The pyridine ring of 2-phenyl-2-(2-pyridyl) thioacetamide (Ia), the lead compound for the present study, was replaced by a pyridazine ring in the hope of obtaining more potent and less toxic drugs with long-lasting action, and a series of 2-phenyl-2-(3-pyridazinyl) thioacetamide derivatives (II) was synthesized from halopyridazines (III) and phenyl-acetonitriles via the key intermediates, 2-phenyl-2-(3-pyridazinyl) acetonitrile derivatives (IV). The chemical structure of II appears to be in equilibrium between the pyridazine form and the pyridazinone-methide form on the basis of nuclear magnetic resonance (NMR) and ultraviolet (UV) spectral data. The antisecretory activity and acute toxicity of II were investigated and the structure-activity relationships are discussed. Among the compounds tested, 2-Phenyl-2-(3-pyridazinyl) thioacetamide (IIa) and 2-(6-methyl-3-pyridazinyl)-2-phenylthioacetamide (IIb) possessed long-lasting, potent activity when administered to rats at 20 mg/kg. The acute toxicities of IIa and IIb were about half to one-third of that of Ia in mice.
Novel thioamide derivatives containing a pyridazine group
申请人:Morishita Pharmaceutical Co., Ltd.
公开号:US04242512A1
公开(公告)日:1980-12-30
Novel pyridazine-containing thioamide derivatives of the formula ##STR1## wherein R.sub.1 is ##STR2## wherein A is hydrogen, methyl, phenyl or mercapto, and B is hydrogen or phenyl; R.sub.2 is hydrogen or methyl; R.sub.3 is hydrogen, methyl or phenyl; R.sub.4 is hydrogen or methyl; and n is zero or 1. The derivatives have outstanding gastric antisecretory activity.
This paper describes a modified method of preparation of a number of α-aryl-α-(pyridazin-3-yl)-acetonitriles via the C-arylation reaction of the corresponding carbanionsof phenylacetonitriles using 3-chloropyridazine derivatives. KOH and DMSO were used inthe deprotonation process, which made the reaction very simple and safe to perform.Nitriles were obtained in the hydrolysis reaction to the corresponding α-aryl-α-(pyridazin-3-yl)-acetamide derivatives, which were next subjected to cyclization to afford the finalproducts. A number of new derivatives of 7H,8H-pyrimido[1,6-b]pyridazin-6,8-dione weresynthesized in the cyclocondensation reaction of respective α-aryl-α-(pyridazin-3-yl)-acetamides with diethyl carbonate in the presence of EtONa. The structure andcomposition of the new compounds were confirmed by IR, 1H- and 13C- NMR analysesand by elemental C, H and N analysis.