2 — moiety;

R 4 is hydrogen, (C 1 -C 4 )-alkyl, (C 2 -C 4 )-alkenyl or (C 2 -C 4 )-alkynyl;

n is an integer from 0 to 4;

m is an integer from 0 to 5;

p is 0 or 1; and

q is 0, 1 or 2; or a salt thereof;

which process comprises the reaction of a compound of formula (II):

wherein R 3 , R 4 and n are as defined in formula (I), with a compound of formula (III):

wherein R 5 and m are as defined in formula (I) and Y is OH or Cl, in the presence of a chlorinating agent, to give a compound of formula (IV):

wherein R 3 , R 4 , R 5 , m and n are as defined in formula (I), followed by the reaction of the resultant compound of formula (IV) with a compound of formula (V):

R 1 R 2 NH  (V)

wherein R 1 and R 2 are as defined in formula (I), in the presence of a base.

2. A process as claimed in claim 1 wherein the chlorinating agent is thionyl chloride.

3. A process as claimed in claim 1 wherein the amount of chlorinating agent used is, when Y is OH from 1 to 2 molar equivalents per equivalents of (II) and (IIIa), or when Y is Cl from 1 to 2 molar equivalents per equivalent of (II).

4. A process as claimed in claim 1 wherein the solvent used in the reaction of the compound of formula (II) with the compound of formula (III) is chlorobenzene.

5. A process as claimed in claim 3 wherein the chlorinating agent is thionyl chloride.

6. A process as claimed in claim 2 wherein the solvent used in the reaction of the compound of formula (II) with the compound of formula (III) is chlorobenzene.

7. A process as claimed in claim 6 wherein the amount of chlorinating agent used is, when Y is OH from 1 to 2 molar equivalents of (II) and (IIIa) or when Y is Cl from 1 to 2 molar equivalents per equivalent of (II).

8. A process as claimed in claim 1 wherein:

R 1 is hydrogen, (C 1 -C 6 )-alkyl or (C 3 -C 6 )-cycloalkyl;

R 2 and R 4 are each hydrogen;

R 5 is (C 1 -C 6 )-alkoxy;

n is 0;

m is 0 or 1;

and the sulfamoyl group is located para to the CONR 1 R 2 moiety in the phenyl ring.

9. A process as claimed in claim 7 wherein:

R 1 is hydrogen or (C 1 -C 6 )-alkyl;

R 2 is hydrogen or (C 1 -C 6 )-alkyl;

R 4 is hydrogen;

R 5 is (C 1 -C 6 )-alkoxy;

n is 0;

m is 0 or 1;

and the sulfamoyl group is located para to the CONR 1 R 2 moiety in the phenyl ring.