Lead identification of benzimidazolone and azabenzimidazolone arylsulfonamides as CC-chemokine receptor 4 (CCR4) antagonists

A knowledge-based library of 2,3-dichlorophenylsulfonyl derivatives of commercially available aryl amines was synthesised and screened as human CCR4 antagonists, in order to identify a suitable hit for the start of a lead-optimisation programme. Hits were required to be more potent than an existing indazole series, have better physicochemical properties (c log P <3.5, chrom log D_7.4 <5.3 and CLND solubility >116 μg/mL), and be stable to acid and light. The benzimidazol-2-one core was identified as a hit suitable for further investigation. Substitution at N1 with small alkyl groups was tolerated; however, these analogues were inactive in the whole blood assay (pA₂ <5). Azabenzimidazolone analogues were all found to be active, with compound 38 exhibiting whole blood activity of 6.1, low molecular weight (389) and chrom log D_7.4 (2.4), high LE (0.43), and solubility (152 μg/mL). In addition, 38 had human serum albumin binding of around 93% and met all the criteria for progression to lead optimisation.