Expanding chemical space of N-acyl sulfonamides for carbonic anhydrase inhibitor discovery

N-Acyl sulfonamides are widely recognized carboxylic acid isosteres that can fill the gap related to acidic compounds in chemical catalogs and bioactivity studies. This study presents the generation of synthetically tractable N-acyl sulfonamide chemical space based on the two-step parallel synthetic methodologies yielding structurally diverse compounds with high efficiency. Amide formation and S_NAr combined with primary sulfonamide acylation proved to be highly effective in generating structurally diverse N-acyl sulfonamides with typically good synthesis success rates (up to 83 %) and average yields (up to 57 %). The approach demonstrated reliability across different substrates, supporting the efficient construction of a 526-member compound library (out of 3,258,356 possible combinations) with minor synthetic limitations. Biological evaluations of the synthesized library identified promising inhibitors of human carbonic anhydrase isoforms hCA-IX and hCA-II. Differential scanning fluorimetry screening and enzymatic assays revealed potent and selective compounds, with some derivatives exhibiting low micromolar IC₅₀ values (i.e., N-((2-((2-(3-(dimethylamino)-1,2,4-oxadiazol-5-yl)ethyl)amino)thiazol-5-yl)sulfonyl)-2-(pyrrolidin-1-yl)isonicotinamide trifluoroacetate; hCA-IX IC₅₀ = 1.2 μM; hCA-II IC₅₀ = 6.7 μM) and selectivity toward hCA-IX (i.e., 3-chloro-N-((1-(5-(hydroxymethyl)-1,3,4-thiadiazol-2-yl)pyrrolidin-3-yl)sulfonyl)benzamide; hCA-IX IC₅₀ = 11.5 μM; hCA-II IC₅₀ = 192 μM). Several examples demonstrated moderate selectivity towards hCA-II, e.g. N-((5-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-4,5,6,7-tetrahydrothieno[3,2-c]pyridin-2-yl)sulfonyl)furan-2-carboxamide (hCA-IX IC₅₀ = 32.8 μM; hCA-II IC₅₀ = 4.4 μM) and N-((2-methyl-4-((1-(phenoxymethyl)cyclopropyl)carbamoyl)phenyl)sulfonyl)-1-(trifluoromethyl)-1H-pyrazole-4-carboxamide (hCA-IX IC₅₀ = 46.3 μM; hCA-II IC₅₀ = 5.5 μM). Molecular docking and molecular dynamics simulations provided further insights into binding interactions, confirming the stability of ligand-protein complexes. Thus, this work highlights the synthetic efficiency and pharmacological relevance of N-acyl sulfonamides, expanding the accessible chemical space for drug discovery.