title: Palladium-catalyzed cross-coupling reactions for the synthesis of 6, 8-disubstituted 1,7-naphthyridines: a novel class of potent and selective phosphodiesterase type 4D inhibitors.
abstract: Recently, four subtypes of the human phosphodiesterase type 4 (PDE4A-D) enzyme have been described. So far, only very few PDE4 subtype-selective inhibitors are known. Herein, we describe the synthesis of 6,8-disubstituted 1,7-naphthyridines and their characterization as potent and selective inhibitors of PDE4D which suppress the oxidative burst in human eosinophils with IC(50) values as low as 0.7 nM. SAR development and the extended use of palladium-catalyzed cross-coupling reactions led to compound 11 which inhibited human PDE4D with an IC(50) value of 1 nM. Thus, compound 11 was 55, 175, and 1000 times more potent in inhibiting PDE4D over PDE4B, PDE4A, and PDE4C. In a Brown Norway rat model of allergic asthma, compound 11 when given by the oral route (1 mg/kg) reduced by more than 50% the influx of eosinophils, T-cells, and neutrophils into bronchoalveolar lavage fluid (BALF) samples obtained from antigen-challenged animals. Thus, PDE4D-selective inhibitors of the 1,7-naphthyridine class have the potential as an oral therapy for treating asthma.
authors.affiliation: Novartis Pharma AG, Research, CH-4002 Basel, Switzerland. rene.hersperger@pharma.novartis.com
authors.forename: R
authors.initials: R
authors.lastname: Hersperger
authors.forename: K
authors.initials: K
authors.lastname: Bray-French
authors.forename: L
authors.initials: L
authors.lastname: Mazzoni
authors.forename: T
authors.initials: T
authors.lastname: Müller
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000284:Administration, Oral; D000818:Animals; D018927:Anti-Asthmatic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001249:Asthma / Q000188:drug therapy / Q000473:pathology; D001565:Benzoates / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002384:Catalysis; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D004804:Eosinophils / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009287:Naphthyridines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D010165:Palladium; D051381:Rats; D016897:Respiratory Burst / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: C405045:4-(8-(3-nitrophenyl)-(1,7)naphthyridin-6-yl)benzoic acid; D018927:Anti-Asthmatic Agents; D001565:Benzoates; D004791:Enzyme Inhibitors; D009287:Naphthyridines; D010165:Palladium; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; C517355:PDE4A protein, human; C517360:PDE4B protein, human; C517361:PDE4C protein, human; C517376:PDE4D protein, human