Cl[C:2](=[CH2:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4].[Cl:9][C:10]1[CH:15]=[CH:14][C:13]([C:16]2O[C:19](=O)[S:18][N:17]=2)=[CH:12][CH:11]=1>ClC1C=CC=CC=1Cl>[Cl:9][C:10]1[CH:11]=[CH:12][C:13]([C:16]2[C:2]([C:3]([O:5][CH2:6][CH3:7])=[O:4])=[CH:19][S:18][N:17]=2)=[CH:14][CH:15]=1.[Cl:9][C:10]1[CH:15]=[CH:14][C:13]([C:16]2[CH:8]=[C:2]([C:3]([O:5][CH2:6][CH3:7])=[O:4])[S:18][N:17]=2)=[CH:12][CH:11]=1A solution of 40.4 g (0.30 mol) of ethyl 2-chloroacrylate and 2.14 g (0.010 mol) of 5-(p-chlorophenyl)-1,3,4-oxathiazole-2-one in 75 g of o-dichlorobenzene was held at reflux (165°-175°) for 55 minutes, at which time gas chromatography analysis indicated about 70% reaction. The reaction mixture was allowed to cool, and the supernatant was decanted from polymeric ester. Concentration of the supernatant under vacuum, chromatography of the residue on silicic acid, and crystallizations of the various materials thus obtained gave 0.30 g (16%) of ethyl 3-(p-chlorophenyl)-4-isothiazolecarboxylate, m.p. 69°-70°, and 0.31 g (17%) of ethyl 3-(p-chlorophenyl)-5-isothiazolecarboxylate, m.p. 87°-89°.
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