Phosphodiesterase inhibitors. Part 4: Design, synthesis and structure-activity relationships of dual PDE3/4-inhibitory fused bicyclic heteroaromatic-4,4-dimethylpyrazolones

Koji Ochiai, Satoshi Takita, Akihiko Kojima, Tomohiko Eiraku, Naoki Ando, Kazuhiko Iwase, Tetsuya Kishi, Akira Ohinata, Yuichi Yageta, Tokutaro Yasue, David R. Adams, Yasushi Kohno

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21 Citations (Scopus)


(-)-6-(7-Methoxy-2-trifluoromethylpyrazolo[1,5-a]pyridin-4-yl)-5-methyl-4,5-dihydro-3-(2H)-pyridazinone (KCA-1490) is a dual PDE3/4 inhibitor that exhibits potent combined bronchodilatory and anti-inflammatory activity. Here we show that a 4,4-dimethylpyrazolone subunit serves as an effective surrogate for the 5-methyl-4,5-dihydropyridazin-3(2H)-one ring of KCA-1490 whilst lacking a stereogenic centre. The 2- and 7-substituents in the pyrazolo[1,5-a] pyridine subunit markedly influence the PDE-inhibitory profile and can be adjusted to afford either potent PDE4-selective inhibitors or dual PDE3/4 inhibitors. A survey of bicyclic heteroaromatic replacements for the pyrazolo[1,5-a] pyridine allowed further refinement of the inhibitory profile and identified 3-(8-methoxy-2-(trifluoromethyl) imidazo [1,2-a]pyridin-5-yl)-4,4-dimethyl-1H-pyrazol-5(4H)-one as an orally active, achiral KCA-1490 analog with well-balanced dual PDE3/4-inhibitory activity. (C) 2012 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)5833-5838
Number of pages6
JournalBioorganic and Medicinal Chemistry Letters
Issue number18
Publication statusPublished - 15 Sep 2012

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