Synthesis and structure–activity relationship of a novel sulfone series of TNF-α converting enzyme inhibitors

Replacement of the amide functionality in IM491 (N-hydroxy-(5S,6S)-1-methyl-6-{[4-(2-methyl-4-quinolinylmethoxy)anilinyl]carbonyl}-5-piperidinecarboxamide) with a sulfonyl group led to a new series of α,β-cyclic and β,β-cyclic γ-sulfonyl hydroxamic acids, which were potent TNF-α converting enzyme (TACE) inhibitors. Among them, inhibitor 4b (N-hydroxy-(4S,5S)-1-methyl-5-{[4-(2-methyl-4-quinolinylmethoxy)phenyl]sulfonylmethyl}-4-pyrrolidinecarboxamide) exhibited IC50 values of <1 nM and 180 nM in porcine TACE (pTACE) and cell assays, respectively, with excellent selectivity over MMP−1, −2, −9 and −13 and was orally bioavailable with an F value of 46% in mice.