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Highly Potent and Orally Active CCR5 Antagonists as Anti-HIV-1 Agents:  Synthesis and Biological Activities of 1-Benzazocine Derivatives Containing a Sulfoxide Moiety

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journal contribution
posted on 23.03.2006, 00:00 by Masaki Seto, Katsuji Aikawa, Naoki Miyamoto, Yoshio Aramaki, Naoyuki Kanzaki, Katsunori Takashima, Yoji Kuze, Yuji Iizawa, Masanori Baba, Mitsuru Shiraishi
Chemical modification has been performed on an orally bioavailable and potent CCR5 antagonist, sulfoxide compound 4, mainly focusing on replacement of the [6,7]-fused 1-benzazepine nucleus. We designed, synthesized, and evaluated the biological activities of ring-expanded [6,8]-, [6,9]-, and [6,10]-fused compounds containing S-sulfoxide moieties, which led to the discovery of 1-benzazocine and 1-benzazonine compounds that exhibited potent inhibitory activities (equivalent to compound 4) in a binding assay. In addition, 1-benzazocine compounds possessing the S-sulfoxide moiety ((S)-(−)-5a,b,d,e) showed greater potency than compound 4 in a fusion assay. From further investigation in a multi-round infection assay, it was found that 1-isobutyl-1-benzazocine compound (S)-(−)-5b, containing the S-{[(1-propyl-1H-imidazol)-5-yl]methyl}sulfinyl group, showed the most potent anti-HIV-1 activity (IC90 = 0.81 nM, in MOLT4/CCR5 cells). Compound (S)-(−)-5b (TAK-652) also inhibited the replication of six macrophage-tropic (CCR5-using or R5) HIV-1 clinical isolates in peripheral blood mononuclear cells (PBMCs) (mean IC90 = 0.25 nM). It was also absorbed after oral administration in rats, dogs, and monkeys and was thus selected as a clinical candidate. The synthesis and biological activity of the 1-benzazocine compound (S)-(−)-5b and its related derivatives are described.