(−)-6-(7-Methoxy-2-(trifluoromethyl) pyrazolo [1, 5-a] pyridin-4-yl)-5-methyl-4, 5- dihydropyridazin-3 (2H)-one (KCA-1490) exhibits moderate dual PDE3/4-inhibitory activity and promises as a combined bronchodilatory/anti-inflammatory agent. N-alkylation of the pyridazinone ring markedly enhances potency against PDE4 but suppresses PDE3 inhibition. Addition of a 6-aryl-4, 5-dihydropyridazin-3 (2H)-one extension to the N-alkyl ...
[Chan, Louis K. M.; Poole, Darren L.; Shen, Di; Healy, Mark P.; Donohoe, Timothy J. Angewandte Chemie - International Edition, 2014 , vol. 53, # 3 p. 761 - 765 Angew. Chem., 2014 , vol. 126, # 3 p. 908]