| 摘要 |
<p>A process for the manufacture of: wherein R is (1-4C)alkyl, carboxyl(1-4C)alkyl or 1,3,4-oxadiazol-2-yl comprises: (a) reaction of the diazonium salt of 3-amino-2-chloropyridine with thionyl chloride in water and an electron transfer catalyst; (b) reaction with isobutyl-(3-methoxy-5-methylpyrazin-2-yl)carbamate and an alkali metal hydride in inert solvent; and (I) where R is (1-4C)alkyl, carboxy(1-4C)alkyl: (c) reaction with a boronic acid: (or an anhydride or ester therof) in the presence of a base and a palladium or nickel catalyst in solvent; and removal of the isobutoxy carbonyl group; or (ii) where R is 1,3,4-oxadiazol-2-yl (c) reaction with 4-methoxycarbonylphenylboronic acid (or an anhydride or ester thereof) with a source fluoride ion under aqueous conditions; (d) removal of the isobutoxycarbonyl protecting group; (e) conversion of the methyl ester group to the hydrazide; and (f) conversion to a 1,3,4-oxadiazol-2-yl moiety.</p> |
