Process for the preparation of 4-(imidazol-1-yl)benzenesulfonamide derivatives

A process for the preparation of a compound of formula II

• wherein R1 represents aryl or heteroaryl optionally substituted with one or more groups independently selected from halogen, C1-8 alkyl, C1-8 haloalkyl, R2OC0-8 alkyl, R2SC0-8 alkyl, cyano, nitro, —NR2R4, —NR2SO2R3, —SOR3, —SO2R3, —SO2NR2R4 or —CONR2R4;
• R2 represents hydrogen, C1-8 alkyl or arylC0-8 alkyl (wherein the aryl group can be optionally substituted with one or more groups selected from C1-8 alkyl, halogen, C1-8 haloalkyl, cyano, nitro, R5OC0-8 alkyl, R5SC0-8 alkyl, —NR5R6, —NR5COR3, —COR5 or —COOR5);
• R3 represents C1-8 alkyl or C1-8 haloalkyl;
• R4 represents hydrogen, C1-8 alkyl, arylC1-8 alkyl (wherein the aryl group can be optionally substituted with one or more groups selected from C1-8 alkyl, halogen, C1-8 haloalkyl, cyano, nitro, R5OC0-8 alkyl, R5SC0-8 alkyl, —NR5R6, —NR5COR3, —COR5, or —COOR5), —COR6 or —COOR6;
• R5 represents hydrogen, C1-8 alkyl or benzyl;
• R6 represents C1-8 alkyl or C1-8 haloalkyl;
• aryl represents phenyl or naphthyl;
• and
• heteroaryl represents pyridine, pyrazine, pyrimidine or pyridazine, which can be optionally fused to a benzene ring;
• and But represents tert-butyl, which comprises reacting 4-amino-N-tert-butylbenzenesulfonamide of formula III
• wherein But represents tert-butyl, with an aldehyde of formula R1—CHO (IV), wherein R1 has the meaning defined above, to produce an imine of formula V
• wherein R1 and But have the meaning defined above, then allowing to react said imine of formula V with a methylisocyanide of formula L-CH2—NC (VI), wherein L represents a leaving group, in the presence of a base, to produce an imidazole derivative of formula VII
• wherein R1 and But have the meaning defined above, and chlorinating said compound of formula VII by treatment with a chlorinating agent to produce a compound of formula II.