Synthesis of 6-tetrazolyl-substituted sulfocoumarins acting as highly potent and selective inhibitors of the tumor-associated carbonic anhydrase isoforms IX and XII

KI(hCA I) >10 μM; KI(hCA II) >10 μM; KI(hCA IX) = 6.5-68.9 nM; KI(hCA XII) = 4.3-59.8 nM.