A new way of synthesizing heterocyclic primary sulfonamide probes for carbonic anhydrase.

[Display omitted] An N , N -bis(p -methoxybenzyl)-protected α-acetyl-α-diazo-methane sulfonamide proved to be a useful building block for accessing new 5-methyl-1,2,3-thiadiazole-4-sulfonamide as well as methyl 3-sulfamoyl-1 H -pyrazole-5-carboxylate. The latter was further subjected to N -alkylation and N -arylation reactions. All resulting compounds showed potent inhibition of I, II and particularly of cancer-related IX and XII isoforms of human carbonic anhydrase. [ABSTRACT FROM AUTHOR]