[CH2:1]([O:3][C:4](=[O:14])[C:5]1[C:10]([O:11][CH2:12][CH3:13])=[CH:9][CH:8]=[N:7][CH:6]=1)[CH3:2].[CH3:15][O:16][C:17]1[CH:18]=[CH:19][C:20]2[CH:23]=[C:22]([CH2:24][O:25][S:26]([C:29]3[CH:34]=[CH:33][C:32]([CH3:35])=[CH:31][CH:30]=3)(=[O:28])=[O:27])[C:21]=2[CH:36]=1>C(O)C>[S:26]([C:29]1[CH:34]=[CH:33][C:32]([CH3:35])=[CH:31][CH:30]=1)([O-:28])(=[O:27])=[O:25].[CH3:15][O:16][C:17]1[CH:18]=[CH:19][C:20]2[CH:23]=[C:22]([CH2:24][N+:7]3[CH:8]=[CH:9][C:10]([O:11][CH2:12][CH3:13])=[C:5]([C:4]([O:3][CH2:1][CH3:2])=[O:14])[CH:6]=3)[C:21]=2[CH:36]=119.52 g of 4-ethoxynicotinic acid ethyl ester are added to a solution of 31.84 g (0.1 mol) of p-toluenesulphonic acid (5-methoxybenzocyclobuten-1-yl)methyl ester in 150 ml of 95% ethanol and the whole is stirred for 3 days at room temperature. After distilling off the solvent under reduced pressure, 1-[(5-methoxy- benzocyclobuten-1-yl)methyl]-3-ethoxycarbonyl-4-ethoxypyridinium tosylate is obtained in the form of a light-yellow foam.
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