C(OC(=O)[C:5]1[CH:10]=[CH:9][CH:8]=[N:7][C:6]=1[CH:11]1[CH:16]=[CH:15][CH2:14][N:13](C(OCC)=O)[N:12]1[C:22]([O:24]CC)=O)C.OS(O)(=O)=O.C([O-])([O-])=O.[Na+].[Na+]>O>[NH:13]1[CH2:14][CH2:15][CH:16]=[C:11]2[C:6]3[N:7]=[CH:8][CH:9]=[CH:10][C:5]=3[C:22](=[O:24])[N:12]126.6 g of 2-(1,2-diethoxycarbonyl-1,2,3,6-tetrahydropyridazin-3-yl)nicotinic acid ethyl ester are mixed with 15 ml water and 60 ml of H2SO4 added with cooling. The reaction mixture is heated under nitrogen to 120° over 1 hr in a hot oil bath. The mixture is slowly poured into 125 g Na2CO3 and 250 g of ice and 125 ml of water. The alkaline mixture is filtered through celite and repeatedly extracted with ethylacetate (8×100 ml) and the extracts dried over MgSO4. After filtration the solvent is removed by evaporation under vacuum to yield the title compound which is recrystalized from CH3CN.
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