The preparation of N-(aryl)-1,2,4-triazolopyrimidine-2-sulfonamides by the coupling of substituted 1,2,4-triazolopyrimidine-2-sulfonyl halides with aryl amines of substantially reduced nucleophilic reactivity is facilitated by conducting the reaction in the presence of a pyridine base and a catalytic amount of dimethyl sulfoxide.
N-(3-, 4-, and 5-)-pyrazolyl-1,2,4-triazolo[1,5-c]pyrimidine-2-sulfonamide compounds of formula (I),
substituted on the pyrimidine ring with an alkoxy group and on the pyrazine ring, such as N-(4-bromo-1-methylpyrazol-3-yl)-7-chloro-5-methoxy-1,2,4-triazolo[1,5-c]pyrimidine-2-sulfonamide, were prepared from alkoxy substituted 1,2,4-triazolo[1,5-c] pyrimidine-2-sulfonyl halides by condensation with substituted (3-, 4-, and 5-aminopyrazoles in the presence of a pyridine base and a catalytic amount of dimethyl sulfoxide. The compounds were found to possess general and, in some cases, selective pre- and postemergence herbicidal activity.