Among the synthesized sulfamates, C(28)-mono-substituted derivative 90 (IC50 = 4.87–9.94 μM) was the most cytotoxic compound against five tumor cell lines (518A2, 8505C, A2780, MCF-7, and A549) and possessed high inhibitory activity towards CAIX (Ki = 1.25 nM). The gene discussed is CA9; the disease is neoplasm.