Patent ID: 6943254

Claim:
A process for the manufacture of a compound of the formula I or a pharmaceutically acceptable salt thereof, wherein R is (1-4C)alkyl or carboxyl(1-4C)alkyl which comprises the steps of: (a) reaction of the diazonium salt of 3-amino-2-chloropyridine with a mixture of thionyl chloride in water, in the presence of an electron transfer catalyst selected from cupric chloride and cuprous chloride, to give 2-chloropyridine-3-sulfonyl chloride; (b) reaction of 2-chloropyridine-3-sulfonyl chloride with isobutyl N-(3-methoxy-5-methylpyrazin-2-yl) carbamate in the presence of an alkali metal hydride in an inert solvent to give 2-chloro-N-isobutoxycarbonyl-N-(3-methoxy-5-methylpyrazin-2-yl)pyridine-3-sulfonamide; (c) reaction of 2-chloro-N-isobutoxycarbonyl-N-(3-methoxy-5-methylpyrazin-2-yl)pyridine-3-sulfonamide with a boronic acid at the formula II: (or an anhydride or ester thereof) in the presence of a base and in the presence of a palladium (0), palladium (II), nickel (0) or nickel (II) catalyst in suitable solvent; followed by removal of the isobutoxy carbonyl protecting group; whereafter when a pharmaceutically acceptable salt of a compound of formula I is required, it is obtained by reaction with the appropriate acid or base affording a physiologically-acceptable ion, or by any other conventional salt formation procedure.