Process for preparing sulfonamidobenzofuran derivatives
The invention relates to a process for preparing 5-sulfonamido-benzofuran derivatives of general formula: formula (I) in which R represents an alkyl or aryl group and R 1 and R 2 represent hydrogen or an alkyl or aryl group. According to the invention, the compounds of formula I are prepared by coupling a benzofuran derivative of general formula II, where X represents chlorine, bromine or iodine or a sulfonate group: formula (II) with a sulfonamide derivative of formula R—SO 2 —NH 2 , in the presence of a basic agent and of a catalyst system formed from a complex between a palladium compound and a ligand.
1. A process for preparing 5-sulfonamidobenzofuran derivatives of general formula:
in which R represents an alkyl or aryl group and R 1 and R 2 , which may be identical or different, each represent hydrogen or an alkyl or aryl group, comprising coupling a benzofuran derivative of general formula:
in which R 1 and R 2 have the same meaning as previously and X represents chlorine, bromine or iodine or a sulfonate group of general formula:
R 3 —SO 2 —O— III
in which R 3 represents a trifluoromethane or imidazolyl group, with a sulfonamide derivative of general formula:
R—SO 2 —NH 2 IV
in which R has the same meaning as previously, in the presence of a basic agent and of a catalytic system formed from a complex between a palladium compound and a ligand wherein the palladium compound is selected from the group consisting of bis(dibenzylideneacetone)palladium(0) and tris(dibenzylideneacetone)dipalladium (0), and wherein the ligand is 2-(di-tert-butylphosphino)-2′,4′,6′-triisopropyl-1,1′-biphenyl.
2. The process as claimed in claim 1 , wherein R, R 1 or R 2 represents a linear or branched C 1 -C 8 alkyl group or a substituted or unsubstituted phenyl group.
3. The process as claimed in claim 1 , wherein R, R 1 or R 2 represents a linear or branched C 1 -C 4 alkyl group.
4. The process as claimed in claim 1 , wherein R represents methyl, R 1 represents n-butyl and R 2 represents hydrogen.
5. The process as claimed in claim 1 , wherein the basic agent is an alkali metal phosphate or an alkali metal carbonate.
6. The process as claimed in claim 5 , wherein the basic agent is tripotassium phosphate, potassium carbonate or cesium carbonate.
7. The process as claimed in claim 1 , wherein the coupling is performed at a temperature of between 60° C. and 120° C.
8. The process as claimed in claim 1 , wherein the coupling is performed in a solvent chosen from an alcohol, an ether and an aromatic hydrocarbon.
9. The process as claimed in claim 8 , wherein the solvent is dioxane.
10. The process as claimed in claim 1 wherein R 2 is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, or tert-butyl.